Shafter City Council
October 20, 2026

20-23
“Finding Hidden Mold: Case Studies in IAQ Investigations”, AIHA Northern California Professionals Symposium; Oakland, CA, May 8, 2002.
“Assessing and Mitigating Fungal Contamination in Buildings”, Cal/OSHA Training; Oakland, CA, February 14, 2003 and West Covina, CA, February 20-21, 2003. “Use of External Containments During Fungal Mitigation”, Healthy Indoor Environments, Anaheim, CA, April 3, 2003 and ACGIH Mold Remediation Symposium (Invited Speaker), Orlando, FL, November 3-5, 2003.

Building Operator Certification (BOC), 106-IAQ Training Workshops, Northwest Energy Efficiency Council; Stockton, CA, December 3, 2003; San Francisco, CA, December 9, 2003; Irvine, CA, January 13, 2004; San Diego, January 14, 2004; Irwindale, CA, January 27, 2004; Downey, CA, January 28, 2004; Santa Monica, CA, March 16, 2004; Ontario, CA, March 17, 2004; Ontario, CA, November 9, 2004, San Diego, CA, November 10, 2004; San Francisco, CA, November 17, 2004; San Jose, CA, November 18, 2004; Sacramento, CA, March 15, 2005.
“HVAC Systems Maintenance”, Cal/OSHA Training, Oakland and West Covina, CA, March 11, 2003.
“Mold Remediation: The National QUEST for Uniformity Symposium”, Invited Speaker, Orlando, Florida, November 3-5, 2003.
“Mold and Moisture Control”, Indoor Air Quality workshop for The Collaborative for High Performance Schools (CHPS), San Francisco, December 11, 2003. “Advanced Perspectives In Mold Prevention & Control Symposium”, Invited Speaker, Las Vegas, Nevada, November 7-9, 2004.
“Building Sciences: Understanding and Controlling Moisture in Buildings”, American Industrial Hygiene Association, San Francisco, CA, February 14-16, 2005. “Indoor Air Quality Diagnostics and Healthy Building Design”, University of California Berkeley, Berkeley, CA, March 2, 2005.
“Managing IAQ in Buildings and the USGBC Certification Program”, BOMA Environmental Committee, San Francisco, CA, June 1, 2006. “Improving IAQ = Reduced Tenant Complaints”, Northern California Facilities Exposition, Santa Clara, CA, September 27, 2007.
“Defining Safe Building Air”, Criteria for Safe Air and Water in Buildings, ASHRAE Winter Meeting, Chicago, IL, January 27, 2008.
“USGBC LEED and Indoor Air Quality : Leading or Lagging ?”, Bay Area LEED Users Group (BAyLUG), San Francisco, CA, June 5, 2008

21-23
“Window Usage, Ventilation, and Formaldehyde Concentrations in New California Homes”, Indoor Air 2008, Copenhagen, Denmark.
“ETS in Multi-Family Housing: Exposures, Controls, and Legalities”, Indoor Air 2008, Copenhagen, Denmark.
“Update on USGBC LEED and Air Filtration”, Invited Speaker, NAFA 2008 Convention, San Francisco, CA, September 19, 2008.
“Indoor Air Quality Requirements of Green Buildings”, Northern California Facilities Exposition, Santa Clara, CA, September 25, 2008.
“Ventilation and Indoor air Quality in New California Homes”, National Center of Healthy Housing, October 20, 2008.
“Indoor Air Quality in New Homes”, California Energy and Air Quality Conference, October 29, 2008.
“Mechanical Outdoor air Ventilation Systems and IAQ in New Homes”, ACI Home Performance Conference, Kansas City, MO, April 29, 2009. “Student Performance and Absenteeism Related to IAQ”, Balancing IAQ and Energy Conservation/Efficiency Objectives in Schools ASHRAE Summer Meeting, Louisville, KY, June 21, 2009
“Ventilation and IAQ in New Homes with and without Mechanical Outdoor Air Systems”, Healthy Buildings 2009, Syracuse, CA, September 14, 2009. “Ten Ways to Improve Your Air Quality”, Northern California Facilities Exposition, Santa Clara, CA, September 30, 2009.
“New Developments in Ventilation and Indoor Air Quality in Residential Buildings”, Westcon meeting, Alameda, CA, March 17, 2010.
“Intermittent Residential Mechanical Outdoor Air Ventilation Systems and IAQ”, ASHRAE SSPC 62.2 Meeting, Austin, TX, April 19, 2010.
“ASHRAE 62.2 Intermittent Residential Ventilation: What’s It Good For, Intermittently Poor IAQ”, IAQVEC 2010, Syracuse, CA, April 21, 2010.
“Measured IAQ in Homes”, ACI Home Performance Conference, Austin, TX, April 21, 2010.
“Respiration: IEQ and Ventilation”, AIHCE 2010, How IH Can LEED in Green Buildings, Denver, CO, May 23, 2010.

22-23
“IAQ Considerations for Net Zero Energy Buildings (NZEB)”, Northern California Facilities Exposition, Santa Clara, CA, September 22, 2010. “Energy Conservation and Health in Buildings”, Berkeley High School Green Career Week, Berkeley, CA, April 12, 2011.
“What Pollutants are Really There ?”, ACI Home Performance Conference, San Francisco, CA, March 30, 2011.
“Energy Conservation and Health in Residences Workshop”, Indoor Air 2011, Austin, TX, June 6, 2011.
“Assessing IAQ and Improving Health in Residences”, US EPA Weatherization Plus Health, September 7, 2011.
“Ventilation: What a Long Strange Trip It’s Been”, Westcon, May 21, 2014. “Chemical Emissions from E-Cigarettes: Direct and Indirect Passive Exposures”, Indoor Air 2014, Hong Kong, July, 2014.
“Infectious Disease Aerosol Exposures With and Without Surge Control Ventilation System Modifications”, Indoor Air 2014, Hong Kong, July, 2014. “Chemical Emissions from E-Cigarettes”, IMF Health and Welfare Fair, Washington, DC, February 18, 2015.
“Chemical Emissions and Health Hazards Associated with E-Cigarettes”, Roswell Park Cancer Institute, Buffalo, NY, August 15, 2014.
“Formaldehyde Indoor Concentrations, Material Emission Rates, and the CARB ATCM”, Harris Martin’s Lumber Liquidators Flooring Litigation Conference, WQ Minneapolis Hotel, May 27, 2015.
“Chemical Emissions from E-Cigarettes: Direct and Indirect Passive Exposure”, FDA Public Workshop: Electronic Cigarettes and the Public Health, Hyattsville, MD June 2, 2015.
“Creating Healthy Homes, Schools, and Workplaces”, Chautauqua Institution, Athenaeum Hotel, August 24, 2015.
“Diagnosing IAQ Problems and Designing Healthy Buildings”, University of California Berkeley, Berkeley, CA, October 6, 2015.
“Diagnosing Ventilation and IAQ Problems in Commercial Buildings”, BEST Center Annual Institute, Lawrence Berkeley National Laboratory, January 6, 2016. “A Review of Studies of Ventilation and Indoor Air Quality in New Homes and Impacts

23-23
of Environmental Factors on Formaldehyde Emission Rates From Composite Wood Products”, AIHce2016, May, 21-26, 2016.
“Admissibility of Scientific Testimony”, Science in the Court, Proposition 65 Clearinghouse Annual Conference, Oakland, CA, September 15, 2016. “Indoor Air Quality and Ventilation”, ASHRAE Redwood Empire, Napa, CA, December 1, 2016.
“Energy Conservation and Health in Buildings”, Berkeley High School Green Career Week, Berkeley, CA, March 8, 2017.
“What Does ‘Use With Adequate Ventilation’ Mean ?”, Indoor Air 2018, Philadelphia, PA, July, 2018.
“Ventilation, Air Filtration, and COVID-19, Avoiding the Snake Oil Salesman”, IAQ Radio, January 29, 2021.
“How to Prevent Snake Oil Sales from the IAQ Industry”. Healthy Indoors Live Show, April 15, 2021.
“Ventilation, Air Filtration, and COVID-19: Avoiding the Snake Oil Salesman” OCFMA Presentation, June 3, 2021.
“Ventilation, Air Filtration, and COVID-19, Avoiding the Snake Oil Salesman”, Ontario College Facilities Management Association, June 23, 2021. “Air Quality Expert Warns of COVID-19 Snake Oil Salesmen”. NBC Bay Area, August 4, 2021.
“Managing Wildfire Smoke Indoors During COVID 19”, ASHRAE Golden Gate Chapter, San Francisco, CA, February 17, 2022.
“Chemical Emissions from Spray Polyurethane Foam (SPF) Insulation in Residences, Indoor Air 2022, Kuopio, Finland, June, 2022.
“How good is your ventilation? Indoor Air Quality and the passenger experience within Airports”. 2022 Greenbuild International Conference & Expo, November 1-3, 2022. “Assessing and Mitigating Fungal Contamination in Buildings”. Cal/OSHA Training.

Oakland, CA (February 14, 2003) West Covina, CA (February 20 and 21, 2003). “Mold Contamination in Buildings”, Tenant Law Group – Lunch and Learn, April, 19, 2023.
“Ventilation / Filtration and Tenants” Regional Asthma Management and Prevention, June 29, 2023 Webinar.

EXHIBIT C

388 17th Street, Suite 230, Oakland, CA 94612 | (510) 420-8686 | www.baseline-env.com October 2, 2026
26251-00
Carly Steele
Lozeau Drury LLP
1939 Harrison St., Suite 150
Oakland, CA 94612
Subject: Review of Air Quality and Greenhouse Gas Emissions Impacts Analyzed for the Mission Lakes Specific Plan
Dear Ms. Steele:

Baseline Environmental Consulting (Baseline) has reviewed the 2005 General Plan Update Program Environmental Impact Report (2005 PEIR)1 for the City of Shafter that included adoption of the proposed Mission Lakes Specific Plan (Plan). The proposed Plan includes development of 5,334 residential dwelling units on 1,347 acres, 68 acres of public parks, 129 acres of commercial development, one 25-acre middle school, and one 15-acre elementary school. The purpose of our review was to determine whether subsequent CEQA environmental review is required for air quality or greenhouse gas (GHG) emissions prior to development under the proposed Plan.

The air quality analysis in the 2005 PEIR found that the increase of criteria air pollutants resulting from implementation of the proposed Plan would result in the following impacts:
 Short-Term Construction-Related Air Pollutant Emissions. Impacts of the proposed project will be less than significant with the implementation of the proposed General Plan policy and SJVAPCD Regulation VIII.
 Long-Term Construction-Related Air Pollutant Emissions. Implementation of the policies provided in the proposed General Plan will reduce the long-term increase in air pollutants due to vehicle emissions; however, emissions would remain significant and unavoidable.

The analysis of air quality impacts in the 2005 PEIR was based on the San Joaquin Valley Air Pollution Control District’s (SJVAPCD) Guidance for Assessing and Mitigating Air Quality Impacts that was published in January 2002, which has since been superseded by the SJVAPCD’s current 1 LSA Associates, Inc., 2005. Draft Program Environmental Impact Report, City of Shafter General Plan Update, SCH 2004101029, Kern County, California. April.

October 2, 2026

guidance that was published in March 2015.2 The current guidance incorporates updated emissions modeling software, modernized thresholds, and rules regarding GHG emissions and localized health risk assessments that could not have been known with the exercise of reasonable diligence at the time the 2005 PEIR was certified. According to CEQA Guidelines Section 15162(a)(3), this would be considered new information of substantial importance subject to subsequent CEQA environmental review if any of the following criteria apply:

A. The project will have one or more significant effects not discussed in the previous EIR or negative declaration;
B. Significant effects previously examined will be substantially more severe than shown in the previous EIR;
C. Mitigation measures or alternatives previously found not to be feasible would in fact be feasible, and would substantially reduce one or more significant effects of the project, but the project proponents decline to adopt the mitigation measure or alternative; or D. Mitigation measures or alternatives which are considerably different from those analyzed in the previous EIR would substantially reduce one or more significant effects on the environment, but the project proponents decline to adopt the mitigation measure or alternative.

As discussed below, the SJVAPCD’s updates to modeling software, modernized thresholds, and rules regarding GHG emissions and localized health risk assessments are considered new information of substantial importance under CEQA Guidelines Sections 15162(a)(3)(A) and 15162(a)(3)(D).

CEQA Guidelines Section 15162(a)(3)(A)
New Significant Criteria Air Pollutant Emissions
The 2005 PEIR estimated long-term criteria air pollutant emissions from anticipated City development, including development under the proposed Plan, using the 2002 URBEMIS model. The URBEMIS model is an obsolete model that has been superseded by the 2022 California Emissions Estimator Model (CalEEMod). The URBEMIS model only captured direct emissions (tailpipes, construction equipment, hearths), whereas CalEEMod also quantifies indirect emissions associated with consumer products, energy consumption, water delivery/treatment, and solid waste disposal while utilizing sub-regional default data customized by individual local Air Quality Management Districts. The URBEMIS model also did not have the ability to calculate GHG emissions, whereas CalEEMod does quantity both direct and indirect GHG emissions.
2 San Joaquin Valley Air Pollution Control District, 2015. Guidance for Assessing and Mitigating Air Quality Impacts.

October 2, 2026

The 2005 PEIR did not estimate short-term criteria air pollutant emissions from construction, indirect emissions from operation, nor overlapping emissions from construction and operation that would be anticipated under the proposed Plan. Based on the updated emissions modeling software and SJVAPCD’s current thresholds, the extent of significant and unavoidable air quality impacts related to criteria air pollutant emissions have not been disclosed. As discussed further below, there are new mitigation measures readily available that would substantially reduce the severity of significant air quality impacts associated with implementation of the proposed Plan.

New Significant Localized Health Risks
The 2005 PEIR did not evaluate local health risks to nearby sensitive receptors exposed to toxic air contaminants during construction and operation of the proposed Plan. Construction activities would generate diesel particulate matter (DPM) emissions from the exhaust of offroad diesel equipment that could pose a health risk to nearby sensitive receptors. The California Air Resources Board has identified DPM as a toxic air contaminant based on its potential to cause cancer and other adverse health effects.3
Adverse health effects associated with
particulate matter can vary based on factors such as particle size, source, and chemical composition. DPM is typically composed of carbon particles and a variety of organic compounds including more than 40 known cancer-causing organic substances. Additionally, over 90 percent of DPM is less than 1 micron in diameter and can deposit in the deepest regions of the lungs where the lungs are most susceptible to injury.

In 2015, the Office of Environmental Health Hazard Assessment (OEHHA) published guidance for preparing health risk assessments.4 According to OEHHA, there is valid scientific concern regarding the health effects on children exposed to airborne carcinogens such as DPM from short-term construction activities lasting more than two months. This is because infants and children are generally more susceptible to health effects from exposure to carcinogens than adults. In addition, when accounting for the higher breathing rate per body mass and higher fraction of time at home for a child versus an adult, the estimated cancer risk for a child can be up to 48 times higher than an adult exposed to the same concentration of DPM. Similar health risks concerns also apply to operational sources of toxic air contaminants that could be introduced under the Plan, such as DPM emissions from the exhaust of diesel emergency generators or warehouse trucks, or volatile organic gases from new gas stations.

Based on the current research and guidance developed by OEHHA for localized health risk assessments, potential significant and unavoidable air quality impacts related to toxic air contaminant emissions have not been disclosed. As discussed further below, there are new 3 California Air Resources Board, 1998. Initial Statement of Reasons for Rulemaking; Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant, June.
4 Office of Environmental Health Hazard Assessment. 2015. Air Toxics Hot Spots Program Guidance Manual for Preparation of Health Risk Assessments. February.

October 2, 2026

mitigation measures readily available that would substantially reduce the severity of significant air quality impacts associated with implementation of the proposed Plan.

New Significant Greenhouse Gas Impacts
The 2005 PEIR did not evaluate or estimate GHG emissions associated with implementation of the proposed Plan. Based on current statewide GHG reduction goals, research, modeling software, and regulatory guidance, implementation of the Plan could have a significant and unavoidable impact related to GHG emissions. As discussed further below, there are new mitigation measures readily available that would substantially reduce the severity of significant GHG emissions impacts associated with implementation of the proposed Plan.

CEQA Guidelines Section 15162(a)(3)(D)
As discussed below, there are additional mitigation measures that could be evaluated and implemented under the Plan that were not considered and/or were not readily available when the 2005 PEIR was certified.

When the 2005 PEIR was prepared, off-road diesel equipment with Tier 3, Tier 4 Interim, and Tier 4 Final Interim engines were not readily available. The cleanest diesel engines available for off-road equipment in 2005 were Tier 2 engines. For off-road equipment with diesel engines greater than 75 horsepower, Tier 4 Final engines reduce nitrogen oxide (NOx) and coarse particulate matter (PM10) emissions by over 90% compared to Tier 2 engines. New mitigation measures requiring the use of Tier 4 final engines would significantly reduce the severity of criteria air pollutant and DPM emissions associated with development under the proposed Plan.

When the 2005 PEIR was prepared, the fleetwide average running exhaust emission factor for NOx from Class 8 on-road heavy-duty diesel tractor trucks in Kern County was approximately

9.15 grams per mile. According to the California Air Resources Board’s EMFAC2025 database,5 the running exhaust emission factor for NOx from Class 8 diesel tractor trucks with model year 2014 or later engines is approximately 0.71 grams per mile, which is approximately 92% lower than the 2005 fleetwide average emission factor. New mitigation measures requiring the use of 2014 or later engines for heavy-duty diesel tractor trucks during construction (e.g., haul trucks) and operation (e.g., warehouse trucks) would significantly reduce the severity of criteria air pollutant and DPM emissions associated with development under the proposed Plan.

When the 2005 PEIR was prepared, flat and non-flat paint coatings for residential and nonresidential buildings were limited to a maximum volatile organic compound (VOC) content of 250 grams per liter and 380 grams per liter, respectively, under the SJVAPCD’s original Rule 4601. Architectural coatings are a major source of reactive organic gas (ROG) emissions, a 5 California Air Resources Board, 2026. EMission FACtor (EMFAC) 2025 version2.1.1. Accessed on October 2. https://emfac.arb.ca.gov/.

October 2, 2026

precursor for the formation of ground-level ozone. The SJVAPCD has updated Rule 4601 to limit the VOC content for these paints to 50 grams per liter. However, in recent years, paint manufacturers have developed super-compliant VOC paints with a maximum VOC content of 10 grams per liter for widespread use in California, which were not available when the 2005 PEIR was certified. Super-compliant VOC paints would reduce ROG emissions by at least 96% compared to the 2005 VOC content in paints and by approximately 80% compared to the current regulatory requirements. New mitigation measures requiring the use of supercompliant VOC paints would significantly reduce the severity of criteria air pollutant emissions associated with development under the proposed Plan.

When the 2005 PEIR was prepared, California had not adopted strategies to achieve the following long-term climate action goals:
 Assembly Bill (AB) 32: Reduce GHG emissions to 1990 levels by 2020.  Senate Bill (SB) 32: Reduce GHG emissions to 40 percent below 1990 levels by 2030.  AB 1279: Achieve carbon neutrality as soon as possible, but no later than 2045 and maintain net negative GHG emissions thereafter; and reduce GHG emissions to 85 percent below 1990 levels by 2045.

The 2005 PEIR did not evaluate GHG emissions and how development under the proposed Plan would achieve statewide climate goals. The California Air Resources Board’s current 2022 Scoping Plan for Achieving Carbon Neutrality (2022 Scoping Plan) provides guidance for residential and commercial projects to demonstrate alignment with the State’s long-term climate goals, with a focus on the following three priority areas:
 Transportation electrification
 Vehicle miles travelled (VMT) reduction
 Building decarbonization
New mitigation measures are readily available that would align future development under the Plan with the 2022 Scoping Plan, such as providing electric vehicle (EV) charging infrastructure that, at minimum, meets the most ambitious voluntary standard in the California Green Building Standards Code and requiring the use of all-electric appliances without any natural gas connections. New mitigation measures that demonstrate consistency with the priority areas of the 2022 Scoping Plan would significantly reduce the severity of GHG emissions associated with development under the proposed Plan.

Conclusion
According to CEQA Guidelines Section 15162(a)(3)(A), additional CEQA review is required if implementation of the proposed Plan will result in one or more significant effects not discussed in the previous EIR. As described above, development of the Plan may result in significant impacts related to criteria air pollutants, localized health risks, and GHG emissions that were

October 2, 2026

not evaluated in the 2005 PEIR because current emissions modeling software, scientific research, regulatory guidance, and rules regarding air pollutant emissions and localized health risks were not available. Therefore, additional CEQA review of the Plan is warranted to evaluate, mitigate, and disclose the severity of potential air quality and GHG emissions impacts to the public.

According to CEQA Guidelines Section 15162(a)(3)(D), additional CEQA review is also required if mitigation measures which are considerably different from those analyzed in the previous EIR would substantially reduce one or more significant effects on the environment. As described above, there are readily available mitigation measures that would substantially reduce emissions of criteria air pollutants, DPM, and GHGs related to development under the proposed Plan. Therefore, additional CEQA review of the Plan is warranted to evaluate, mitigate, and disclose the severity of potential air quality and GHG emissions impacts to the public.

Sincerely,

Patrick Sutton
Principal Environmental Engineer

ATTACHMENT A
Staff Resume

Patrick Sutton, P.E.

Principal Environmental Engineer
Areas of Expertise
Air Quality, GHGs, Noise, Hazardous
Materials, Geology, and Hydrology
Education
M.S., Civil and Environmental
Engineering, University of
California – Davis
B.S., Environmental Science,
Dickinson College
Registration
Professional Engineer No. 13609 (RI)
Years of Experience
22 Years
Patrick Sutton is an environmental engineer who specializes in the assessment of hazardous materials released into the environment.

Mr. Sutton prepares technical reports in support of environmental review, such as Phase I/II Environmental Site Investigations, Air Quality Reports, and Health Risk Assessments. He has prepared numerous CEQA/NEPA evaluations for air quality, GHGs, noise, energy, geology, hazardous materials, and water quality related to residential, commercial, and industrial projects, as well as large infrastructure developments. His proficiency in a wide range of modeling software (AERMOD, CalEEMod, RCEM, CT-EMFAC) as well as relational databases, GIS, and graphics design allows him to thoroughly and efficiently assess and mitigate environmental concerns.

For mixed-use development projects, Mr. Sutton has prepared health risk assessments for sensitive receptors exposed to toxic air contaminants based on air dispersion modeling. For large transportation improvement projects, Mr. Sutton has prepared air quality and hazardous materials technical reports in accordance with Caltrans requirements. The air quality assessments include the evaluation of criteria air pollutants, mobile source air toxics, and GHG emissions to support environmental review of the project under CEQA/NEPA and to determine conformity with the State
Implementation Plan. The hazardous materials investigations include sampling and statistically analysis of aerially-deposited lead adjacent to highway corridors. Mr. Sutton is also an active member of ASTM International and is the author of the Standard Practice for Low-Flow Purging and Sampling Used for Groundwater Monitoring.

Project Experience
Alameda CTC I-80/Ashby Avenue Interchange Improvements. Prepared Phase I/II ESAs to evaluate contaminants of potential concern in soil and groundwater. Prepared Air Quality Report to determine the project’s conformity to federal air quality regulations and support CEQA/NEPA environmental review.

Oakland Downtown Specific Plan EIR. Prepared a program- and project-level Air Quality and GHG Emissions analysis. Developed a mitigation measure with performance standards to ensure GHG emissions from future projects comply with the Citywide 2030 GHG reduction target.

Alameda CTC I-680 Express Lanes from SR 84 to Alcosta Boulevard Project. Prepared Initial Site Assessment and Preliminary Site Investigation to evaluate contaminants of potential concern in soil and groundwater. Prepared Air Quality Report to determine the project’s conformity to federal air quality regulations and to support environmental review of the project under CEQA and NEPA.

Altamont Corridor Expressway (ACE/Forward) Project EIR/EIS. Prepared a program- and project-level Hazardous Materials analysis for over 120 miles of railroad corridor from San Jose to Merced. Hazardous materials concerns, such as release sites, petroleum pipelines, agricultural pesticides, and nearby school sites were evaluated in GIS.

BART Silicon Valley Extension Project. Prepared Initial Site Assessment and Hazardous Materials EIS/EIR section for extending 6 miles of proposed BART service through the Cities of San Jose and Santa Clara.

EXHIBIT D

Lawrence Berkeley National Laboratory
LBL Publications
Title
Indoor air quality in California homes with code‐required mechanical ventilation Permalink
https://escholarship.org/uc/item/5284d4tk
Journal
Indoor Air, 30(5)
ISSN
0905-6947
Authors
Singer, Brett C
Chan, Wanyu R
Kim, Yang‐Seon
et al.

Publication Date
2020-05-12
DOI

10.1111/ina.12676
Peer reviewed
eScholarship.org Powered by the California Digital Library University of California

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 1
1 Indoor Air Quality in California Homes with Code-Required Mechanical Ventilation Brett C. Singer1, Wanyu R. Chan1, Yang-Seon Kim1,2, Francis J. Offermann 3 , Iain S. Walker1 2
1 3 Residential Buildings Systems Group and Indoor Environment Group, Lawrence Berkeley 4 National Laboratory, Berkeley, California, USA
2 5 Department of Mechanical Engineering, Wichita State University, Wichita, Kansas, USA 3 6 Indoor Environmental Engineering, San Francisco California, USA 7 Acknowledgements
8 This work was supported by the California Energy Commission through Contract PIR-14-007 9 and the U.S. Department of Energy Building America Program via Contract DE-AC02- 10 05CH11231. The Southern California Gas Company (SoCalGas) provided direct funding to the 11 Gas Technology Institute (GTI) and staff resources to support an online survey and field data 12 collection. The Pacific Gas & Electric Company (PG&E) funded Misti Bruceri & Associates 13 (MBA) to provide a field technician. SoCalGas and PG&E deployed Gas Service Technicians to 14 conduct appliance safety inspections in study homes. Data collection in homes was conducted by 15 Luke Bingham, Erin Case, and Shawn Scott of GTI; Guy Lawrence of MBA; Eric Barba, Mary 16 Nones, Ara Arouthinounian, and Ricardo Torres of SoCalGas; and Woody Delp of LBNL. Rick 17 Chitwood assisted with data collection and guidance on measuring airflow in supply ventilation 18 systems. Max Sherman (retired from LBNL) helped develop the project and served as the initial 19 Principal Investigator. Genese Scott of SoCalGas helped with online survey recruitment. Marion 20 Russell of LBNL led the chemical analysis of air samples. Kelly Perce transferred survey and 21 activity log data from paper to the survey database. The CalCERTS and CHEERS organizations 22 provided Title 24 compliance records for many study homes. Neil Leslie, Larry Brand, and Rob 23 Kamisky of GTI provided management support.
24 25

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 2
1 Abstract
2 Data were collected in 70 detached houses built in 2011-2017 in compliance with the mechanical 3 ventilation requirements of California’s building energy efficiency standards. Each home was 4 monitored for a one-week period with windows closed and the central mechanical ventilation 5 system operating. Pollutant measurements included time-resolved fine particulate matter (PM2.5) 6 indoors and outdoors and formaldehyde and carbon dioxide (CO2) indoors. Time-integrated 7 measurements were made for formaldehyde, NO2 and nitrogen oxides (NOX) indoors and 8 outdoors. Operation of the cooktop, range hood and other exhaust fans was continuously 9 recorded during the monitoring period. One-time diagnostic measurements included mechanical 10 airflows and envelope and duct system air leakage. All homes met or were very close to meeting 11 the ventilation requirements. On average the dwelling unit ventilation fan moved 50% more 12 airflow than the minimum requirement. Pollutant concentrations were similar or lower than those 13 reported in a 2006-2007 study of California new homes built in 2002-2005. Mean and median 14 indoor concentrations were lower by 44% and 38% for formaldehyde and 44% and 54% for 15 PM2.5. Ventilation fans were operating in only 26% of homes when first visited and the control 16 switches in many homes did not have informative labels as required by building standards. 17 Keywords: ASHRAE 62.2, Healthy Efficient New Gas Home Study, Carbon dioxide, Fine 18 particulate matter, Formaldehyde, Nitrogen dioxide
19 Practical Implications
20 High performance home standards and building codes and regulations require mechanical 21 ventilation equipment to help manage moisture and air pollutants emitted indoors. This paper 22 demonstrates the success of a new construction residential ventilation requirement instituted in 23 the state of California in 2008, with almost all studied homes having compliant ventilation 24 equipment. The study found that the combination of mechanical ventilation and implementation 25 of a standard that reduced the allowable formaldehyde emissions from manufactured wood 26 products resulted in formaldehyde concentrations that were lower by 44% and 38% at mean and

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 3
1 median levels than in homes built prior to the standards. This study affirms that new homes can 2 be built to stringent efficiency standards while maintaining indoor air quality. 3 1. Introduction
4 Since 2008, California’s statewide residential building code has included requirements for 5 mechanical ventilation to protect indoor air quality (IAQ). Ventilation requirements were 6 implemented to mitigate any negative impacts of reducing uncontrolled air infiltration by 7 envelope air-sealing to reduce energy use. Lower air infiltration reduces dilution of pollutants 8 emitted inside the home, leading to higher concentrations if no other actions are taken. Although 9 mechanical ventilation in new homes has become commonplace in many developed countries, it 10 is uncommon in the U.S., particularly in single-family dwellings. Many state and local building 11 codes in the U.S. have implicitly relied on natural ventilation through leaky envelopes or for 12 occupants to manage IAQ using natural ventilation.
13 The presumption that occupants effectively utilize natural ventilation to manage moisture and 14 chronic exposure to formaldehyde and other pollutants from indoor sources in homes was 15 examined in two large studies conducted in California in the mid-2000s. In 2003, a mail-based 16 survey was sent to a statewide representative sample of homes built in 2002-2003 to query IAQ satisfaction, ventilation practices, activities, and equipment use that can impact IAQ1 17 . Based on 18 self-reported window use, the researchers assessed that most homes were substantially underventilated relative to the target of 0.35 h -1 19 , from the ASHRAE 62-1999 ventilation standard.
20 The California New Home Study (CNHS), conducted in 2006-2007, collected data in 108 homes built in 2002–20052 21 . The study included a thorough characterization of the building and thermal 22 and mechanical equipment; measurements of envelope and garage-to-house air leakage; an 23 occupant questionnaire that covered many of the same topics as the earlier mailed survey; 24 monitoring of window use over a week; and measurements of air exchange and various IAQ 25 parameters over a single 24-hour period. Sampling was roughly split between winter and summer

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 4
1 and between Northern and Southern California. Monitoring was repeated in 4 homes to 2 investigate day-to-day and seasonal variability. The study found that actual window use differed 3 from what participants reported generally for the season in which measurements were made (i.e., 4 52% under-reported and 8.3% over-reported), indicating that self-reported window use in the 5 mailout survey may have been biased low. The field study also found that air exchange rates (AERs) in the majority of new homes were below the target of 0.35 h -1 6 and that formaldehyde
7 was substantially above state exposure guidelines in almost all homes. The results of these two 8 studies suggested that new homes were not being adequately ventilated and that relying on 9 occupants and natural ventilation is not an acceptable approach. 10 Starting with the 2008 statewide Title 24 Building Standards, California instituted mechanical 11 ventilation requirements that were a hybrid of the requirements in the 2007 and 2010 versions of the ASHRAE Standard 62.2 for residential ventilation3 12 . The California standard required exhaust 13 fans in the kitchen and every bathroom and general ventilation for the dwelling unit that could be 14 satisfied with a continuous or intermittent system, utilizing exhaust, supply or balanced airflows. 15 A severe slowdown in new home starts in 2008-2010 delayed implementation as most homes 16 built during these years had been approved under the prior building code. The ventilation 17 requirements were not fully incorporated until at least 2010. 18 The Healthy Efficient New Gas Home (HENGH) study, described herein, was performed to 19 evaluate IAQ in California homes built to meet the 2008 building standards for ventilation. The 20 study focused on homes with natural gas because the sponsoring research program is financed by 21 a surcharge on investor-owned, gas utility customers and because gas cooking burners are an important source of air pollutants4, 5 22 . The study included a web-based survey of homes built since 23 2002, a simulation-based study of the energy impacts of ventilation, and the field study described in this paper. A report summarizing results of all three component studies is available6 24 . 25 This paper presents the methods and results of the HENGH field study and compares findings 26 from homes built with mechanical ventilation in 2011-2017 to the CNHS homes built in 2002-

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 5
1 2005 mostly without mechanical ventilation. Homes studied in HENGH also were built with materials that complied with an air toxic control measure (ATCM) for composite wood products7 2 3 that was implemented to reduce formaldehyde emissions. 4 The study goal was to provide empirical evidence of the impacts of ventilation and emission 5 standards in the most populous U.S. state. Findings may inform other states and nations 6 considering standards for residential mechanical ventilation. 7 2. Methods
8 2.1. Field Study Overview
9 Overview of Data Collection in Homes. The study was designed to assess how homes were 10 meeting the mechanical ventilation requirements and how the installed ventilation equipment 11 impacts indoor air quality. The study sought to characterize performance of installed equipment; 12 quantify the use of mechanical ventilation, gas cooking appliances and equipment that can 13 impact IAQ; measure key IAQ parameters over a weeklong monitoring period; and obtain data 14 from building occupants on IAQ and comfort satisfaction and IAQ-relevant activities. A core 15 goal was to evaluate IAQ in homes employing general (dwelling unit) mechanical ventilation but 16 not natural ventilation because the previous studies showed that many California homes do not 17 routinely open windows or doors for natural ventilation during one or more seasons of the year. 18 The study protocol was approved by the LBNL institutional review board. Methods are summarized in ensuing subsections and detailed protocols are available 8 19 . 20 Each study home was visited three times. On the first visit, the field team obtained written 21 consent, confirmed that code-required ventilation equipment was present and operable, and 22 started to record house, appliance, and mechanical equipment characteristics. A utility service 23 technician conducted a safety inspection of the gas appliances. In a few homes, the inspection 24 identified a minor issue that the technician resolved on the spot or during a follow-up visit, and 25 field measurements proceeded. During the second visit, the team completed equipment and

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1 house characterization, conducted ventilation diagnostics, installed air quality measurement 2 equipment indoors and outdoors, and installed devices to track ventilation and gas cooking 3 appliance use. The participant was provided with an activity log for each day of the study and 4 asked to partake in normal household activities with the exception that windows and doors 5 should not be used for routine ventilation. Most homes were monitored for seven days, five were 6 sampled for 8 days and one for 6 days. On the third visit, all IAQ and mechanical equipment 7 monitoring devices were removed, the survey and activity logs were collected and a $350 gift 8 card to a home improvement store was provided to the participant. 9 Eligibility and Recruitment. The study was limited to owner-occupied, detached California 10 houses, built 2011 or later, with gas appliances, mechanical ventilation, and no smoking allowed. 11 Homes had to be customers of SoCalGas or PG&E. Homes with unusual filtration or ventilation 12 systems were excluded. Code compliance records obtained for 23 homes verified they were 13 certified to meet 2008 or more recent standards. The presence of compliant or close to compliant 14 mechanical ventilation equipment was verified in all homes ultimately included in the study. 15 Most participants were recruited through postcards (see SI) mailed to addresses identified on a 16 real estate website (Zillow.com), targeting single-family, detached homes built 2011 or later. 17 Some participants learned of the study via referrals. Details about the number of respondents, 18 early withdraws and non-qualifying homes is provided in the SI. 19 2.2. Field Data Collection Procedures
20 House and Equipment Characterization. The information collected about each home and its 21 mechanical equipment is summarized in the SI.
22 Air Leakage. Air leakage of the building envelope and the forced air heating/cooling system 23 were measured with the DeltaQ test (ASTM-E1554-2013, Method A) using a TEC Minneapolis 24 Blower Door System with DG-700 digital manometer (energyconservatory.com). The test 25 quantifies air leakage of the forced air system to outside of the living space under normal

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1 operating conditions. Testing was conducted with software that automatically operated the 2 blower door fan through pressurization and depressurization, recorded airflow and pressure 3 differences, calculated envelope and duct leakage, and assessed if the measured parameters were 4 stable enough to provide both parameters. Air leakage was converted to air changes per hour at 5 50 Pa indoor-outdoor pressure difference (ACH50) using the estimated home volume. 6 Ventilation Airflows. Airflows of bath and laundry exhaust fans were measured using a TEC 7 Exhaust Fan Flow Meter (energyconservatory.com). Range hood airflows were measured using a balanced-pressure flow hood method described by Walker and Wray9 8 . A TEC Minneapolis Duct 9 Blaster, which is a calibrated, pressure-controlled, variable-speed fan, was connected to either 10 the exhaust inlet (preferred) or outlet. If connected at the inlet, a transition piece was adapted 11 onsite to cover the entire underside of the range hood or over-the-range microwave exhaust fan 12 (OTR). The flow through the Duct Blaster was adjusted to achieve neutral pressure between the 13 surrounding environment and the range hood inlet (or outlet) and airflow was determined from 14 the pre-calibrated fan speed versus airflow relationship. The measurement was repeated for the 15 lowest and highest settings and at least one medium setting if available. OTRs were tested in a 16 modified configuration: the top air inlet was covered with tape and the rate of air flowing into the 17 OTR was measured only at the bottom inlet. Subsequent testing at LBNL revealed that this 18 approach produces a biased measurement of total airflow occurring under the normal operating 19 configuration. Correction factors for most of the OTRs seen in the field were determined by 20 comparing the airflow into the bottom inlet when the top was taped to the total flow measured at 21 the exhaust duct outlet in laboratory experiments. The correction factors were applied to the field 22 measured airflows at each OTR setting.
23 Supply fan flow rates were not measured because the air inlets – usually on roofs or at the eave 24 level – could not be quickly and safely accessed by the field teams. It was also not feasible to 25 measure flows using in-duct velocity probes because the supply ducts were encased in spray 26 foam insulation in the attics. Supply airflows were inferred for two devices based on ratings.

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1 Equipment Usage Monitoring. Operation of exhaust fans, range hoods, and clothes dryers were 2 determined using one of the following: motor on/off sensor (Onset HOBO UX90-004), vane 3 anemometer (Digisense WD-20250-22), or plug load logger (Onset HOBO UX120-018). The 4 field team chose an appropriate sensor for each fan configuration. Range hoods or OTRs were 5 monitored with anemometers and the velocity at each setting was determined at installation to 6 enable tracking of airflows for AER calculations. State sensors (Onset HOBO UX90-001) were 7 used to monitor the most often used exterior doors. Although participants were asked to keep 8 doors and windows closed during monitoring, it was deemed valuable to check for any extended 9 natural ventilation that could affect pollutant measurements and patio doors were assessed as 10 most likely to be left open. Cooktop and oven use were monitored using Maxim iButton 11 DS1922T temperature sensors. Burner use was inferred from analysis of the temperature signals. 12 Air Quality Measurements. Air quality parameters were measured outdoors on the premises 13 and at several locations indoors, as summarized in Table 1. The central indoor site was generally 14 in a large open room on the first floor that included the kitchen and/or living room, but monitors 15 were not placed directly in the kitchen. Performance specifications of air quality measurement 16 devices are provided in Table 1 with additional information in Table S1 of the SI. Table S2 17 provides a summary comparison of the methods used to collect air quality data in HENGH and 18 the CNHS. At the HENGH central indoor site, equipment was mounted on a stacked crate 19 system that allowed free airflow. The outdoor monitoring station was mounted on a tripod with 20 air sampling at roughly 2 m height and the station placed at least 3 m from any exterior wall or 21 pollutant source such as a grill. Outdoor formaldehyde and NOX passive samplers were placed 22 inside a 10 cm diameter PVC cap for rain protection. The ES-642 photometer is housed in a 23 weatherproof enclosure that incorporates a sharp-cut cyclone to exclude particles larger than 2.5 24 m aerodynamic diameter and an inlet heater to maintain a minimum relative humidity in the 25 incoming sample stream; it also auto-zeroes each hour. Monitors used to collect time-resolved air 26 quality data were purchased new at the start of the study and thus expected to perform according

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1 to manufacturer specifications. Performance checks during the study are summarized below and 2 additional details are provided in the SI.
3 For the CO2 monitors, an initial visual check was conducted by operating all units together in the 4 warehouse used to prepare equipment for Northern California homes; but no formal calibration 5 was conducted at that time. In most homes, CO2 monitors were collocated during setup and 6 confirmed to read within 100 ppm of each other before deployment. Extech CO2 monitors were 7 checked against a calibrated PP Systems EGM-4 monitor during two collocation events at 8 LBNL, as described in the SI. Averaged over full spike-decay intervals, differences between 9 individual Extech units and the EGM-4 ranged from -20 ppm to 84 ppm. No corrections were 10 made to CO2 data and the possibility of larger deviations in some homes cannot be ruled out. 11 The ES-642 and BT-645 are aerosol photometers that translate light scattering measurements to 12 an estimated PM2.5 concentration based on a device-specific laboratory calibration using a 13 traceable reference of 0.6 m diameter polystyrene latex spheres. Since photometer response 14 varies with aerosol size distribution and optical properties, their accuracy for ambient (outdoor) or indoor PM2.5 can vary substantially as the qualities of the aerosol vary10-14 15 . The recommended 16 practice is to conduct a collocated gravimetric PM2.5 measurement and determine an environment 17 specific adjustment factor. In this study, we sought to check both the calibration factor and the 18 time-response of the Met One photometers by deploying Thermo pDR-1500 photometers with 19 onboard filter sampling indoors and outdoors at 8 homes. Due to power interruptions, valid 20 outdoor co-location data were obtained at only 5 homes and the results were too varied to 21 provide study-wide adjustment factors. To fill this gap, we obtained data from up to three 22 regulatory air quality monitoring stations closest to each house (Figure S1 of the SI) and 23 calculated outdoor PM2.5 for the study period at the house. As a second check on performance, at 24 most homes the indoor and outdoor photometers were operated side by side (typically outdoors) 25 for roughly an hour (Figure S2). Details about quality assurance for the air quality monitors are 26 provided in the SI.

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1 The standard software for the formaldehyde FM-801 monitor reports readings below 10 ppb as 2 “<LOD”. By special arrangement, GrayWolf provided modified software to enable us to access 3 device readings below this nominal detection limit, which we used in 25 homes. Prior research 4 indicates that the device may provide quantitative if more uncertain measurements below 10 ppb15. Some FM-801 formaldehyde was removed because of interference by high NO2 16 5 from
6 gas cooking burner use. Details about both adjustments are provided in the SI. 7 Duplicates and field blanks were collected to evaluate reliability for the passive samplers, and all 8 available duplicate samples were averaged to improve precision. Four Ogawa samplers prepared 9 according to manufacturer protocols were deployed at each home to measure NO2 and NOX: one 10 outdoors, two at the central indoor station (duplicates), and one field blank. The field blank was 11 opened either at the indoor or outdoor station, then packaged and stored in a refrigerator for the 12 monitoring week. At least four UMEx 100 formaldehyde samplers were deployed at each home:
13 one outdoors, two in the central indoor station (duplicates) and one in the bedroom. In most of 14 the sampled homes, a fifth sampler was opened indoors as a field blank, then immediately 15 packed and stored in a refrigerator during the monitoring week. The procedures used to analyze 16 passive samplers are summarized in the SI. The sampling rates for NO2 and NOX samples were 17 calculated based on measured average temperature and humidity according to Ogawa protocols. 18 For UMEx samplers we used the sampling rate of 20.4 mL/min recommended by the 19 manufacturer for air velocities <300 cm/min and 1 to 7 days of sampling. Offermann and 20 Hodgson have shown that sampling rates for the UMEx and other passive monitors start to drop sharply when air velocity falls below about 75 cm/min17 21 . Presenting measurements from six occupied houses and one unoccupied research house, Matthews et al.18 22 reported that such low air 23 velocities were infrequent. Since we did not measure velocities around the passive samplers and 24 did not verify measured concentrations with pumped samples, it is possible that sampling rates 25 could have been lower than the assumed standard values at some times in some homes.

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1 Survey and Activity Log. Participants were asked to complete a survey about the household 2 occupants and their general activities that impact ventilation and IAQ and also to complete an 3 activity log for each day of monitoring. The survey was a condensed version of the online survey 4 used to collect data about California detached homes built since 2002. Recruitment for the online 5 survey was conducted primarily through emails sent by SoCalGas to customers who lived in 6 homes that use natural gas and were thought to meet the requirement of being constructed in 7 2002 or later. A summary of findings from the survey is provided in the HENGH final project report6 8 . The abridged survey tool used for the field study and the daily activity log are included 9 in the SI to this paper.
10 Calculated Outdoor Air Exchange Rate (AER). The rate of outdoor air exchange – including 11 both mechanical ventilation and air infiltration – was calculated minute-by-minute in each home 12 following the Enhanced Model described in the 2017 ASHRAE Handbook– Fundamentals, as 13 summarized in the SI. The calculation assumed that windows and doors were closed throughout 14 the monitoring week (as required), so natural ventilation was negligible. The AER over the full 15 monitoring period in each home was calculated as the harmonic mean of the minute-by-minute estimates. Measured AERs in CNHS houses2 16 that did not have mechanical ventilation and did 17 not open windows were analyzed to assess the accuracy of the infiltration portion of the AER 18 calculation, as described in the SI.
19 3. Results and Discussion
20 3.1. Locations and Seasons of Home Visits
21 The field study collected data from 48 homes in the San Francisco Bay Area and Central Valley 22 regions and 22 homes in Southern California, as shown in Figure 1. The breakdown by gas utility 23 service territory, California climate zone, and city is provided in Table S3. Sampling occurred 24 throughout the year, with slightly more homes visited in the months corresponding to summer 25 seasonal conditions (June–September, n=27 homes) than each of the other seasons, in which 13

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1 to 16 homes were studied (Table S4). None of the homes were within 300 m of a freeway, 2 highway, or high-volume arterial road.
3 3.2. House and Household Characteristics
4 Characteristics of HENGH homes with selected comparisons to the CNHS and California data 5 from the 2017 American Housing Study (AHS) are reported in SI Tables S5–S15 and Table 2. 6 HENGH and CNHS samples had similar distributions of home size and occupant density; but 7 HENGH homes were newer when tested and more commonly had gas cooking appliances (Table 8 2). HENGH included one 2.5-story, 42 two-story, and 27 one-story houses (Table S8) and all but 9 one had an attached garage. HENGH homes mostly had three (n=20), four (n=28) or five (n=17) 10 bedrooms and almost all had multiple bathrooms (Tables S9–S10). Thirty-two HENGH homes 11 had vented gas fireplaces (Table S11).
12 HENGH households were similar in size to the AHS, with slightly more having 1-2 occupants 13 (46% vs. 41%), fewer with 3-4 occupants (34% vs. 42%) and similar 5+ occupants (17% vs. 14 15%) (Table S12). HENGH households had similar age demographics as the AHS, with 40% of 15 each having at least one resident under age 18 and 26-28% with at least one resident aged 65 or 16 older (Table S13). Relative to the AHS, the HENGH sample was skewed in terms of income and 17 education. In HENGH, 88% of the 66 participants who provided the information had a household 18 income of $100,000 or greater; in the AHS sample, only 60% reported such income (Table S14). 19 Of the 67 HENGH heads of household that reported education level, 88% had a college degree 20 and 54% had a graduate or professional degree; in the AHS, 56% had someone with a college 21 degree and 26% had someone with a graduate or professional degree (Table S15). 22 With the important caveat that the CNHS asked about medically diagnosed conditions and 23 HENGH asked simply about the conditions, HENGH households more commonly reported 24 someone with allergies (56% vs. 36%) or asthma (26% vs. 16%); CNHS also reported chemical 25 sensitivity in 3.7% of homes (HENGH survey did not ask about this condition).

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1 3.3. Envelope Air Tightness
2 The distribution of measured envelope air tightness, expressed as the air changes per hour at a 50 3 Pascal indoor-outdoor pressure difference (ACH50), are shown in Figure S3. The mean, median, and 10th–90th 4 range of envelope air tightness from depressurization tests were 4.6, 4.4, and 3.4– 5 6.0 ACH50. Measured air leakage under pressurization was higher than depressurization by 20% 6 on average due to “valving” of some air leakage pathways, e.g., from exhaust fan backdraft 7 dampers being pushed open during pressurization. Only four homes had envelope leakage less 8 than 3 ACH50, the level required for compliance with the 2018 International Energy 9 Conservation Code. Overall, HENGH homes had air leakage values similar to California homes 10 built in the early 2000s, as reported in the online residential diagnostics database (resdb.lbl.gov)19 11 and in the CNHS, which had a mean ACH50 of 4.8. 12 3.4. Ventilation and Filtration Equipment
13 All 70 HENGH homes had ventilation equipment that was mostly or completely compliant with 14 the statewide standards. As summarized in Table S16, dwelling unit ventilation was provided by 15 an exhaust system in 64 homes and by a supply system in 6 homes. Fifty-five of the exhaust 16 systems used a continuous fan and 43 of those exhausted air from the laundry room; the others 17 exhausted from a bathroom. Three of the exhaust systems had remote fans located in the attic 18 and the others were upgraded laundry or bath exhaust fans. All supply systems were integrated 19 into the central forced air heating and cooling system; four had inline fans and two relied on the 20 central system fan operating on a timer to pull in outdoor air through a duct connecting the return 21 to the outdoors. In all but two of the homes with measured airflow, the flow exceeded the code minimum requirement. The mean minimum requirement was 107 m3 h -1 22 and the mean installed
flow was 163 m3 h
-1 23 , about 50% higher. In many homes, the “extra” airflow could be explained 24 by use of a common fan size set to maximum capacity, i.e., not adjusted down to meet minimum 25 requirements. Very importantly, the general ventilation equipment was running in only 26% of 26 homes (18/70) when the field researcher(s) arrived for the initial visit. Systems with easily

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1 understandable signage at the power switch for the system were much more likely to be 2 operating (see Table S17).
3 All of the homes had exhaust fans in the kitchen and in each bathroom, as required by the 4 standards. Kitchen ventilation was provided by a range hood in 32 homes and an over the range 5 (OTR) microwave in 38 homes. Twenty-two (69%) of the range hoods moved the required 50 L s
-1 6 or 100 cfm on the lowest speed setting, seven met the standard on a medium setting, and three 7 did so only at the highest setting. Of the 38 OTRs for which airflows were measured in homes, 8 method correction factors were obtained and applied to 22 devices. For this group, the estimated 9 airflow met the code requirement for 8 installed units (36%) on the lowest setting, 14 (64%) on a 10 medium or higher setting, and 20 (91%) on high or boost setting. The setting needed to produce 11 the required airflow is important because the code also requires that the fan operate at a sound 12 level of 3 sone or less, with the rationale that kitchen exhaust may not be used as needed if it is too loud. Over 85% of the full bathrooms had exhaust fans that met the requirement of 25 L s -1 13
14 or 50 cfm, as shown in Figure S4. Exhaust fans in the toilet room or shower of the master 15 bathroom suite are not required to meet the airflow standard if the main exhaust fan in the bathroom suite does so. These fans had lower measured airflows and only 60% met the 25 L s-1 16 benchmark. The median exhaust flows were 41, 37 and 31 L s -1 17 (87, 78 and 65 cfm) for master
18 bath, other bathroom and toilet/shower compartments. 19 Of the 69 homes with a forced air thermal conditioning system, 22 had only one filter, 34 had 20 two filters, 10 had three filters and 3 had four or more filters (with one filter per return duct). As 21 shown in Table S18, 96% (107/111) of the filters for which a performance rating could be 22 determined were MERV8 or better and 30% (33/111) were MERV11 or better. In the CNHS, 23 filter ratings were determined in 97 of the 108 homes: 49% (48) had MERV8 or better and 32% 24 (31) had MERV11 or better. In HENGH homes, we were able to determine the last date of 25 change for 85 filters: 58% (49) had been changed within the last 6 months, 22% (19) had not 26 been changed in the past year and 11 of those had never been changed (Table S19). Table S20

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1 shows that 20 homes had filters that were clean or like new, 29 homes had filters that appeared 2 used or somewhat loaded, and 18 homes had at least one very dirty filter. There were a few 3 homes in which, at the owner’s request, the research team replaced (n=2) or installed (n=1) air 4 filters in the forced air systems during the first or second field visit, prior to monitoring. 5 3.5. Ventilation During the Week of Monitoring
6 Field teams set dwelling unit mechanical ventilation systems to operate during the monitoring 7 period in each home. The two homes with supply ventilation powered by their central thermal 8 conditioning system fans were ventilated during the study by running their laundry exhaust fans 9 continuously. The average air exchange rate (AER) resulting from infiltration and mechanical 10 equipment operating during the monitoring week was estimated for 63 homes, with results 11 provided in Figure S5. AER was not estimated for four homes with supply ventilation fans 12 because the system airflow could not be measured and for three homes that did not have a valid 13 envelope air leakage measurement, which is needed to calculate infiltration. Five homes that had 14 their dwelling unit exhaust fans stopped (presumably turned off by occupants) during the week had low calculated AERs: 0.07–0.15 h
-1 15 . A sixth home, which had an intermittent exhaust fan 16 that was not programmed to provide sufficient ventilation (by error of the field team), also had a low AER, of 0.06 h
-1 17 . For the 57 homes that had measured airtightness and mechanical 18 ventilation system airflows and their systems operated throughout the week of monitoring, the mean, median and 10th–90th 19 percentiles of the estimated infiltration + mechanical AERs were

0.33, 0.30, and 0.20–0.46 h
-1 20 . Mechanical ventilation provided substantially higher outdoor air 21 exchange rates than would have occurred by infiltration only, as shown in Figure S6. 22 The AERs estimated for HENGH homes operating with code-compliant systems and windows 23 presumed closed were marginally higher than in the CNHS (before ventilation was required), which reported sample median AERs of 0.26 h
-1 24 for 107 homes measured during a single
monitoring day and 0.24 h
-1 25 for 21 homes measured over a 2-week period that included window 26 use. Twenty-two CNHS homes had mechanical equipment to provide dwelling unit ventilation;

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1 these included 8 with heat recovery ventilators (HRV) and 14 with ducts connecting the forced 2 air heating/cooling system return duct to the outdoors. Of the 14 with outdoor air ducts, only 4 3 had controllers to operate the FAU for mechanical ventilation when no heating or cooling was 4 needed. During the day of CNHS monitoring, all of the HRVs but only 34% of the outdoor5 connected FAU systems met the ASHRAE 62.2-2004 standard applicable at the time. 6 In several of the HENGH study homes, the actual outdoor air exchange over the week was likely 7 higher than the calculated values owing to use of natural ventilation. In six homes, the occupants 8 reported opening the house-to-patio and/or garage door(s) for more than 3 h per day on average. 9 The calculated AERs also could be roughly 20% higher based on the potential bias in infiltration 10 calculation indicated by the analysis of CNHS data from homes without mechanical ventilation. 11 3.6. Sources of Air Pollutants Reported in the General Survey 12 Almost all HENGH homes reported being completely smoke free; one reported that smoking 13 occurred a few times per year and one acknowledged informally that a family member smoked 14 daily in a bedroom, with the window open. Occasional candle burning was fairly common, with 15 16 HENGH participants reporting candle use a few times per month, 11 using a few times per 16 week, and 5 every day (Table S21). Thirty-four households had at least one furry pet and twelve 17 reported two or more; 20 reported no pets and 16 did not respond to the pet question (Table S22). 18 3.7. Occupancy and Activities During the Week of Monitoring 19 Data from the HENGH daily activity logs are provided for occupancy (Tables S23–S24) and 20 cooking (Tables S25–S27). Most of the homes had one to three occupants at home at any given 21 time when occupied and 88% of those reporting were occupied during time intervals totaling 16 22 or more hours per day on average. Thirty-four of 68 homes with daily log data reported using the 23 cooktop at least 7–14 times per week; oven use was less common. Cooktop use events were <30 24 min on average in most homes. Oven use was typically longer. Cooking and other activities 25 reported in the CNHS homes are provided in Table S28.

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1 3.8. Air Pollutant Concentrations: Formaldehyde
2 Multiple measurements of formaldehyde in each HENGH home indicated very good sampling 3 precision and mostly similar concentrations in the master bedroom and central indoor sampling 4 location. The average mass on field blanks corresponded to 0.6 ppb for a 7-day collection period 5 and the 66 paired indoor samples agreed to within 1.0 ppb on average (median = 0.7 ppb). 6 Sample-period averaged concentrations calculated from half-hourly resolved GrayWolf (Shinyei) 7 multimode monitor data agreed well with the time-integrated sampler results as summarized in 8 Table S29 of the SI. Figure 2 presents the formaldehyde concentrations measured in the master 9 bedrooms and central indoor locations of each home by UMEx passive sampler. Among the 66 10 homes with valid samples in both locations, formaldehyde in the bedroom was >10% higher than in the living room in 20 homes and less than 90% in 7 homes. The median and 10th–90th 11 ratios of 12 bedroom to living room concentrations were 1.02 and 0.90–1.27. Period-averaged formaldehyde 13 determined by the multimode monitor indicated a similar trend of the master bedroom having 14 higher concentrations than the central area more frequently than the opposite. And the overnight 15 concentration in the bedroom was even higher than the period-average at that location. (See SI 16 for details). These findings suggest that for many people exposure to formaldehyde at home may 17 be higher than indicated by average concentrations at a central indoor site. 18 Figure 3 shows that homes built in 2011–2017 and mostly operating with mechanical ventilation 19 (HENGH) had formaldehyde concentrations substantially lower than those built in 2002-2005 20 and mostly not using mechanical ventilation (CNHS). Mean and median formaldehyde levels in 21 HENGH homes were 44% and 38% lower than in CNHS (Table 3). Differences between the 22 HENGH and CNHS indoor formaldehyde concentrations were found to be significant based on a 23 two-tailed Student’s t-test with equal variance comparing log-transformed concentrations (p24 value = 3.4e-8) and the nonparametric Mann-Whitney test (p-value = 1.5e-7). The highest 25 formaldehyde measured in any home in the current study was 44 ppb while 28% of the CNHS 26 homes had a formaldehyde concentration over 44 ppb. Indoor emissions were the primary source

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1 in both studies; but based on median indoor and outdoor values, the fraction contributed by 2 outdoor air increased from 6% in the mid-2000s to 15% more recently. 3 Formaldehyde levels in HENGH homes were all well below the World Health Organization 4 (WHO) indoor air guideline of 80 ppb and also below non-U.S. national guideline levels as summarized by Salthammer 20. However, all homes were still above the 7 ppb (9 g/m3 5 ) Chronic 6 Reference Exposure Level set by the California Office of Environmental Health Hazard 7 Assessment, which is the applicable target in California. 8 The substantial reduction in formaldehyde compared to the CNHS a decade earlier appears to 9 result both from fewer homes being severely under-ventilated and from lower emissions. For 32 CNHS homes with measured air exchange rates below 0.2 h-1 10 , mean and median formaldehyde 11 concentrations were 57 and 45 ppb. By contrast, in the HENGH dataset, only eight of the 63 homes for which overall AER was estimated had outdoor AERs below 0.2 h-1 12 ; and the mean and 13 median formaldehyde concentrations for these homes were 25 and 23 ppb. 14 Formaldehyde emission rates were calculated for 61 HENGH homes using the measured 15 concentrations and estimated AERs. The median and mean emission rates were 5.8 and 6.1 g/m3-h compared to median and mean values of 11 and 13 g/m3 16 -h calculated from 99 homes 17 with the required component data in CNHS (Table 45 of Offermann et al., 2009). CNHS homes had more varied formaldehyde emission rates, with a 10th to 90th 18 percentile range of 4.0 to 23 g/m3-h whereas the range for HENGH homes was 2.8 to 8.3 g/m3 19 -h. For this comparison, it is 20 important to note that the CNHS measured AERs with a PFT tracer gas whereas the HENGH 21 AERs were estimated by combining the measured mechanical ventilation airflows and calculated 22 air infiltration assuming no contributions from open windows or door. To the extent that actual 23 AERs in HENGH homes were higher than calculated – e.g. from a possible ~20% bias in the 24 calculated air exchange rates as discussed in the SI, or from use of windows and doors – the 25 formaldehyde emission rates in HENGH homes would have been higher than stated above.

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1 3.9. Air Pollutant Concentrations: Fine Particulate Matter (PM2.5) 2 Time-resolved PM2.5 concentrations reported by indoor photometers were adjusted based on 3 comparison to gravimetric analysis of filter samples collected in 8 homes (Table S30). Indoor 4 photometer measurements were adjusted by a multiplier of 1.23 for the BT-645, and 0.90 for the 5 pDR-1500. Aside from the gravimetric adjustment, pDR-1500 also measured time-resolved 6 PM2.5 for comparison with BT-645. Hourly indoor readings from the 8 homes collected by the two photometers were highly correlated (R
2 7 = 0.96-0.99) and, after applying the respective
multipliers, agreed to within 1 g/m3for 84% of the hourly readings, and 2 g/m3 8 for 96% of 9 the hourly readings.
10 Distributions of indoor PM2.5 in HENGH and CNHS are shown in Figure 4. Mean and median 11 indoor PM2.5 concentrations in HENGH were 44% and 54% lower than in CNHS homes (Table 12 3). Even with uncertainty in the photometer adjustment factors, these data indicate substantially 13 lower indoor PM2.5 in the more recently constructed homes. The difference in log-transformed 14 indoor PM2.5 concentrations measured by the two studies are statistically significant using 15 Student’s t-test (p-value = 2e-6) and nonparametric Mann-Whitney test (p-value = 2e-5).

Since outdoor air is a major source of PM2.5 inside U.S. homes21-25 16 , it is important to consider if 17 the observed difference could be entirely attributed to lower PM2.5 outdoors during HENGH. The 18 CNHS reported 11 samples of outdoor PM2.5; based on the clustering sampling approach used in 19 that study, those measurements represent 28 homes. For the HENGH study, the 5 weeks of 20 collocated outdoor photometer and gravimetric samples had such varied ratios (see Table S30 of 21 SI) that they could not be used to adjust all of the outdoor photometer data. Data from regulatory 22 ambient air monitoring stations nearby to HENGH homes provide a second set of estimates of 23 areawide outdoor PM2.5 during the study. Table S31 and Figure S7 of the SI show that outdoor 24 PM2.5 estimates from the air monitoring stations are higher than those from unadjusted outdoor 25 photometer data. This is directionally consistent with outdoor photometer reading lower than the 26 indoor photometer in side-by-side monitoring and suggests that the outdoor photometer may be

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1 understating the outdoor PM2.5. Summary statistics of outdoor PM2.5 from both data sets applied 2 for the HENGH study are compared to CNHS data in Table 3. While limitations of both data sets 3 make the comparison uncertain, the results in Table 3 do not indicate substantially lower PM2.5 4 outside of HENGH versus CNHS homes. The lower PM2.5 inside HENGH homes can therefore 5 not be attributed to lower outdoor PM2.5.
6 The lower indoor PM2.5 in HENGH homes could result from reduced penetration of particles 7 during air infiltration, lower indoor emissions (from cooking, candles, cleaning, etc.), more 8 effective kitchen ventilation, and/or improved filtration. Reduced particle entry during air 9 infiltration is not likely a major factor as the envelope air tightness was very similar in the two 10 samples and the higher median outdoor air exchange rates in the HENGH study would tend to 11 slightly increase indoor concentrations of outdoor particles as higher AERs bring in outdoor air 12 more quickly and leave less time for particles to deposit onto indoor surfaces. 13 Assessing the impact of filtration overall requires consideration of filter quality, airflow and 14 operating cycles of the central forced air system, and use of portable air filtration units. While the 15 full analysis is beyond the scope of this paper, it was reported above that HENGH homes more 16 commonly had at least a medium performance (MERV8) filter compared to CNHS homes. There 17 also may have been more portable air cleaner use in HENGH homes. Of the 64 HENGH 18 participants who answered the question, 14 (22%) reported using a standalone air cleaner. Air 19 cleaner use was self-reported in 17% of CNHS homes and 15% of respondents to the statewide survey in 2002-4
1 20 .
21 While it is difficult to compare the impact of all particle emitting activities – since emissions 22 vary so widely even for a defined activity – we can at least compare the frequency of cooking 23 and range hood use. In the CNHS study, during the day of IAQ monitoring, 87 homes (81%) 24 reported at least one use of the cooktop or oven and 81 (75%) reported at least one cooking event 25 involving frying, sautéing, baking or broiling. Despite this relatively high frequency of cooking 26 that can emit substantial quantities of PM2.5, only 22% of the CNHS occupant activity logs

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1 reported any range hood use during the day of IAQ measurements and 44% reported some range 2 hood use during the prior week. Over the roughly one-week monitoring in HENGH homes, 34 of 3 the 68 submitted activity logs (50%) reported cooking with the cooktop or oven at least 7 or 4 more times during the week, i.e. once per day on average. The HENGH activity log did not ask 5 about the type of cooking. In the general survey responses, 50% of HENGH participants reported 6 using their range hood “most of the time” (4 of 5 times) or more and another 23% reported using 7 the range hood “sometimes” (2–3 out of 5 times). Initial analysis of cooktop temperature and 8 range hood/OTR use data indicate that kitchen ventilation was employed in some capacity during 9 roughly 29% of cooktop uses and 22% of oven uses and actual use during the monitored week 10 was much less than usage reported by survey. The range hood was operated for most or all of the 11 duration of cooktop use during 8% of cooktop use events and 3% of oven use events. 12 3.10. Air Pollutant Concentrations: Nitrogen Dioxide and Nitric Oxide 13 Distributions of NO2 concentrations inside HENGH and CNHS homes are presented in Figure 5 14 and summary statistics are provided in Table 3. The distributions were not significantly different 15 based on the nonparametric Mann-Whitney test (p-value = 0.08) and the means of the log16 transformed data were not statistically different using the Student’s t-test (p-value = 0.15). This 17 occurred despite all HENGH homes having natural gas cooktops (compared to just 2% of CNHS 18 homes) and outdoor NO2 being higher in HENGH. The higher median indoor NO2 in HENGH 19 may be misleading as the CNHS median was in the group of data set as half of the quantitation 20 limit and the outdoor median for CNHS was lower (though uncertain for the sample as NO2 was 21 sampled outside of only a subset of homes). Differences in NO2 between HENGH and CNHS 22 homes were much smaller than those reported for homes with gas versus electric cooking in a recent study of mostly older and smaller California homes 5 23 . The highest weekly averaged NO2 24 measured in a HENGH home was below the California annual average standard of 30 ppb and 25 less than half of the U.S. annual air quality standard of 53 ppb. Figure S8 shows that for NO, 26 indoor concentrations were almost always higher than outdoors, as indoor emissions added to the

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1 NO coming from outdoors. For NO2, deposition indoors resulted in indoor concentrations being 2 lower than outdoors in many homes.
3 3.11. Air Pollutant Concentrations: Carbon Dioxide as Indicator of Adequate Ventilation 4 Overall, time-averaged CO2 levels measured in HENGH and CNHS homes were similar, as presented in Table 3. The one substantive difference – at the 90th 5 percentile – aligns with 6 mechanical ventilation systems in HENGH homes more consistently providing outdoor air to 7 dilute occupant emissions of CO2.
8 Within HENGH homes, CO2 concentrations varied spatially (Figure 6). The highest time9 averaged concentrations were in the master bedroom and concentrations in other bedrooms were 10 higher than in the main indoor living space.
11 CO2 concentrations also varied in time, with the highest concentrations occurring overnight in 12 bedrooms. Figure 7 shows the distributions of average CO2 concentrations in each room, looking 13 only at data from midnight to 5 am, and SI Figure S9 presents overnight CO2 concentrations 14 measured in the main indoor location and master bedrooms of the same houses. These results 15 indicate that CO2 in HENGH bedrooms did not reach the levels that have been reported to affect sleep or next day alertness26, 27 16 .
17 3.12. Satisfaction and Discomfort with Indoor Environmental Conditions 18 Sixty-eight of the 70 HENGH study participants provided responses to survey questions about 19 their satisfaction with environmental conditions in the home. Responding to the question “To 20 what extent are you satisfied or dissatisfied with the indoor air quality in your home?”, 68% 21 (n=46) selected one of four levels indicating positive satisfaction, 24% (n=16) selected neutral, 22 and 9% (n=6) marked one of four levels indicating dissatisfaction. These results are very similar 23 to those obtained from 2765 respondents to the online survey of people living in California 24 homes built before ventilation standards were in place. That survey, conducted in 2014, was 25 open to occupants of California homes built since 2002; yet almost all respondents lived in

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homes built before 2011 and located in the SoCalGas service territory of Southern California6 1 . In 2 the online survey, 69% indicated positive satisfaction, 21% were neutral, and 10% indicated 3 dissatisfaction with their IAQ. Among 68 field study respondents, 51% were satisfied with the 4 air quality outside of their homes, 17% were neutral and 32% were dissatisfied. These totals are 5 also similar to the online survey, for which 47% were satisfied, 27% were neutral and 26% were 6 dissatisfied with their outdoor air. When asked “How would rate you rate your home in 7 protecting you from outdoor air pollution?” 62% of responding field study participants were 8 satisfied, 31% were neutral and 7% were dissatisfied. The CNHS did not report results for IAQ 9 satisfaction and the survey reported by Piazza asked about “acceptability” of indoor air quality, 10 rather than “satisfaction”, which is not directly translatable. 11 The survey of HENGH participants – both field study and online – also asked about the 12 frequency of specific environmental discomforts, offering options of “never”, “few times a 13 year”, “few times a month”, “few times a week”, and “every day”. The CNHS study asked 14 participants if they experienced discomfort during the preceding week. Table 4 shows that 15 specific discomfort conditions were generally similar in the two studies, with the exception that 16 21% of HENGH participants reported not enough air movement compared to 12% of CNHS 17 participants experiencing the air as “too stagnant” in the week prior. The robustness of that 18 difference is unclear as 18% of the survey respondents from homes built around the same time as 19 those in the CNHS also expressed frequent dissatisfaction with air movement. 20 Survey responses from the field study were analyzed to evaluate if environmental satisfaction 21 differed in homes that had MV systems operating or not operating when the research team first 22 arrived to study homes. Results provided in Tables S32 to S34 indicate no statistically significant 23 associations with satisfaction for air quality, seasonal temperature, or other environmental 24 conditions (air movement, dryness or dampness, musty odors).

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1 3.13. Comparison to Other Studies of Ventilation and IAQ in Recent Construction Homes 2 There have been few large field studies examining the impact of mechanical ventilation on IAQ 3 in recently constructed homes. The study that most directly addressed this topic examined 62 4 homes built in 2010-2012 to an Austrian efficiency standard that included general mechanical 5 ventilation with heat recovery (MVHR) and 61 homes constructed during the same years using normal building standards without mechanical ventilation28 6 . The study measured IAQ parameters 7 roughly 3 months and 1 year after occupancy and used interviews to collect data about health symptoms and perceptions of IAQ and comfort29 8 . The efficient homes with MVHR had lower 9 concentrations of total volatile organic compounds (TVOC), formaldehyde, saturated acyclic aliphatic aldehydes, CO2, and radon28 10 . While there were not significant differences in self11 reported overall health status or for most symptoms, occupants of the efficient, ventilated homes 12 rated their environmental quality higher by more frequently noting positive attributes (pleasant, 13 clean, fresh and fragrant) and less frequently perceiving negative attributes (stale, stuffy, stagnant, bad smelling or smoky)29 14 .

The effects of improving ventilation in existing airtight homes was reported by Lajoie et al.30 15 in a 16 study that added mechanical ventilation with heat or enthalpy recovery to 43 of 83 Quebec area 17 homes of asthmatic children that were verified to be under-ventilated. IAQ parameters and the 18 children’s respiratory health were monitored over two years. The homes with added mechanical 19 ventilation had several statistically significant and substantial (>25%) improvements including 20 higher outdoor air exchange and lower CO2, formaldehyde, styrene, limonene and mold spores; 21 but also had higher indoor NO2 and di(2-ethylhexyl) phthalate. 22 Several studies have reported on the installed performance of mechanical ventilation systems in 23 modern homes. A study of mechanical ventilation systems in 299 Dutch homes completed in 24 2006-2009 conducted visual inspections, measured ventilation rates per room and equipment noise, and asked occupants their perceptions of their indoor air quality31 25 . Issues identified in 26 many homes included ventilation rates below and noise levels above building code requirements,

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1 blocked supply vents, and absence of required controls. Problems occurred during installations, maintenance and operations. A study in Belgium32 2 conducted mechanical ventilation system 3 diagnostics and measured carbon dioxide, temperature and humidity levels in 39 standard 4 construction homes built in 2007-2008 with wet room exhaust ventilation and trickle vent 5 supplies (and mean air leakage of 3 ACH50), 23 similarly tight (2 ACH50) low-energy homes 6 with MVHR, and 16 passive houses (0.5 ACH50) with MVHR. Installed equipment in many of 7 the homes did not achieve the required airflows at any setting and occupants generally operated 8 the systems at lower settings, leading to large differences between actual and design airflows. 9 Humidity and CO2 measurements showed some differences between groups of homes but none 10 indicated substantial problems. In a study of 29 homes in the U.S. state of Washington, which 11 has required mechanical ventilation for many years, researchers reported that most had systems that were set, or that could be set to comply with the standard33 12 . In many of the homes the MV 13 systems were not operating according to design standards when researchers first arrived. A study of mechanical ventilation systems installed in 21 homes in the U.S. state of Florida34 14 , which did 15 not require such systems at the time, found that only 12 were capable of operating and actual 16 airflows generally were well below design targets. These two U.S. studies reported problems 17 with installation (disconnected duct, blocked vent, poorly hung ducts, inoperable outdoor air 18 exhaust duct damper, ERV/HRV system installed backward) and operations and maintenance 19 (fan turned off, dirty filters, controller set to inadequate runtime fraction). 20 Among the air pollutants measured in HENGH, the most direct comparisons to prior U.S. studies 21 can be made for formaldehyde. HENGH homes had substantially lower formaldehyde than a 22 sample of homes constructed in the late 2000s with low-VOC flooring and paints along with mechanical ventilation; those homes had mean formaldehyde of 27 ppb (33 g m-3 23 ) at adjusted conditions of 23ºC, 43% RH, and 2.25 years old35 24 . In a study in the U.S. state of Arizona, 25 apartments that were renovated in 2011 with low-VOC materials and mechanical ventilation had 26 reported mean(SD) and median formaldehyde levels of 27(7) ppb and 26 ppb roughly 1 year

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after renovations36 1 . These levels represented a decrease from pre-retrofit formaldehyde of 39(11) 2 ppb and 38 ppb (ibid). The higher concentrations measured in these studies relative to HENGH 3 could result from sampling occurring only during daytime hours in the summer season, a time at 4 which emissions are expected to be higher than concentrations measured over full diurnal cycles and varied seasons37 5 . The lower concentrations in HENGH homes could also result in part from 6 lower emissions resulting from the California air toxic control measure. 7 3.14. Limitations
8 The samples of homes included in the HENGH and CNHS studies may not accurately represent 9 the population of recently constructed homes in the state now or in the mid-2000s. Relative to 10 the general population of new home owners, HENGH households were biased toward higher 11 income and higher education and potentially also toward higher interest in IAQ (since they 12 volunteered to participate in the study). The impact of these biases is not known. 13 Even within the homes studied, the air quality measured in both HENGH and CNHS may not 14 accurately reflect average conditions. In the HENGH study, IAQ was measured while homes 15 were operated without natural ventilation (i.e., with occupants agreeing to keep windows and 16 doors closed) and with mechanical ventilation systems set to operate. This mode likely does not 17 represent conditions in newer California homes throughout the year, especially since we found 18 that general ventilation systems were not operating in 74% of the homes studied. This was not an 19 issue for CNHS because occupants were asked to use natural ventilation as normal. For both 20 studies, the act of participating could have changed occupant activities that impact indoor air 21 quality. Since CNHS sampling occurred over a single 24 h period, occupant routines may have 22 been impacted by modified schedules to accommodate sampling equipment installation, removal 23 and diagnostics on subsequent days. The processes of completing surveys and activity logs and 24 having monitoring equipment in the homes could have impacted behaviors in both studies. 25 Between study differences in recruitment, sample design and measurement methods also may 26 have impacted the relative results in HENGH and CNHS.

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1 For the HENGH study, ventilation rates were not directly measured as they were in the CNHS. 2 The ventilation estimated by combining calculated infiltration rates and measured mechanical 3 airflows in the HENGH study would be biased low in any homes with sustained opening of 4 doors and/or windows for natural ventilation.
5 4. Conclusions
6 Measurements were conducted in 70 single-family, detached homes constructed in 2011–2017 7 under California building standards that require mechanical ventilation and a separate regulation 8 that limits formaldehyde emissions from composite wood products. All homes had mechanical 9 ventilation equipment that was mostly or completely compliant with the requirements. With the 10 general mechanical systems operating and most homes not using any natural ventilation, indoor 11 air pollutant levels were generally lower than those measured in a prior study of otherwise 12 similar California homes built before the ventilation and material emission standards took effect. 13 The recently constructed homes had somewhat lower PM2.5, much lower formaldehyde, and 14 slightly higher NO2 despite having gas cooking burners whereas homes in the prior study had 15 electric cooking. IAQ satisfaction was also similar in the newer homes as compared to homes 16 built in years prior. These results indicate the success of standards that limit formaldehyde 17 emissions and require ventilation systems to maintain acceptable IAQ. 18

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Table 1. Measured Air Quality Parameters1 1
Measurement
Device
ParametersAccuracy1 Res. Sampling
Locations
Met One ES-642
Photometer
PM2.5 ± 5% traceable standard with

0.6 um PSL
1-min Outdoor
Met One BT-645
Photometer
1-min Indoor: central
Extech SD-800
Infrared
CO2,
T,
RH
±40 ppm <1000; ±5%
>1000ppm; 2
±0.8°C
±4% below 70%; 4% of reading
+ 1% for 70–90% range
1-min Indoor: central,
master BR, other BR
Ogawa Passive
Samplers
NO2 and
NOX
Field validation3: 7 d rel. dev.:
3±2% NO2 at 11-37 ppb; 4±3%
NOX at 16-85 ppb; 10±9%
(NOX-NO2) at 4-56 ppb
1-week Outdoor;
Indoor: central
Aeroqual 500 Series
Electrochemical
NO2 ± 0.02 ppm within 0 to 0.2 ppm
range
1-min Indoor: central
GrayWolf FM-801
(Shinyei Multimode)
HCHO ± 4 ppb <40 ppb,
± 10% of reading ≥40 ppb
30-min Indoor: central,
master BR
SKC UMEx-100
Passive
HCHO ± 25%, exceeds OSHA
requirements
1-week Outdoor; Indoor:
central, master BR
Onset HOBO
UX100-011
Onset HOBO U23
Pro v2
T, RH ±0.21°C from 0° to 50°C
±2.5% from 10% to 90%; up to
±3.5% at 25°C including
hysteresis
1-min Indoor: central
(UX100-011);
Outdoor (U23);
1 2 Based on manufacturer specifications unless noted otherwise. Table S1 in Supporting Information provides some additional information. 3
2 Manufacturer indicates ± 40 ppm for CO2<1000 ppm; the cited value of ±50 ppm reflects our group’s experience (unpublished) with the monitors. 3 Field validation in California reported by Singer et al.38 4

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Table 2. Selected House and Occupancy Characteristics1 1 Parameter HENGH CNHS
Year Built2 2011-2017 2002-2005
Monitoring 07/2016–04/2018 08/2006–03/2007
Age at Testing3
91% 3 years 90% 4.3 years
Floor Area (m2)
4 Mean
Median (10th–90th)
244
243 (146–339)
248
251 (160–339)
Density (m2/person)
Mean
Median (10th-90th)
88 77 (45–143)
90 80 (48–142)
Gas Cooking Burners
Cooktop / Oven 100% / 43% 2% / 27%
1Additional information in SI Tables S5-S15.2Table S5. 3Table S6. 4Table S7. 25Others had electric cooking. 3 Table 3. Time-averaged pollutant concentrations in California homes built 2011-2017 (HENGH, 4 current study) and 2002-2005 (CNHS, Offermann, 2009).

Location HCHO (ppb) PM2.5 g/m3
) NO2 (ppb) CO2 (ppm)
Statistic HENGH CNHS1 HENGH CNHS1 HENGH CNHS1 HENGH CNHS2 Indoor N=68 N=105 N=67 N=28 N=66 N=29 N=69 N=107
Mean 19.8 35.0 7.5 13.4 5.8 5.2 620 610
Median 18.2 29.3 4.8 10.5 4.5 1.6 608 564
10th–90th 13–28 11–70 1.6–16 6.0–31 1.1–12 1.4–12 481–770 405–890 Outdoor N=66 N=39
4 N=673 N=114 N=65 N=114 No data No data
Mean 2.2 1.8 9.3, 10.5 7.9 5.4 2.1
Median 2.3 1.7 6.8, 9.7 8.7 3.6 1.5
10th–90th 1.4–3.1 0.6–2.8

2.7–18.1,

5.3–16.7

5.0–10 0.1–11 1.4–1.7
1 From CNHS “all-home” sample frame dataset. 2 From Table 39 of Offermann (2009). 3 5 The first set of outdoor 6 values are from unadjusted, on-site photometer measurements over the full monitoring period at each home; the 7 second set are from air quality monitoring stations nearby to the homes and use only the 24-h data from complete days during each monitoring period.
4 8 The CNHS collected one outdoor sample per cluster of 2-3 homes in close 9 proximity. Outdoor formaldehyde collected at clusters for all 108 homes. Outdoor samples for PM2.5 and NO2 10 collected for clusters that included 28 homes total.

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1 Table 4. Discomfort rates reported by participants in California homes built with code-required 2 mechanical ventilation (HENGH), recent online survey of homes mostly built before dwelling unit 3 ventilation was required, and field study of homes built before ventilation was required (CNHS).

Parameter HENGH field
study (n=68)1
HENGH online
survey (n=2271)
1 CNHS2
Too hot Winter: 14%
Summer: 31%
Winter: 10%
Summer: 41%
19%
Too cold Winter: 29%
Summer: 4%
Winter: 20%
Summer: 9%
15%
Too dry 9% 11% 8%
Too damp (HENGH) / too humid
(CNHS)
1% 2% 2%
Too much air movement
(HENGH) / too drafty (CNHS)
1% 5% 0%
Too stagnant / not enough air
movement
21% 18% 12%
Too dusty Not asked Not asked 11%
Musty odor 1% 3% 13% in bathroom
1-3% other locations
1 When asked how often does the discomfort occurs, respondent selected “few times per week” or “daily”. 2 4 From 5 Table 44 of Offermann (2009), respondents reporting that the discomfort occurred during 3 weeks prior. For musty 6 odor, the CNHS asked if participants had “observed, seen or smelled mold” in the past week in various locations. 7

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1 2 Figure 1. Locations of study homes.
3

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 32
1 2 Figure 2: One-week integrated formaldehyde measured with passive samples: Comparison of 3 concentrations in master bedroom and large, open common room (main) indoor locations 4 5 Figure 3: Time-Integrated formaldehyde concentrations measured in California homes built before 6 (CNHS) and after (HENGH) mechanical ventilation was required.

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1 2 Figure 4: Time-averaged PM2.5 concentrations measured in California homes built before (CNHS) 3 and after (HENGH) mechanical ventilation was required. 4 5 Figure 5: Time-integrated NO2 concentrations measured in California homes built before (CNHS) 6 and after (HENGH) mechanical ventilation was required. Most CNHS homes had electric cooking 7 and all HENGH homes had gas cooking burners.

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1 2 Figure 6: Time-average CO2 concentrations in indoor main living space and bedrooms. 3 4 Figure 7: Nighttime (midnight-5am) CO2 in indoor main living space and bedrooms 5

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1 5. References
2 1. Piazza T, Lee R, Sherman M, Price P. Study of Ventilation Practices and Household 3 Characteristics in New California Homes. Final Report for Energy Commission Contract 4 500-02-023 and ARB Contract 03-026. CEC-500-2007-033; Sacramento, CA: California 5 Energy Commission and California Air Resources Board; June 2007, 2007. 6 2. Offermann FJ. Ventilation and Indoor Air Quality in New Homes. CEC-500-2009-085; 7 Sacramento, CA: California Energy Commission and California Air Resources Board; 2009. 8 3. Lawrence Berkeley National Lab. LBNL. Ventilate Right: Ventilation Guide for New and 9 Existing California Homes. https://homes.lbl.gov/ventilate-right/ashrae-standard-622 Last 10 Accessed:05-Oct-2019-
11 4. Logue JM, Klepeis NE, Lobscheid AB, Singer BC. Pollutant Exposures from Natural Gas 12 Cooking Burners: A Simulation-Based Assessment for Southern California. Environ Health 13 Perspect. 2014;122:43-50.
14 5. Mullen NA, Li J, Russell ML, Spears M, Less BD, Singer BC. Results of the California 15 Healthy Homes Indoor Air Quality Study of 2011-2013: impact of natural gas appliances on 16 air pollutant concentrations. Indoor Air. 2016;26:231-45. 17 6. Chan WR, Kim Y-S, Less BD, Singer BC, Walker IS. Ventilation and Indoor Air Quality in 18 New California Homes with Gas Appliances and Mechanical Ventilation. LBNL-2001200; 19 Berkeley CA: Lawrence Berkeley National Laboratory; 2019. 20 7. California Air Resources Board. CARB. Composite Wood Products Airborne Toxic Control 21 Measure. www.arb.ca.gov/toxics/compwood/compwood.htm Last Accessed:05-Oct-2019- 22 8. Chan WR, Kim Y-S, Singer BC, Walker IS, Sherman MH. Healthy Efficient New Gas 23 Homes (HENGH) Field Study Protocol. LBNL-1005819; Berkeley, CA: Lawrence Berkeley 24 National Lab; 2016.
25 9. Walker IS, Wray CP, Dickerhoff DJ, Sherman MH. Evaluation of flow hood measurements 26 for residential register flows. LBNL-47382; Berkeley CA: Lawrence Berkeley National 27 Laboratory; 2001.
28 10. Dacunto PJ, Cheng KC, Acevedo-Bolton V, Jiang RT, Klepeis NE, Repace JL, Ott WR, 29 Hildemann LM. Real-time particle monitor calibration factors and PM2.5 emission factors 30 for multiple indoor sources. Environmental Science-Processes & Impacts. 2013;15:1511- 31 1519.
32 11. Tryner J, Good N, Wilson A, Clark ML, Peel JL, Volckens J. Variation in gravimetric 33 correction factors for nephelometer-derived estimates of personal exposure to PM2.5. 34 Environ Pollut. 2019;250:251-261.
35 12. Singer BC, Delp WW. Response of consumer and research grade indoor air quality monitors 36 to residential sources of fine particles. Indoor Air. 2018;28:624-639. 37 13. Zhang J, Marto JP, Schwab JJ. Exploring the applicability and limitations of selected optical 38 scattering instruments for PM mass measurement. Atmos. Meas. Tech. 2018;11:2995-3005. 39 14. Wang XL, Chancellor G, Evenstad J, Farnsworth JE, Hase A, Olson GM, Sreenath A, 40 Agarwal JK. A Novel Optical Instrument for Estimating Size Segregated Aerosol Mass 41 Concentration in Real Time. Aerosol Sci Technol. 2009;43:939-950. 42 15. Carter EM, Jackson MC, Katz LE, Speitel GE. A coupled sensor-spectrophotometric device 43 for continuous measurement of formaldehyde in indoor environments. J Exposure Sci 44 Environ Epidemiol. 2014;24:305-310.

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 36
1 16. Maruo YY, Yamada T, Nakamura J, Izumi K, Uchiyama M. Formaldehyde measurements in 2 residential indoor air using a developed sensor element in the Kanto area of Japan. Indoor 3 Air. 2010;20:486-493.
4 17. Offermann FJ, Hodgson AT. In Accurancy of Three Types of Formaldehyde Passive 5 Samplers, Indoor Air 2018, Philadelphia PA, 2018; International Society of Indoor Air 6 Quality Sciences: Philadelphia PA, 2018.
7 18. Matthews TG, Thompson CV, Wilson DL, Hawthorne AR, Mage D. Air velocities inside 8 domestic environments: An important parameter in the study of indoor air quality and 9 climate. Environ Int. 1989;15:545-550.
10 19. Chan WYR, Joh J, Sherman MH. Analysis of air leakage measurements of US houses. 11 Energ Buildings. 2013;66:616-625.
12 20. Salthammer T, Mentese S, Marutzky R. Formaldehyde in the Indoor Environment. Chem 13 Rev. 2010;110:2536-2572.
14 21. Allen RW, Adar SD, Avol E, Cohen M, Curl CL, Larson T, Liu LJS, Sheppard L, Kaufman 15 JD. Modeling the Residential Infiltration of Outdoor PM2.5 in the Multi-Ethnic Study of 16 Atherosclerosis and Air Pollution (MESA Air). Environ Health Perspect. 2012;120:824- 17 830.
18 22. Wallace LA, Mitchell H, O'Connor GT, Neas L, Lippmann M, Kattan M, Koenig J, Stout 19 JW, Vaughn BJ, Wallace D, Walter M, Adams K, Liu LJS. Particle concentrations in inner20 city homes of children with asthma: The effect of smoking, cooking, and outdoor pollution. 21 Environ Health Perspect. 2003;111:1265-1272.
22 23. Allen R, Larson T, Sheppard L, Wallace L, Liu LJS. Use of real-time light scattering data to 23 estimate the contribution of infiltrated and indoor-generated particles to indoor air. Environ 24 Sci Technol. 2003;37:3484-3492.
25 24. Meng QY, Spector D, Colome S, Turpin B. Determinants of indoor and personal exposure 26 to PM2.5 of indoor and outdoor origin during the RIOPA study. Atmos Environ. 27 2009;43:5750-5758.
28 25. Rodes CE, Lawless PA, Thornburg JW, Williams RW, Croghan CW. DEARS particulate 29 matter relationships for personal, indoor, outdoor, and central site settings for a general 30 population. Atmos Environ. 2010;44:1386-1399.
31 26. Mishra AK, van Ruitenbeek AM, Loomans M, Kort HSM. Window/door opening-mediated 32 bedroom ventilation and its impact on sleep quality of healthy, young adults. Indoor Air. 33 2018;28:339-351.
34 27. Strom-Tejsen P, Zukowska D, Wargocki P, Wyon DP. The effects of bedroom air quality on 35 sleep and next-day performance. Indoor Air. 2016;26:679-686. 36 28. Wallner P, Munoz U, Tappler P, Wanka A, Kundi M, Shelton JF, Hutter HP. Indoor 37 Environmental Quality in Mechanically Ventilated, Energy-Efficient Buildings vs. 38 Conventional Buildings. Int J Environ Res Public Health. 2015;12:14132-14147. 39 29. Wallner P, Tappler P, Munoz U, Damberger B, Wanka A, Kundi M, Hutter HP. Health and 40 Wellbeing of Occupants in Highly Energy Efficient Buildings: A Field Study. Int J Environ 41 Res Public Health. 2017;14.
42 30. Lajoie P, Aubin D, Gingras V, Daigneault P, Ducharme F, Gauvin D, Fugler D, Leclerc JM, 43 Won D, Courteau M, Gingras S, Heroux ME, Yang W, Schleibinger H. The IVAIRE project 44 - a randomized controlled study of the impact of ventilation on indoor air quality and the 45 respiratory symptoms of asthmatic children in single family homes. Indoor Air. 46 2015;25:582-597.

IAQ in Mechanically Ventilated U.S. Homes INA-190-10-297-R2 04-April-2020 37
1 31. Balvers J, Bogers R, Jongeneel R, van Kamp I, Boerstra A, van Dijken F. Mechanical 2 ventilation in recently built Dutch homes: technical shortcomings, possibilities for 3 improvement, perceived indoor environment and health effects. Architectural Science 4 Review. 2012;55:4-14.
5 32. Laverge J, Delghust M, Janssens A. Carbon Dioxide Concentrations and Humidity Levels 6 Measured in Belgian Standard and Low Energy Dwellings with Common Ventilation 7 Strategies. International Journal of Ventilation. 2015;14:165-180. 8 33. Eklund K, Kunkle R, Banks A, Hales D. Pacific Northwest Residential Effectiveness Study - 9 FINAL REPORT NEEA Report #E15-015; Portland, OR: Prepared by Washington State 10 University Energy Program; 2015.
11 34. Sonne JK, Withers C, Vieira RK. Investigation of the effectiveness and failure rates of 12 whole-house mechanical ventilation systems in Florida. FSEC-CR-2002-15; Cocoa, FL:
13 June 1, 2015, 2015.
14 35. Hult EL, Willem H, Price PN, Hotchi T, Russell ML, Singer BC. Formaldehyde and 15 acetaldehyde exposure mitigation in US residences: in-home measurements of ventilation 16 control and source control. Indoor Air. 2015;25:523-535. 17 36. Frey SE, Destaillats H, Cohn S, Ahrentzen S, Fraser MP. The effects of an energy efficiency 18 retrofit on indoor air quality. Indoor Air. 2015;25:210-219. 19 37. Huangfu YB, Lima NM, O'Keeffe PT, Kirk WM, Lamb BK, Pressley SN, Lin BY, Cook 20 DJ, Walden V, Jobson BT. Diel variation of formaldehyde levels and other VOCs in homes 21 driven by temperature dependent infiltration and emission rates. Build Environ. 2019;159. 22 38. Singer BC, Hodgson AT, Hotchi T, Kim JJ. Passive measurement of nitrogen oxides to 23 assess traffic-related pollutant exposure for the East Bay Children's Respiratory Health 24 Study. Atmos Environ. 2004;38:393-403.
25

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-1

SUPPORTING INFORMATION
Indoor Air Quality in California Homes with Code-Required Mechanical Ventilation Brett C. Singer1, Wanyu R. Chan1, Yang-Seon Kim1,2, Francis J. Offermann3, Iain S. Walker1 1 Residential Buildings Systems Group and Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
2 Wichita State University, Wichita, Kansas, USA
3 Indoor Environmental Engineering, San Francisco California, USA Contents
CONTENTS ......................................................................................................................................................... 1 LIST OF FIGURES................................................................................................................................................. 2 LIST OF TABLES................................................................................................................................................... 2 METHODS .......................................................................................................................................................... 4 RECRUITMENT AND SCREENING ........................................................................................................................................4 INFORMATION COLLECTED FOR HOUSE AND EQUIPMENT CHARACTERIZATION............................................................................4 SPECIFICATION OF AIR QUALITY MONITORING EQUIPMENT....................................................................................................5 LOCATIONS OF AMBIENT AIR QUALITY MONITORING STATIONS USED TO ESTIMATE OUTDOOR PM2.5 ...........................................8 QUALITY ASSURANCE PROCEDURES FOR AIR QUALITY MONITORS ...........................................................................................9 WEIGHING OF FILTERS FOR GRAVIMETRIC PM2.5 DETERMINATION........................................................................................10 PASSIVE SAMPLER PROCEDURES AND QUALITY ASSURANCE .................................................................................................10 POTENTIAL IMPACT OF LOW AIR SPEEDS ON PASSIVE SAMPLER DATA ....................................................................................12 ADJUSTMENTS TO FORMALDEHYDE DATA FROM FM-801 MONITOR.....................................................................................13 CALCULATION OF OUTDOOR AIR EXCHANGE RATE..............................................................................................................13 ESTIMATE OF POTENTIAL BIAS IN CALCULATED AIR INFILTRATION..........................................................................................14 RESULTS............................................................................................................................................................16 HOUSE CHARACTERISTICS ..............................................................................................................................................16 HOUSEHOLD DEMOGRAPHICS.........................................................................................................................................19 AIR TIGHTNESS ............................................................................................................................................................21 VENTILATION AND FILTRATION EQUIPMENT ......................................................................................................................22 GENERAL OCCUPANCY AND SOURCES – FROM SURVEY .......................................................................................................27 OCCUPANCY AND SOURCES DURING WEEK OF MONITORING ...............................................................................................27 AIR POLLUTANT CONCENTRATIONS: FORMALDEHYDE..........................................................................................................30 AIR POLLUTANT CONCENTRATIONS: PM2.5 .......................................................................................................................31 ANALYSIS OF REGULATORY AIR MONITORING DATA TO ESTIMATE PM2.5 OUTSIDE OF HENGH HOMES.......................................31 AIR POLLUTANT CONCENTRATIONS: NITROGEN DIOXIDE AND NITRIC OXIDE............................................................................34 AIR POLLUTANT CONCENTRATIONS: CO2..........................................................................................................................35 IEQ SATISFACTION BY VENTILATION SYSTEM OPERATION ....................................................................................................36 RECRUITMENT POSTCARD.................................................................................................................................38 DAILY ACTIVITY LOG..........................................................................................................................................39 OCCUPANT SURVEY...........................................................................................................................................40

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List of Figures
Figure S1: Locations of PM2.5 air monitoring stations (blue) in relation to study homes (red).... 8 Figure S2. Results of side-by-side deployment of indoor and outdoor MetOne photometers at each house, typically outdoors........................................................................................................ 9 Figure S3: Distribution of ACH50 from Envelope Leakage Measurements................................ 21 Figure S4: Bathroom Exhaust Fan Measured Flow Rates............................................................ 23 Figure S5: Total Estimated Air Exchange Rate............................................................................ 25 Figure S6: Infiltration and Total Airflow (Mechanical + Infiltration).......................................... 26 Figure S7. Comparison between mean outdoor PM2.5 measured using MetOne photometer and inverse distance weighted ambient monitoring data (N=67). ....................................................... 33 Figure S8: One-Week Integrated NO2, NO, and NOx Concentrations........................................ 34 Figure S9: Overnight (midnight-5am) CO2 measurements in indoor main living space and master bedroom. ....................................................................................................................................... 35 List of Tables
Table S1. Specifications of air pollutant monitoring equipment .................................................... 5 Table S2. Comparison of study design and measurement methods HENGH and CNHS studies of indoor air quality and ventilation in single family detached homes............................................... 6 Table S3. Sampled Homes by Cities and Climate Zones (N=70) ................................................ 16 Table S4. Sampled Homes by Seasons......................................................................................... 16 Table S5. Sampled Homes by Year Built ..................................................................................... 17 Table S6. Age of Homes When Sampled1.................................................................................... 17 Table S7: Sampled Homes by Floor Area .................................................................................... 17 Table S8: Sampled Homes by Number of Stories........................................................................ 18 Table S9: Sampled Homes by Number of Bedrooms................................................................... 18 Table S10: Sampled Homes by Number of Bathrooms................................................................ 18 Table S11: Locations of Gas Fireplaces ....................................................................................... 19 Table S12: Number of Occupants in Sampled Homes ................................................................. 19 Table S13: Number of Occupants in Sampled Homes by Age Group ......................................... 20 Table S14: Total Household Income in Sampled Homes............................................................. 20 Table S15: Education Level of Head of Household in Sampled Homes...................................... 21 Table S16: Whole House Ventilation System Type ..................................................................... 22 Table S17: Whole House Ventilation System Control ................................................................. 22 Table S18: Air Filter MERV Ratings ........................................................................................... 23 Table S19: Time Since Last Air Filter Change............................................................................. 24 Table S20: Condition of Air Filters Observed by Field Team...................................................... 24 Table S21: How Frequently Are Candles Used in the Home ....................................................... 27 Table S22: Number of Furry Pets in Homes................................................................................. 27 Table S23: Self-Reported Average Occupancy (Number of People) When Home Was Occupied ....................................................................................................................................................... 27 Table S24: Self-Reported Average Occupied Hours per Day During Monitoring Week ............ 28

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Table S25: Self-Reported Cooktop Use (Number of Times) During Monitoring Week.............. 28 Table S26: Self-Reported Oven and Outdoor Grill Use During Monitoring Week ..................... 28 Table S27: Average Cooking Activity Duration During One-Week Monitoring, Self-Reported 29 Table S28. CNHS Activities (Table 42 and 43 of Offermann et al. 2009):.................................. 29 Table S29: Comparison of Time-Integrated Formaldehyde Measured with Two Methods......... 30 Table S30. Time-integrated PM2.5 concentrations measured by MetOne and Thermo pDR-1500 photometers compared with gravimetric analysis of co-located filter samples............................ 31 Table S31. Summary statistics (N=67) of the mean outdoor PM2.5 measured using MetOne photometer and inverse distance weighted ambient monitoring data........................................... 32 Table 32. Air quality satisfaction reported by participants........................................................... 36 Table 33. Satisfaction with seasonal temperature conditions by ventilation system status on first visit to home.................................................................................................................................. 36 Table 34. Satisfaction with environmental parameters by ventilation system status on first visit to home.............................................................................................................................................. 37

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Methods
Recruitment and Screening
Most participants were recruited through postcards mailed to addresses identified on a real estate website (Zillow.com), targeting single-family, detached homes built 2011 or later. Some participants learned of the study via referrals. LBNL attempted to contact all who expressed interest through the study website or by telephone. On contact, participant eligibility was confirmed and participant responsibilities, including keeping windows closed, were described.

This process identified 103 eligible and interested candidates and led to monitoring in 72 homes.

Most of the other 31 candidates did not respond to three attempts to schedule visits or withdrew before the first scheduled visit. One consented participant withdrew between the first and second visits. Another was excluded when the field team found during the first visit that the home was built before 2011. These participants received a $75 gift card. Two monitored homes did not have compliant ventilation systems and are not included in the data reported herein.

Information Collected for House and Equipment Characterization  House information: floor area and ceiling heights; number of stories, bedrooms, full and half baths, and other rooms on each floor; attached garage, number of parking spots, etc.  Whole-house mechanical ventilation system. Noted basic design (exhaust, supply, or balanced); type of control; make, model and rated flow; and fan settings.  Other ventilation equipment: bath and toilet room exhaust fans, kitchen range hood, and any laundry exhaust fans. Noted make, model and rated flow, type of control for each fan; and for kitchen note if range hood is microwave or simple range hood.  Heating and cooling system(s). Noted type of system (all were forced air), make and model, capacity (in tons and Btuh) and whether system was zoned. Noted dimensions and location of each return and locations of filter(s) if not at the return air grille. Noted location(s) and types of thermostats. For each filter in a forced air heating or cooling system, recorded make, model and performance rating and visually assessed condition of filter; also took photo.

Identified and characterized thermostat and marked location on floor plan.  Attic. Noted whether it was vented or unvented and the type of insulation. Photographed ductwork, gas furnace, exhaust fans, and vents.
 Gas-burning appliances. Noted make, model and firing rates of all burners or photographed nameplate. Noted locations on floor plans.

Floor plans were generally obtained from builders’ websites; otherwise they were sketched on site. Photos were taken of the home exterior, garage, gas appliances, mechanical ventilation equipment, air filters, and any special features.

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Specification of Air Quality Monitoring Equipment
Table S1. Specifications of air pollutant monitoring equipment Parameter Device make and
model
Range and
Resolution
Accuracy in
Product Literature
Other
Temperature Onset HOBO
UX100-011
Range: -20° to 70°C.

Resolution: 0.024°C at
25°C
±0.21°C from 0° to
50°C
Response time: 4 min in
air moving 1 m/s
Drift: <0.1°C per year
Temperature Extech SD800 0 to 50°C ±0.8°C
Relative
humidity
Onset HOBO
UX100-011
Range: 1% to 95%
(non-condensing);
Resolution: 0.05%
±2.5% from 10% to
90%; up to ±3.5% at
25°C including
hysteresis
Response time: 11 sec to
90% in airflow of 1 m/s
Drift: <1% per year
typical
Relative
humidity
Extech SD800 Range: 10-90% ±4%RH below
70%; 4% of reading
+ 1% for 70–90%
range
Particulate
matter, PM2.5
MetOne ES-642
MetOne BT-645
Range: 0-100 mg/m3.

Resolution: 0.001
mg/m3.
± 5% traceable
standard with 0.6um
PSL
Carbon dioxide,
CO2
Extech SD800 Range: 0-4000 ppm;
Resolution: 1 ppm
±40 ppm under
1000 ppm; ±5%
>1000 ppma
Nitrogen
Dioxide
Aeroqual 500
Series
Range: 0 to 1 ppm ± 0.02 ppm within 0
to 0.2 ppm range
Formaldehyde GrayWolf
(Shinyei)
Multimode
Monitor
20 to 1000 ppb ± 4ppb for <40ppb,
± 10% of reading
for ≥40ppb
30 min resolution; 20
ppb is lowest reliable
value with stated
accuracy
a Extech monitors did not achieve this performance when compared to a calibrated PPSystems EGM-4 in an injection-decay experiment in a small, room-sized chamber during monitoring as described in the text.

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Table S2. Comparison of study design and measurement methods HENGH and CNHS studies of indoor air quality and ventilation in single family detached homes Parameter HENGH CNHS
Number of Homes 70 108
Year Built
(Monitoring)
2011-2017
(Jul 2016 – Apr 2018)
2002-2005
(Aug 2006 – March 2007)
Dwelling Unit
Mechanical
Ventilation
(Operational
Systems)
All 70 homes had systems that met
2008 or later California code:
64 exhaust; 6 supply.
13 homes had systems that met
ASHRAE 62.2-2004:
8 balanced (HRV); 5 with duct
connecting FAU to outdoors and
controller for ventilation.
9 homes had duct connecting FAU
to outdoors but no controller for
ventilation.

Gas Cooking
Appliances
Cooktops: 100%
Ovens 43%
Cooktops: 2%
Ovens: 27%
Natural
Ventilation
Occupants agreed to not use
windows for ventilation.

Occupants asked to use windows
as they do normally.

Duration ~7 days ~24 hour
Locations for IAQ
parameter
measurements
• Living, dining or family room:

PM2.5, CO2, NOX, NO2,
formaldehyde.
• Master bedroom: CO2 and
formaldehyde.
• Other bedroom(s): CO2
• Outside: PM2.5, NOX, NO2,
formaldehyde.
• Living, dining or family room:

VOCs, CO2, CO, formaldehyde in
all homes; PM2.5 in 28 homes; NO2
in 29 homes.
• Outside: formaldehyde at each
cluster of 2-3 homes (n=39); PM2.5
and NO2 at 11 clusters.

Air Contaminant
Measurement
Methods
• Formaldehyde, NO2, NOX: timeintegrated passive samplers. • Formaldehyde: colorimetric
sensor/photometer, 30-min logs
• PM2.5: Estimated by photometry
with indoor adjusted using timeintegrated filter samples. • CO2: Passive, NDIR, 1-min
• Formaldehyde, NO2, 10 VOCs:
time-integrated, pumped samples
• PM2.5: time-integrated pumped
filter samples with size selective
inlets and gravimetric analyses.
• CO2: Passive, NDIR, 1-min
• CO: Passive, Electrochemical, 1-
min

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Parameter HENGH CNHS
• T: thermistor sensor
• RH: Thin film capacitive sensor
• T: thermistor sensor
• RH: Thin film capacitive sensor
Air Contaminant
Measurement
QA/QC
• Formaldehyde, NOX, NO2:
duplicates, field blanks,
manufacturer’s recommended
sampling rate.
• PM2.5: zero at sample start, span
adjustment calculated from
simultaneous gravimetric samples
at 8 indoor locations.
• CO2: baseline and span checks at
middle of study. No adjustment of
field data.
• NO2: baseline and span checks
prior to sampling in most homes.
• T and RH sensors used factory
calibration with no field
calibrations.
• Formaldehyde, PM2.5, NO2, 10
VOCs: duplicates, field blanks,
sampling rate measurements at
start and stop.
• CO2 and CO: zero and span
calibration at start and stop of
sampling at each home and
corresponding adjustment of field
data.
• T and RH sensor calibration prior
to field session and corresponding
adjustment of field data.

Record of natural
ventilation use.

Participant affirmed that windows
would not be used for ventilation,
per study requirements. Loggers on
two most-used doors. No loggers
or signage on windows. Daily log
asked for hours that any windows
were opened but not the amount
opened.

Occupants instructed to operate
windows normally. Loggers on
windows that occupants reported to
use most frequently, and signage
with logs on all windows for
occupants to record hours and
amount opened.

Method to
measure or
estimate outdoor
air ventilation rate
Estimated from measured
mechanical airflows and modeled
infiltration with unbalanced
ventilation.

Measured with perfluorocarbon
tracer (PFT) gas.

Abbreviations: HRV = Heat recovery ventilator; FAU = forced air unit; NDIR = non-disperse infrared.

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Locations of Ambient Air Quality Monitoring Stations Used to Estimate Outdoor PM2.5  San Francisco Bay Area
 Sacramento and Central Valley
Southern California 
Figure S1: Locations of PM2.5 air monitoring stations (blue) in relation to study homes (red).

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Quality Assurance Procedures for Air Quality Monitors
The indoor and outdoor PM2.5 monitors were co-located for roughly one hour during the instrument deployment visit at each home. In most cases the co-location was outdoors at the location of the outdoor monitor. Co-located comparisons were available from 45 homes. In two of the homes, the two monitors measured very different concentrations likely because the outdoor monitor had a heated inlet that was set to activate when relative humidity reached above 60%, and the indoor monitor did not. The heated inlet prevents condensation that could damage the instrument. The indoor monitor did not have a heated inlet because high humidity is generally not a concern when sampling indoors. At the two homes during the one-hour colocation test, the outdoor monitor measured high concentration of PM2.5 (51 and 60 g/m3 at
Home 063 and 068, respectively). Without the heated inlet, the co-located indoor monitor measured 111 and 78 g/m3, respectively. The two homes were sampled in winter (January 2018) in Tracy and Manteca CA, where high humidity condition in the morning likely explained this difference between the co-located indoor and outdoor PM2.5 monitors. Excluding these two cases, the co-located indoor and outdoor PM2.5 monitors agreed to within 1.9 g/m3 on average (median = 0.9 g/m3), with the outdoor monitor reporting lower concentrations than the indoor monitor in 79% of the indoor side-by-side deployments. This is likely because the heated inlet intended to prevent condensation resulted in some volatilization of organics in the outdoor particles. The results of the brief side-by-side deployment of indoor and outdoor MetOne photometers at each home are provided in Figure S2.

Figure S2. Results of side-by-side deployment of indoor and outdoor MetOne photometers at each house, typically outdoors.

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The Extech CO2 monitors were co-located for 1 hour at each home or at a warehouse where the field team prepared equipment before a visit. The field team confirmed that CO2 monitors agreed with one another to within a range of 100 ppm. Extech monitors were also calibrated at LBNL during two breaks in sampling, with 5 units checked during Feb 2017 and 7 units (including two from first round) checked during Dec 2017. On each occasion, the monitors were set up in a well-mixed room along with an EGM-4 gas analyzer (PP systems, Amesbury, MA, USA). The EGM-4 was separately calibrated using standard gas of known CO2 concentrations between 0 and 2500 ppm. During each event, CO2 concentrations in the chamber were raised by injection of pure CO2 then left to decay with air exchange. Hourly concentrations were calculated for each monitor. The first-hour means were 1056 and 1537 ppm for the two events. Decay periods were 26 and 7 hours to final-hour concentrations of 420 and 529 ppm. Hourly average concentrations reported by the Extech units differed (high to low range) by 71–86 ppm during the first spikedecay and 111–168 ppm during the second. Averaged over the full spike-decay intervals, differences between Extech units and the EGM-4 ranged from -20 ppm to 84 ppm.

The Aeroqual 500 NO2 monitor was calibrated before each visit with zero gas and a 1 ppm NO2 standard gas. Monitor response was adjusted to match those values following manufacturer instructions. Despite this calibration step, there was generally a substantial, positive offset in the time-integrated NO2 concentration measured by the Aeroqual when compared with the concentrations measured using the passive sampler. Further processing of the Aeroqual NO2 data is required, which is beyond the scope of this paper.

Weighing of Filters for Gravimetric PM2.5 Determination Gravimetric samples were collected on 37 mm diameter, 2.0 micron pore size, Pall Teflo filters with ring. Prior to deployment, filters were preconditioned for 24 hours at controlled temperature and humidity conditions (47.5 +/- 1.5 % RH and 19.5±0.5 ºC), passed over a deionizing source to remove static charge and weighed twice using a Sartorius SE2-F balance. Pre-weighed filters were loaded into the pDR-1500 photometers and were shipped to GTI for deployment. After a week of monitoring, GTI shipped the pDR monitors back to LBNL. LBNL removed the filters, and repeated the preconditioning and weighing procedures. The collected mass was determined as the post-sampling versus pre-sampling mass difference. The field blank was subtracted from the sample mass. Sampled air volume was taken from the pDR. Mass concentration was calculated as collected PM mass / sample air volume. The sample flow rate of the pDR was checked in the lab before and after each field use.

Passive Sampler Procedures and Quality Assurance
Ogawa samplers were prepared according to manufacturer protocols. Prior to assembly for field deployment, all parts of the samplers were washed thoroughly with deionized water and allowed to dry thoroughly in a laboratory at LBNL. Sample pads were stored in the refrigerator in their original packaging until they were inserted into samplers. After samplers were assembled with new sample pads, they were placed in sealed amber plastic bags (Ziploc) and shipped to the field team in an insulated box with ice packs to keep them cool.

All passive samplers were shipped to LBNL for analysis. To avoid damage to the chemical samplers from extreme temperatures, samplers were mailed in an insulated shipping container

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with ice packs to keep them cool. The samples were extracted and analyzed following the protocols provided by each company (Ogawa & Company 2017; SKC, Inc. 2017). All Ogawa samples were extracted for analysis within 30 days from when the samplers were assembled.

For each NOX and NO2 sample we subtracted the mass determined from the field blank at the same home before calculating the sample period concentrations of NOX, NO2 and NO as the difference between the adjusted NOX and NO2 concentrations. For two homes that did not have a field blank, we subtracted 0.15 micrograms for NO2 and 0.22 micrograms for NOx, which are the mean mass determined from all available field blanks; these masses correspond to 0.9 ppb of NO2 and 1.3 ppb of NOx for a 7-day collection period. Following blank subtraction, 4 indoor and 5 outdoor NO2 samples and 1 indoor and 6 outdoor NOx samples had negative concentrations; the occurrence of negative values results from variability in the blank correction and low sample masses. These negative NO2 and NOx concentrations were retained when calculating summary statistics. Analysis of 64-paired duplicates of indoor samples found that agreement in NO2 concentrations was within 0.6 ppb on average (median = 0.3 ppb). When available, duplicates were averaged to provide a better estimate of the indoor concentrations of NO, NO2, and NOx.

Sampling rates were calculated using co-located temperature and relative humidity measurements following manufacturer instructions.

The formaldehyde concentration determined by passive sampler at each home also was adjusted by the effective sample period concentration determined from the field blank at the same home.

For the eleven homes that did not have a formaldehyde passive sample field blank, we subtracted

0.15 micrograms, which is the mean mass determined from all available field blanks (and corresponds to 0.6 ppb for a 7-day collection period). Sixty-six paired indoor formaldehyde samples agreed to within 1.0 ppb on average (median = 0.7 ppb). When available, duplicates were averaged to provide a better estimate of the indoor concentrations. A sampling rate of 20.4 ml/min were used following manufacturer instructions.

The UMEx contains an internal blank within each sampler that can potentially be used for convenience instead of deploying a separate field blank sampler. However, analysis of the internal blank suggested that even though it was not directly exposed to the sampling air, some formaldehyde was collected, possibly because the compartment isolating the internal blank was not completely airtight. The average analyte mass determined from internal blanks of indoor samples was 0.6 micrograms; this is 4 times the field blank value noted above.

Formaldehyde indoor emission rates E (g/m3-h) were calculated using a simple mass-balance equation assuming well-mixed, steady state condition. The same method was applied by Offermann (2009) to estimate indoor emission rates of formaldehyde and other VOCs.

E = (Ci – Co)AER (1)
Outdoor formaldehyde concentration (Co, g/m3) was subtracted from the indoor concentration (Ci, g/m3) measured at the central location, assuming that there is no loss in formaldehyde as the outdoor air enters through the building envelope. Air exchange rate (AER, 1/h) is assumed to be the only mechanism that removals formaldehyde from the indoor air. Air exchange rate was estimated from natural infiltration airflow and mechanical airflow using sub-additivity, as described later in the Methods.

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-12
Potential Impact of Low Air Speeds on Passive Sampler Data The sampling rates of passive samplers may be impacted by low air speeds at the sampler inlet, as discussed by Offermann and Hodgson (2018)1and papers cited therein. At very low air speeds, diffusive uptake to the passive sampler causes a reduction in analyte concentration at the face of the air sampler relative to the surrounding indoor air, resulting in an effective increase in the diffusive path length and lower sampling rate.

Since air speeds were not measured in HENGH homes, we rely on the data of Mathews et.al. (1989)2to assess the potential for low air speeds to bias the passive sampler measurements in residences. Matthews et al. used a TSI Model 1620 omnidirectional anemometer to measure air speeds during daytime hours in various rooms of six occupied homes and in an unoccupied research house. The overall median air speed measured in the six occupied homes was 318 cm/min. HVAC operation was found to substantially impact air speeds, by a factor of 5 in one house and by roughly a factor of 2 in two other occupied houses. The median measured air speeds with HVAC off in three occupied homes and the research house were 90, 198, 342, and 246 cm/min. Among the rooms studied, air speeds were lowest in the master bedroom, with median values during no HVAC use of 108 cm/min across the three occupied houses. The condition with the lowest measured air speeds was in a bedroom that was completely unoccupied; during HVAC off times median air speeds were 66 cm/min. HVAC operation was not tracked in HENGH; but the median HVAC run time was 1.1 h per 24 h in the CNHS.

Using a TSI Model 8475 omnidirectional anemometer, Offermann and Hodson reported an air speed of 27 cm/min in an unoccupied office overnight with no HVAC operation.

Using the data above as reference points, Offermann provided the following correction factors for the geometries of the UMEx and Ogawa samplers at selected air speeds.

Air Speed (cm/min) UMEx CF Ogawa CF
27 1.21 1.16
66 1.09 1.07
100 1.06 1.04
300 1.02 1.01
Using the daytime airspeeds measured with no HVAC operation and assuming that condition applied roughly half the time in HENGH master bedrooms, and also assuming higher airspeeds with occupancy during nighttime hours, the bias from low air speeds would be on the order of 3% for formaldehyde and 2% for NOX and NO2. A bedroom that is completely unoccupied during the daytime and similar to the one reported in Matthews could have a bias of 4-5% for formaldehyde and 3-4% for NOX and NO2. If any rooms commonly experienced conditions similar to those observed overnight in the Offermann office, the bias would be 8-10%.

1 Offermann, F. J. and A. T. Hodgson (2018). Accurancy of Three Types of Formaldehyde Passive Samplers. Indoor Air 2018, Philadelphia PA, International Society of Indoor Air Quality Sciences. 2 Matthews, T. G., C. V. Thompson, D. L. Wilson, A. R. Hawthorne and D. Mage (1989). "Air velocities inside domestic environments: An important parameter in the study of indoor air quality and climate." Environment International 15: 545-550.

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Adjustments to Formaldehyde Data from FM-801 Monitor
Output of the FM-801 formaldehyde monitor dropped precipitously during events of substantial gas cooking burner use, presumably owing to an NO2 interference as described by Maruo et al.3 FM-801data that were clearly affected by cooking were identified by visual review, considering data from the time-resolved NO2 monitor and the cooktop and oven temperature sensors, and removed. Data marked as “<LOD” because they were below the 10 ppb quantitation limit were assigned a value of 7.3 ppb based on analysis of data from homes with the modified FM801software that provided numerical results below 10 ppb.

Calculation of Outdoor Air Exchange Rate
First, mechanical fan flows were calculated by summing exhaust fan flows (whole house exhaust fan, and other fans in bathroom, range hood, clothes dryer) weighted by their average usage time.

Since it was not practical to directly measure the airflow of the clothes dryers in most homes, we assumed dryer airflow of 125 cfm based on a recent report4.

Airflows from mechanical fans were added to calculate balanced (Qbalance_mech) and unbalanced (Q unbalance_mech) airflows by comparing minute by minute the amount of exhaust and supply air from usage data collected from each home. Next, air infiltration (Qinfiltration) was calculated using the flow coefficients and pressure exponents from average of pressurization and depressurization tests of building envelope leakage, determined as part of the DeltaQ Test, and using stack and wind coefficients following the ASHRAE Fundamentals Enhanced Model. Wind data were obtained from the nearest weather station5. Indoor and outdoor temperatures were monitored onsite. Photos of the house and surroundings were reviewed to determine the appropriate shelter class: either 4 (urban building on larger lots where sheltering obstacles are more than one building height away) or 5 (shelter produced by buildings or other structures that are closer than one house height away). The total ventilation rate was calculated following Equation 2, which uses a superposition adjustment (∅) to account for the sub-additivity of unbalanced mechanical airflows with air infiltration.

𝑄𝑡𝑜𝑡𝑎𝑙 = 𝑄𝑏𝑎𝑙𝑎𝑛𝑐𝑒_𝑚𝑒𝑐ℎ + 𝑄𝑢𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒_𝑚𝑒𝑐ℎ + ∅𝑄𝑖𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑖𝑡𝑜𝑛 (1) ∅=
Qinfiltration
Qunbalance_mech+Qinfiltration
(2)
Field teams measured ceiling heights in the great room, kitchen, living room, dining room, bedrooms, and other parts of the house. Air exchange rate was computed using an approximate house-averaged ceiling height and floor area recorded by the field team.

3 Maruo, Y. Y., T. Yamada, J. Nakamura, K. Izumi and M. Uchiyama (2010). "Formaldehyde measurements in residential indoor air using a developed sensor element in the Kanto area of Japan." Indoor Air 20(6): 486-493. 1 ENERGY STAR reports rated fan flow of clothes dryer typically range between 100 and 150 cfm. https://www.energystar.gov/sites/default/files/asset/document/ENERGY_STAR_Scoping_Report_Residential_Clot hes_Dryers.pdf
5 Data obtained from www.wunderground.com. During periods when wind was reported as “calm”, 1 mph (mile per hour) was assumed for calculating air infiltration rate.

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Estimate of Potential Bias in Calculated Air Infiltration While the ASHRAE Enhanced Model was developed from an extensive set of measured data and has been evaluated in several previous studies6,7,8, it is nevertheless valuable to consider that it could have varied performance in specific applications.

For this study, we used data from the CNHS – which measured time-integrated outdoor air ventilation rates using perfluorocarbon tracer gases (PFTs) – to evaluate the method used to calculate the infiltration portion of air exchange in HENGH, which measured mechanical airflows but calculated infiltration and overall AER.

The analysis looked at 13 CNHS homes that that had no window opening and no continuous mechanical ventilation (just occasional bathroom, kitchen, and clothes dryer exhausts); the overall AERs in these homes were thus dominated by infiltration. For these 13 homes, we calculated infiltration/air exchange in the same manner as was done for the HENGH study. (The only difference was that the calculation was done with 1-minute indoor temperature and intermittent exhaust fan data for HENGH and 15-minute data for CNHS. The calculations used the following parameters:
 default stack and wind coefficients for n=0.67;
 on-site data for indoor air temperature and local Meteorological Station data for outdoor air temperatures and wind speeds;
 setting all 0 mph wind speeds to 1 mph;
 using the interpolated ASHRAE Fundamentals Shelter Factors;  combining any intermittent mechanical airflow with infiltration using sub-additivity;  calculating the weekly integrated AER as the harmonic mean of 15-min estimates.

For each of the 13 CNHS homes, we compared the AER measured by PFT to the calculated AER to determine a correction factor, which we consider to be applicable to the calculated infiltration portion of AER. The median correction factor for the 13 homes was 1.81 with a range of 1.04 –

2.11. While this is high compared to published comparisons of measurements to infiltration model calculations, our hypothesis is that it is mostly due to the difficulty in selecting appropriate wind shelter factors.

Since most of the HENGH homes had continuous mechanical exhaust systems, infiltration accounted for only a fraction of the total outdoor air exchange. To assess the potential impact of infiltration bias calculated for the CNHS homes on the AERs calculated for HENGH homes, we

6 Walker, I.S. and Wilson, D.J., (1998), “Field Validation of Equations for Stack and Wind Driven Air Infiltration Calculations”, ASHRAE HVAC&R Research Journal, Vol. 4, No. 2, pp. 119-140. April 1998. ASHRAE, Atlanta, GA. LBNL 42361.
7 Francisco, P. and Palmiter, L. (1996). “Modeled and Measured Infiltration in Ten Single-Family Homes. Proc.

ACEEE 1996.
8 Wang, W., Beausoleil-Morrison, I. and Readon, J. 2008. Evaluation of the Alberta Air Infiltration Model Using Measurements and Inter-Model Comparisons. Building and Environment, 44. 309-318. doi:10.1016/j.buildenv.2008.03.005c

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adjusted the calculated infiltration rates for all HENGH homes by a factor of 1.81, then used subadditivity to combine the adjusted infiltration rates with the measured mechanical ventilation rates on a home-by-home basis. The median calculated adjustment factor for the total ventilation rates for HENGH homes is 1.18.

In addition to the potential bias from infiltration calculations, the calculated AERs for HENGH homes are also biased in some cases because the calculation assumed no window or door opening; any substantial use of windows or doors for ventilation would further raise AERs relative to calculated values.

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Results
House Characteristics
Table S3. Sampled Homes by Cities and Climate Zones (N=70) Gas
Utility
Service
Cal.

Climate
Zone
Cities (Number of Homes) Homes Total
PG&E 3 Discovery Bay (2), Hayward (2), Oakland (1) 5 48 11 Marysville (1) 1
12 Brentwood (12), El Dorado Hills (10), Elk Grove (6), Manteca (4), Mountain House (2), Pittsburg (2), Davis (1), Dublin (1), Sacramento (1)
39 13 Clovis (3) 3
SoCalGas
8 Irvine (2), Downey (1), Lake Forest (1), Yorba Linda (1) 5 9 Van Nuys (5), Alhambra (1) 6 22
10 Jurupa Valley (5), Chino (4), Corona (1), Eastvale (1) 11 Table S4. Sampled Homes by Seasons
Season Months Number of Homes
Winter Dec-Feb 16
Spring Mar-May 13
Summer Jun-Sep 27
Fall Oct-Nov 14
Total 70

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Table S5. Sampled Homes by Year Built
Year Built Number of Homes
2011 1
2012 7
2013 13
2014 17
2015 15
2016 14
2017 3
Total 70
Table S6. Age of Homes When Sampled1
HENGH Age When
Sampled (years)
HENGH Number of
Homes at Age
CNHS Percentile CNHS Age When
Sampled (years)
<1 2 Min 1.7
1 14 10th 2.4
2 32 25th 3.0
3 14 50th 3.4
4 4 75th 4.0
5 2 90th 4.3
No Response 2 Max 5.5
Total N=70 N=108
1 CNHS data from Table 15 of Offermann et al. (2009)
Table S7: Sampled Homes by Floor Area
Floor Area (ft2) Homes Floor Area (m2) Homes
<1500 5 <150 9
1500–1999 11 150–199 12
2000–2499 16 20–-249 15
2500–2999 16 250–299 22
3000–3499 14 300–349 6
3500 8 3500 6
Total 70 Total 70

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Table S8: Sampled Homes by Number of Stories
Stories Number of Homes
1 27
2 42

2.5 1
Total 70
Table S9: Sampled Homes by Number of Bedrooms
Bedrooms Number of Homes
1 1
2 3
3 20
4 28
5 17
6 1
Total 70
Table S10: Sampled Homes by Number of Bathrooms
Bathrooms Number of Homes
1–1.5 1
2–2.5 24
3–3.5 35
4–4.5 9
5–5.5 1
Total 70

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Table S11: Locations of Gas Fireplaces
Location Homes
Great room or living room 26
California room 3
Courtyard 1
Patio 2
No gas fireplace 38
Total 70
Household Demographics
HENGH homes are compared with data from American Housing Survey (2017 AHS). Data from the Public Use File (PUF)9 were used to compare with demographic data of HENGH homes. The PUF provided data for four California metropolitan areas that were surveyed in 2017: Los Angeles-Long Beach-Anaheim, San Francisco-Oakland-Hayward, Riverside-San BernardinoOntario, and San Jose-Sunnyvale-Santa Clara. The first three of the four metropolitan areas were included in the national survey, and the last one was included in the metropolitan survey. Data from owner-occupied, single-family detached homes built after 2010 were selected from the 2017 AHS data for comparison with HENGH homes in the tables below.

Table S12: Number of Occupants in Sampled Homes
Number of Occupants Number of Homes
in HENGH
% Homes in
HENGH
% Homes in 2017
AHS
1 3 4% 13%
2 29 43% 28%
3 10 15% 18%
4 13 19% 24%
5 6 9% 9%
6 3 4% 5%
7 or more 3 4% 2%
No response 3 -- --
Total 70 100% 100%

9 https://www.census.gov/programs-surveys/ahs/data/2017/ahs-2017-public-use-file--puf-.html

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Table S13: Number of Occupants in Sampled Homes by Age Group Number of
Occupants
Within Age
Group
Homes with Designated Number of Occupants in Designated Age Group Number of HENGH % HENGH Homes % Homes in 2017 AHS
Age
0–17
Age
18–65
Age
65+
Age
0–17
Age
18–65
Age
65+
Age
0–17
Age
18–65
Age
65+
0 41 8 49 60% 12% 72% 59% 12% 74%
1 7 7 10 10% 10% 15% 19% 17% 14%
2 14 41 9 21% 60% 13% 18% 42% 11%
3 3 8 0 4% 12% 0% 4% 15% 0%
4 2 2 0 3% 3% 0% 0% 9% 0%
5 or more 1 2 0 1% 3% 0% 0% 5% 0%
No response 2 2 2 -- -- -- -- -- --
Total 70 70 70 100% 100% 100% 100% 100% 100%
Table S14: Total Household Income in Sampled Homes
Income Range Number of Homes
in HENGH
% Homes in
HENGH
% Homes in 2017
AHS
$35,000–$49,999 1 2% 18%
$50,000–$74,999 2 3% 12%
$75,000–$99,999 5 8% 10%
$100,000–$150,000 29 44% 20%
Greater than $150,000 29 44% 40%
No response 4 -- --
Total 70 100% 100%

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Table S15: Education Level of Head of Household in Sampled Homes Education Level Number of Homes
in HENGH
% Homes in
HENGH
% Homes in 2017
AHS
No diploma 0 0% 6%
Completed high school 1 1% 16%
Some college 5 7% 15%
Associate’s degree 2 3% 7%
College degree 23 34% 30%
Graduate or professional degree 36 54% 26%
No response 3 -- --
Total 70 100% 100%
Air Tightness
Figure S3: Distribution of ACH50 from Envelope Leakage Measurements

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Ventilation and Filtration Equipment
Table S16: Whole House Ventilation System Type
System Type Operation Mode Fan Location(s) Number of Homes Exhaust Continuous Laundry Room 43
Bathroom 9
Attic 3
Intermittent Laundry Room 5
Bathrooms (multiple) 4
Supply Continuous Attic 4
Intermittent None* 2
Total 70
*These central fan integrated supply (CFIS) systems had a duct with motorized damper that connected the outdoors to the return side of the forced air system, but no supply fan.

Table S17: Whole House Ventilation System Control
Whole-House Ventilation Control Controller Labelled? % On As-Found On/Off Switch No (N=42) 5%
Yes (N=12) 58%
Programmable Controller No (N=10) 50%
Thermostat No (N=2) 0%
Breaker Panel No (N=1) 100%
No Controller No (N=3) 100%

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Figure S4: Bathroom Exhaust Fan Measured Flow Rates
Table S18: Air Filter MERV Ratings
MERV Number of Air Filters
6 2
7 2
8 57
10 17
11 22
12 1
13 9
14 1
Total 111

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Table S19: Time Since Last Air Filter Change
Marked or Estimated Time Number of Air Filters
0 to 2 Months 33
3 to 5 Months 16
6 to 8 Months 17
12 to 15 Months 8
Never Changed 11
Total 85
Table S20: Condition of Air Filters Observed by Field Team Air Filter Condition Number of Homes Number of Air Filters Clean or Like New 20 39
Used or Dirty 29 65
Very Dirty 18 24
Total 67* 128
* Total excludes one home (113) without a central forced air system (this home had a minisplit heat pump with no filter for air quality), one home (127) without any air filters installed in the return air registers, and one home (117) for which field observations were missing.

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Figure S5: Total Estimated Air Exchange Rate
This plot includes estimates for 63 homes. It excludes four homes that used supply ventilation because the mechanical airflow could not be determined. The plot also excludes three homes with missing DeltaQ test result because building envelope airtightness is required to calculate air infiltration (part of total ventilation). There are six homes (*) where opening of the house-to-patio and/or garage door(s) for more than 3 hours per day on average may have increased the overall AER substantially.

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Figure S6: Infiltration and Total Airflow (Mechanical + Infiltration) Mechanical airflow rates were calculated by summing all exhaust fans in a home. The estimated total outdoor airflow rates include both mechanical airflow and air infiltration. Data are plotted for 63 homes same as in Figure S5.

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General Occupancy and Sources – From Survey
Table S21: How Frequently Are Candles Used in the Home
Number of Homes
Never 13
A few times a year 23
A few times a month 16
A few times a week 11
Every day 5
No response 2
Total 70
Table S22: Number of Furry Pets in Homes
Occupancy and Sources During Week of Monitoring
Table S23: Self-Reported Average Occupancy (Number of People) When Home Was Occupied Average Occupancy Number of Homes Average Occupancy Number of Homes 1 to <2 People 23 5 to <6 People 4
2 to <3 People 20 6 to <7 People 3
3 to <4 People 14 No Response 2
4 to <5 People 4 Total 70
Number of Pets Number of Homes
0 20
1 17
2 12
3 3
4 or more 2
No response 16
Total 70

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Table S24: Self-Reported Average Occupied Hours per Day During Monitoring Week Number of Occupied Hours Number of Homes
> 23 Hours 16
20 to <23 Hours 27
16 to <20 Hours 17
12 to <16 Hours 3
6 to <12 Hours 3
< 6 Hours 2
No Response 2
Total 70
Table S25: Self-Reported Cooktop Use (Number of Times) During Monitoring Week Number of Cooktop Use Number of Homes
None 2
1–3 Times 16
4–6 Times 16
7–14 Times 26
15–21 Times 6
More than 21 Times 2
No Response 2
Total 70
Table S26: Self-Reported Oven and Outdoor Grill Use During Monitoring Week Number of Homes
Number of Uses Oven Outdoor Grill
None 16 52
1 Time 14 9
2–3 Times 21 7
4–5 Times 11 0
6–8 Times 6 0
No Response 2 2
Total 70 70

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Table S27: Average Cooking Activity Duration During One-Week Monitoring, Self-Reported Number of Homes
Use Duration Cooktop Oven Outdoor Grill
Less than 10 Minutes 3 3 0
10–30 Minutes 40 20 5
30–60 Minutes 20 24 8
>60 Minutes 3 5 3
No Usage Reported 2 16 52
No Response 2 2 2
Total 70 70 70
Table S28. CNHS Activities (Table 42 and 43 of Offermann et al. 2009):
- Toasting: n=50, median of 5 min
- Frying or sautéing: n=36, median of 17 min
- Baking: n=33, median of 45 min
- Broiling: n=11, median of 19 min
- Other cooktop: warming/boiling, n=47, median of 20 min - Vacuuming: n=16, median of 25 min
- Sweeping or dusting: n=16, median of 12 min
- Candle burning, n=4 events, median of 165 min.
- Aerosol air fresheners or personal care products: n=30 - Large party or dinner gathering: n=3
- Other activities: dust, smoke or fumes: n=3, median 30 min

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Air Pollutant Concentrations: Formaldehyde
Table S29 presents a comparison of formaldehyde measurements made at the main indoor site with the UMEx-100 time-integrated sampler and the weeklong average of the half-hourly resolved data obtained with the FM-801 monitor. Statistical significance tests suggest no difference in formaldehyde concentrations measured using the two methods: p-value = 0.09 (Student’s paired t-test).

Table S29: Comparison of Time-Integrated Formaldehyde Measured with Two Methods SKC UMEx-100
Passive Sampler
GrayWolf FM-801
Monitor
Indoor Main (ppb) N = 68 N = 69
Mean 19.8 18.9
Median 18.2 18.8
10th–90th Percentile 13–28 10–27
Similar to the finding (reported in the main paper) that formaldehyde measured by the UMEx was higher in the bedroom than at the main indoor site, FM-801 data collected in the bedroom also indicated higher period-averaged formaldehyde compared to data collected in the main indoor site (p-value = 4.5e-5 using Student’s paired t-test). Among the 65 homes with valid FM801 data in both locations, formaldehyde in the bedroom was >10% higher than in the living room in 35 homes and less than 90% in 4 homes. The median and 10th–90th ratios of bedroom to living room concentrations were 1.13 and 0.97–1.44. Using data from the FM-801, overnight concentrations in the bedroom were higher than the period-average at that location (p-value =

5.4e-6 using Student’s paired t-test). Formaldehyde in the bedroom overnight was >10% higher than the period-average living room in 38 homes and less than 90% in 3 homes. The median and 10th–90th ratios of bedroom overnight to period-average living room concentrations were 1.19 and 0.97–1.52.

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Air Pollutant Concentrations: PM2.5
A comparison of time-integrated PM2.5 measured with the MetOne and Thermo pDR photometers and co-located gravimetric samples are provided in Table S30. Table S30 Table S30. Time-integrated PM2.5 concentrations measured by MetOne and Thermo pDR-1500 photometers compared with gravimetric analysis of co-located filter samples.

House City Dates MetOne pDR Filter Filter/
MetOne
Filter/
pDR
Indoor PM2.5 (ug/m3)
025 Hayward 2017-03-23 to 03-30 3.7 4.5 4.7 1.3 1.1
026 Davis 2017-04-18 to 04-25 2.8 4.3 4.2 1.5 1.0
040 Discovery Bay 2017-05-23 to 05-30 2.1 3.2 2.8 1.3 0.9 029 Brentwood 2017-06-09 to 06-16 3.1 3.8 3.7 1.2 1.0
047 Clovis 2017-10-12 to 10-19 31.9 30.1 23.5 0.7 0.8
046 Clovis 2017-11-08 to 11-15 5.1 6.9 5.0 1.0 0.7
068 Manteca 2018-01-24 to 01-31 2.6 4.2 3.6 1.4 0.9
066 Manteca 2018-02-05 to 02-12 2.7 4.3 4.0 1.4 0.9
Outdoor PM2.5 (ug/m3)
025 Hayward 2017-03-23 to 03-30 NA 5.6 4.1 NA 0.7
026 Davis 2017-04-18 to 04-25 NA 3.4 4.4 NA 1.3
040 Discovery Bay 2017-05-23 to 05-30 4.5 5.1 4.8 1.1 0.9 029 Brentwood 2017-06-09 to 06-16 3.0 3.9 3.4 1.1 0.9
047 Clovis 2017-10-12 to 10-19 25.5 30.3 19.6 0.8 0.6
046 Clovis 2017-11-08 to 11-15 6.0 NA NA NA NA
068 Manteca 2018-01-24 to 01-31 20.2 18.2 10.6 0.5 0.6
066 Manteca 2018-02-05 to 02-12 14.0 12.4 5.6 0.4 0.4
Analysis of Regulatory Air Monitoring Data to Estimate PM2.5 Outside of HENGH Homes We investigated the possibility of using regulatory ambient air monitoring station data to develop correction factors for photometers outside of the homes. We identified up to three regulatory air monitoring stations near each of the study home. Figure S1 show locations of the air quality monitoring stations in relationship to the study home. The air monitoring stations were all located within 30 km of the study home, selected to broadly represent the air quality at that location. Air monitoring stations sited to monitor near-road concentrations (located within 100 m of a major roadway) were excluded to avoid biases from traffic emissions. The daily mean PM2.5 were obtained from AQMIS.

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We applied inverse distance weighting to calculate the daily mean PM2.5 at the study home, and calculated the mean PM2.5 for the monitoring period (~6 days). Results of the inverse distance weighted ambient monitoring data are compared with the outdoor PM2.5 measured using MetOne photometer in Error! Reference source not found..

Table S31 shows the differences in mean PM2.5 measured using the MetOne photometer and inverse distance weighted ambient monitoring data. Because the ambient monitoring data obtained from AQMIS are daily means, the results presented in Table S31Table S31 considered only days with full 24-h data as monitored by the MetOne photometer (i.e., partial days on first and last day of monitoring were excluded). The mean, median, and 10th percentile estimates of PM2.5 measured by the MetOne photometer were less than what was measured at the corresponding ambient monitoring station. This suggests that the MetOne photometer may have underestimated the outdoor PM2.5 relative to the ambient monitoring data at some of the homes.

However, the reverse is true for other homes such that the MetOne photometer measurements were higher than the ambient monitoring data when compared at 90th percentile. No correction factor is applied to outdoor MetOne because of a lack of consistency when compared with the ambient monitoring data.

Table S31. Summary statistics (N=67) of the mean outdoor PM2.5 measured using MetOne photometer and inverse distance weighted ambient monitoring data.

MetOne photometer
(ug/m3)
Nearby ambient air quality
monitoring stations (ug/m3)
Mean 9.3 10.5
Median 6.8 9.7
10th–90th 2.7–18.1 5.3–16.7

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Figure S7. Comparison between mean outdoor PM2.5 measured using MetOne photometer and inverse distance weighted ambient monitoring data (N=67).

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Air Pollutant Concentrations: Nitrogen Dioxide and Nitric Oxide Figure S8: One-Week Integrated NO2, NO, and NOx Concentrations Ranked ordered by indoor concentrations (blue circles), with corresponding outdoor concentrations plotted as black crosses.

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Air Pollutant Concentrations: CO2
Figure S9: Overnight (midnight-5am) CO2 measurements in indoor main living space and master bedroom.

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IEQ Satisfaction by Ventilation System Operation
Tables S33 to S35 present air quality and comfort satisfaction reported by participants, divided by whether the dwelling unit ventilation system was operating when the research team arrived to the home. The Fisher’s exact test for count data was performed to determine if there is an association between the ventilation system operating at that time and satisfaction. Survey responses for satisfaction were scored using a scale between 1 and 9. For the Fisher’s test, satisfaction responses were classified into four groups: dissatisfied (1–4), neutral (5), satisfied (6–7), and very satisfied (8–9). Survey responses for frequency of a discomfort were provided using a 5-level scale: (i) never, (ii) a few times a year, (iii) a few times a month, (iv) a few times a week, and (v) every day. For the Fisher’s test, frequency responses were classified into two groups: infrequent (i, ii, or iii) and frequent (iv or v).

Table 32. Air quality satisfaction reported by participants.

To what extent are you
satisfied or dissatisfied with
indoor air quality in your
home?
How would you rate the
outdoor air quality where
you live?
How would you rate your
home in protecting you
from outdoor air pollution?
Ventilation
As-Found
Off On Off On Off On
Dissatisfied 3 3 11 8 3 2
Neutral 13 3 9 2 18 3
Satisfied 17 4 17 6 15 6
V. Satisfied 17 8 10 2 14 7
p-value 0.375 0.413 0.444
Table 33. Satisfaction with seasonal temperature conditions by ventilation system status on first visit to home.

Winter / Some
rooms are too hot1
Winter / Some
rooms are too cold1
Summer / Some
rooms are too hot1
Summer / Some
rooms are too cold1
Ventilation
As-Found
Off On Off On Off On Off On
Infrequent 41 13 36 10 37 9 45 15
Frequent 6 4 12 8 13 9 2 1
p-value 0.435 0.144 0.081 1
1 Survey question: In [season], how often is the temperature in your home uncomfortable to any occupants because [condition]?

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Table 34. Satisfaction with environmental parameters by ventilation system status on first visit to home.

Too much air
movement
Not enough air
movement
Indoor air is
too dry
Indoor air is
too damp
Indoor air has
musty odor
Ventilation
As-Found
Off On Off On Off On Off On Off On
Infrequent 48 18 41 11 43 17 49 18 48 17
Frequent 1 0 8 7 5 1 1 0 1 0
p-value 1 0.094 1 1 1
1 Survey question: How often do the following conditions affect the comfort of occupants in your home? Frequent is on weekly or daily basis.

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Recruitment Postcard

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Daily Activity Log
Provided below is the top page of the activity log. Participants were asked to complete a log table for each calendar day during which measurements were being made in the home. Participants were provided with paper sheets containing a log for each day.

Healthy Efficient New California Homes Study
Occupancy and Indoor Activities Data Log
Instructions: Please fill out this data log each day, or on the following day.

Please enter your best estimates. If you are unsure, please provide your best guess.

Do not list the names of any people.

Code number for home _________
Day 1: Date __________________ Date completed _______________ Midnight
to 7am
7am to
11am
11am to
1pm
1pm to
5 pm
5pm to
9pm
9pm to
Midnight
Number of people
in home
Cooktop use
Number of minutes
Oven use
Number of minutes
BBQ/outdoor grill
Number of minutes
Vacuuming
Number of minutes
Window Use
Number of minutes
Other notable*
indoor/outdoor events
* For example, use of fireplace, candle, air freshener, air cleaner, humidifier, unusual outdoor air quality (wood smoke, wildfire), and so on.

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-40
Occupant Survey
Welcome to the 2015 California New Homes Survey!
This survey is part of a research study on new homes in California. This research will help inform how new homes can provide adequate ventilation and good indoor air quality, while reducing air infiltration and energy use.

This survey takes about 15 minutes to complete. It asks questions about your home, household activities, and demographics. You can skip questions that you do not want to answer.

This research is being conducted by Lawrence Berkeley National Laboratory (LBNL) with funding from the California Energy Commission. Results will be used only for research on how to provide adequate ventilation and improve indoor air quality. In order to protect your privacy, the data will be encrypted and password protected.

Please return your completed survey in the envelope provided.

If you have questions about the research study, please contact:

Max Sherman, Ph.D.

Principal Investigator, Residential Building Systems Group Lawrence Berkeley National Laboratory
[email protected] (510) 486 4022
Code number for home _________ Date completed _______________

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-41
Please answer to the best of your knowledge. You can skip any questions that you do not want answer.

A. Home and Household Characteristics

1. What year was your house built?
Year Built: ………………

2. What is the size (floor area) of your home?
Square Feet: ………………

3. What year did you move into this home?
Year Moved In: ……………….

4. Do you own or rent your home?
……. Own (If yes  5, skip otherwise)
……. Rent
……. Other

5. Are you the first owner of the property? Yes / No

6. How many people currently live in your home?
Number of People: ……………..

B. Air Quality In and Around Your Home

7. To what extent are you satisfied or dissatisfied with the indoor air quality in your home? Very
Dissatisfied
Neutral Very
Satisfied
☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐

8. How would you rate the outdoor air quality near where you live? Very
Poor
Neutral Excellent
☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐

9. How would you rate your home in protecting you from outdoor air pollution? Very
Ineffective
Neutral Very
Effective
☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-42
C. Comfort Level in Your Home

10. In winter, how often is the temperature in your home uncomfortable to any occupants because some room(s) are too hot or too cold?
Never Few times
a year
Few times
in a month
Few times
a week
Every
day
Too hot in some room(s). ☐ ☐ ☐ ☐ ☐
Too cold in some room(s). ☐ ☐ ☐ ☐ ☐

11. In summer, how often is the temperature in your home uncomfortable to any occupants because some room(s) are too hot or too cold?
Never Few times
a year
Few times
a month
Few times
a week
Every
day
Too hot in some room(s). ☐ ☐ ☐ ☐ ☐
Too cold in some room(s). ☐ ☐ ☐ ☐ ☐

12. How often do the following conditions affect the comfort of occupants in your home? Never Few times
a year
Few times
a month
Few times
a week
Every
day
Too much air movement. ☐ ☐ ☐ ☐ ☐
Not enough air movement. ☐ ☐ ☐ ☐ ☐
Indoor air is too dry. ☐ ☐ ☐ ☐ ☐
Indoor air is too damp. ☐ ☐ ☐ ☐ ☐
Indoor air has musty odor. ☐ ☐ ☐ ☐ ☐

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-43
D. Natural Gas Appliances and Mechanical Ventilation

13. Which of the following heating appliances are used in your home? Select all that apply. ..….. Central gas furnace
……. Gas fireplace/ log set
….... Gas wall furnace
……. Freestanding gas heater
……. Central electric heating or heat-pump
……. Baseboard electric wall heater
……. Freestanding electric heater
……. Wood fireplace
……. Freestanding propane heater
……. Freestanding kerosene heater
……. Other. Please describe: ...………………………….
……. Don’t know

14. How often is the kitchen range hood or kitchen exhaust fan used when cooking with a cooktop?
……. Always (5 out of 5 times)
……. Most of the Time (4 out of 5 times)
……. Sometimes (2 to 3 out of 5 times)
……. Rarely (1 out of 5 times)
……. Never (0 out of 5 times)
……. Don’t know

15. If the kitchen range hood or kitchen exhaust fan is NOT always used, what are the reasons for not using it? Select all that apply.
……. Forget to turn it on
……. Not needed for what is being cooked
……. Too noisy
……. Doesn’t seem to remove cooking fumes or odors
……. Open window instead
……. Uses too much energy
……. Other. Please describe: ……………........................................

16. Was the operation of the mechanical ventilation system explained to you when you bought or moved into the home?
……. Yes
……. No
……. Don’t know

17. Do you feel you understand how to operate your mechanical ventilation system properly? ……. Yes
……. No
……. Not Sure

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-44

18. To what extent are you satisfied or dissatisfied with your mechanical ventilation system? Very
Dissatisfied
Neutral Very
Satisfied
☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐ ☐

19. If you are NOT very satisfied with your mechanical ventilation system, what are the reason(s) for dissatisfaction? Select all that apply.
……. Too noisy
……. Too drafty
……. Difficult to operate
……. Difficult to maintain
……. Uses too much energy
……. Brings in dust, odor, or air pollutants from outdoor ……. Not effective
……. Other. Please describe: ………………………………….

E. Occupancy and Indoor Activities

20. On average, how many hours per day is your home occupied by at least one person, including day and night hours?
Fewer than 8
hours per
day
8 to 12 hours
per day
12 to 16
hours per
day
16 to 20
hours per
day
More than 20
hours per
day
Weekday ☐ ☐ ☐ ☐ ☐
Weekend ☐ ☐ ☐ ☐ ☐

21. On average, how many times per week is your cooktop and/or oven used for cooking, including boiling water?
0 time
per week
1 to 2 times
per week
3 to 4 times
per week
5 to 6 times
per week
7 times
per week
Breakfast ☐ ☐ ☐ ☐ ☐
Lunch ☐ ☐ ☐ ☐ ☐
Dinner ☐ ☐ ☐ ☐ ☐
Other cooking ☐ ☐ ☐ ☐ ☐

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-45

22. On average, how many times per week do the following activities occur inside your home? Enter “0” if occurrence is less frequent than once a week.

Use shower (Times per week) …………………
Use bath or indoor Jacuzzi (Times per week) …………………
Use dishwasher (Times per week) …………………
Use washing machine (Loads per week) ………………..

Hang clothes to dry indoors (Loads per week) ………………..

F. Window Opening

23. On average, how many hours per day are your windows open? 0 hour per
day
1 to 2 hour
per day
2 to 8 hours
per day
8 to 16
hours per
day
More than 16
hours per day
Summer ☐ ☐ ☐ ☐ ☐
Fall ☐ ☐ ☐ ☐ ☐
Winter ☐ ☐ ☐ ☐ ☐
Spring ☐ ☐ ☐ ☐ ☐
G. Indoor Activities

24. On average, how often do the following activities occur inside your home? Never Few times
a year
Few times
a month
Few times
a week
Every
day
Smoking ☐ ☐ ☐ ☐ ☐
Burn candle or incense ☐ ☐ ☐ ☐ ☐
Vacuuming ☐ ☐ ☐ ☐ ☐
Use cleaning agent for floor
cleaning
☐ ☐ ☐ ☐ ☐
Use spray air freshener ☐ ☐ ☐ ☐ ☐
Use pesticide spray ☐ ☐ ☐ ☐ ☐
Use paints, glue, solvents (e.g.,
hobbies, home repairs)
☐ ☐ ☐ ☐ ☐
Use humidifier ☐ ☐ ☐ ☐ ☐
Use dehumidifier ☐ ☐ ☐ ☐ ☐

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-46
H. Other Indoor Sources

25. Are plug-in or stick air fresheners, or other scented decorations, used in your home? ……. Yes
……. No
……. Don’t know

26. Do occupants wear shoes in your home?
……. Yes
……. No
……. Don’t know

40. How many dogs, cats, or other furry pets are in the home? Number of Pets: ………………
I. Use of Air Cleaners

27. Do you use a stand-alone (portable) air filter, air purifier, or air cleaner in the home? ……. Yes
……. No
……. Don’t know

28. Where is your stand-alone (portable) air filter, air purifier, or air cleaner located in your home? Select all that apply.
……. Master bedroom
……. Other bedroom(s)
……. Living room
……. Home office
……. Other. Please describe: ……………........................................

29. Has anyone in the household been diagnosed with asthma? ……. Yes
……. No
……. Don’t know

30. Has anyone in the household been diagnosed with allergies? ……. Yes
……. No
……. Don’t know

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-47
J. Demographic Information
The next questions will help us interpret the results of the survey. All responses will be kept confidential.

31. Please indicate the number of household member(s) in the following age categories.

Number of household member(s)
0 to 17 Years Old ……………………
18 to 65 Years old ……………………
Over 65 Years old ……………………

32. What is the highest education level of head of household? …….. No schooling completed
…….. 1 to 8th grade
…….. 9th to 12th grade
…….. Completed high school (high school diploma, GED credential) …….. Some college
…….. Associate’s degree
…….. College degree (Bachelor’s degree)
…….. Graduate degree (Master’s, Professional school, Doctorate degree)

33. Please indicate all races and/or ethnicities of people living in your household. …….. American Indian, Alaska Native
…….. Asian or Pacific Islander
…….. Black, African American
…….. Hispanic/ Latino
…….. White, Caucasian
…….. Other, specify: ………………….
…….. Mixed race, specify: ………………….

34. What is the total income of all member(s) of your household combined? …….. Less than $35,000
…….. $35,000 to $ 49,999
…….. $50,000 to $ 74,999
…….. $75,000 to $ 99,999
…….. $100,000 to $150,000
…….. Greater than $150,000
K. End of Survey
Thank you for filling out this survey! Your data is very valuable to our understanding of indoor air quality and mechanical ventilation in new California homes.

Please return your completed survey in the envelope provided.

If you have any questions about the survey, please contact: [LBNL contact provided]

IAQ in Mechanically Ventilated U.S. Homes INA-19-10-297-R2 04-April-2020 SI-48

CONSENT CALENDAR

CITY OF SHAFTER

CITY COUNCIL REPORT
MEETING DATE: October 20, 2026
DEPARTMENT: Ravi Pudipeddi, City Engineer
SUBJECT: AUTHORIZATION OF NOTICE OF COMPLETION AND
ACCEPTANCE OF WORK FOR TRACT 7318 PHASES 1 AND 3

RECOMMENDATION
Council find the action is not a “project” as defined by Section 15378(b)(5) of the CEQA Guidelines; accept the public improvements constructed for Tract 7318 Phases 1 and 3; authorize the City Engineer to file a Notice of Completion and Acceptance of Work for the tract; and authorize the reduction of performance bond securities to 25% of their original value to act as a warranty bond for a minimum of one year.

BACKGROUND
KC Builders Collaborative LLC (KC Builders) has completed the required public improvements for Tract 7318 Phases 1 and 3. Completed improvements include earthwork, water, sewer, storm drain facilities, curbs, gutters, medians, perimeter walls, street paving, street lighting, sidewalks, and underground utilities, including City fiber service. The applicable work has been completed per the approved plans by Public Works staff. The City Council has previously approved public improvements for Tract 7318 Phase 2 in June 2024.

KC Builders previously filed performance bonds with the City to cover 100% of the proposed construction cost of the public improvements for Tract 7318 Phases 1 and 3.

The bonds, included in the Subdivision Improvement Agreement between KC Builders and the City, ensure faithful performance in constructing the public improvements.

Upon the City Engineer's recommendation, the bond amount can be reduced to 25% of the proposed construction costs for phases 1 and 3 as public improvements are accepted by the Council.

FISCAL IMPACT
No budget action is required. Future operating and maintenance budgets will be adjusted to ensure adequate funding once the City assumes responsibility for the public improvements.

CEQA ANALYSIS
The action is not a “project” as defined by Section 15378(b)(5) of the CEQA Guidelines because it is approval to authorize a notice of completion and acceptance of work for a tract that has already been environmentally cleared, which is an organizational or

AUTHORIZATION OF NOTICE OF COMPLETION AND ACCEPTANCE OF WORK FOR TRACT 7318 PHASES 1 AND 3
- 2 -
administrative activity that will not result in direct or indirect physical changes to the environment.

APPROVED BY THE CITY ATTORNEY
Not Applicable

ATTACHMENTS
None

CONSENT CALENDAR

CITY OF SHAFTER

CITY COUNCIL REPORT
MEETING DATE: October 20, 2026
DEPARTMENT: Michael James, Assistant City Manager, Alex Gonzalez, Public Works Director
SUBJECT: AUTHORIZE TO AMEND PROFESSIONAL SERVICES

AGREEMENT FOR HIGHWAY SAFETY IMPROVEMENT
PROGRAM CYCLE 13 GRANT APPLICATIONS

RECOMMENDATION
Council find the action action is not a “project” as defined by Section 15378(b)(5) of the CEQA Guidelines; authorize scope of work additions to a current professional services agreement with TJKM (Purchase Order No. 252) for an amount not to exceed $32,000, increasing said agreement to a total value of $222,200.60; direct award said scope of work additions to TJKM pursuant to the competitive bidding exemptions identified in Shafter Municipal Code Sections 2.68.030(b)(3) and 2.68.030(b)(4), based on time-sensitive Highway Safety Improvement Program (HSIP) Cycle 13 application deadline and the consultant's ongoing preparation of the City's Comprehensive Safety Action Plan; authorize the City Manager to execute the agreement amendment; and authorize City staff and the Shafter Police Department to prepare letters of support for each grant application, with the Public Works Director and Shafter Police Chief authorized to jointly sign and submit the letters on behalf of the City.

BACKGROUND
The City of Shafter is currently working with TJKM Transportation Consultants (TJKM) to prepare a Comprehensive Safety Action Plan (CSAP) funded through the U.S.

Department of Transportation's Safe Streets and Roads for All (SS4A) Grant Program.

On November 4, 2025, the City Council authorized a professional services agreement with TJKM to develop the CSAP, which will identify and prioritize transportation safety improvements throughout the City based on collision data, roadway conditions, and community input. The City Council approved the Agreement for an amount not to exceed $190,200.60.

On July 21, 2026, TJKM provided the City Council with an update on the CSAP, including preliminary collision analysis, identification of high-injury corridors and intersections, and community outreach activities. The analysis identified locations throughout the City where targeted improvements could reduce traffic collisions and improve roadway safety. As development of the CSAP continues, the City has an opportunity to pursue grant funding to advance the implementation of identified safety improvements.

AUTHORIZE TO AMEND PROFESSIONAL SERVICES AGREEMENT FOR HIGHWAY SAFETY IMPROVEMENT PROGRAM CYCLE 13 GRANT APPLICATIONS
- 2 -
The Highway Safety Improvement Program (HSIP), administered by the California Department of Transportation (Caltrans), provides federal funding to local agencies for projects intended to reduce traffic fatalities and serious injuries on public roadways. The HSIP Cycle 13 funding opportunity allows the City to seek funding for eligible safety improvements identified through the CSAP. TJKM has submitted a proposal to prepare up to three additional HSIP Cycle 13 grant applications: two Benefit-Cost Ratio (BCR) applications and one Funding Set-Aside application. These applications would be in addition to the grant application services included in TJKM's existing CSAP agreement.

The proposed services include evaluating candidate projects, reviewing collision and traffic data, developing project scopes and planning-level cost estimates, preparing required safety analyses, and completing application narratives and supporting documentation.

Section 2.68.020 of the Shafter Municipal Code (Purchasing) provides that “[D]ollar increases to existing contracts require the sum of the original contract to be added to the amount of the amendment to determine the single transaction value.“ The value of the original agreement was $190,200.60, and the value of the proposed amendment is (not to exceed) $32,000. Under Section 2.68.220 of the Shafter Municipal Code, professional services agreements between $10,000.01 and $100,000 are ordinarily subject to informal procurement procedures requiring solicitation of at least three proposals, unless an applicable exemption exists. However, Section 2.68.030(b) identifies circumstances that may justify an exemption from competitive bidding, including situations where solicitation of proposals would be unavailing or impossible and the procurement of professional or specialized services. In this case, staff finds a solicitation would be unavailing because TJKM has become intimately familiar with the City’s traffic infrastructure, conditions and improvement needs. This familiarity would greatly assist their development of grant applications and better position the City for selection. Selection of professional services is based upon demonstrated competence and whether the firm selected meets the needs of the City and its project. For these reasons, staff finds pursuing a solicitation would be unavailing.

The HSIP Cycle 13 grant application deadline in early November does not provide sufficient time to complete an informal procurement process, select and engage a new consultant, and prepare the required applications. Conducting an informal procurement process at this stage would prevent the City from submitting the applications before the deadline and would result in losing the current funding opportunity. TJKM is currently preparing the City's CSAP and has already performed much of the underlying collision analysis, roadway safety evaluation, and identification of potential safety improvements necessary to develop HSIP applications. The consultant's familiarity with the City's transportation safety needs and existing technical data will allow work on the additional applications to begin without the time required to procure and onboard another consultant.

Based on these circumstances, staff recommends that the City Council authorize an amendment to the current agreement and approve a direct award to TJKM pursuant to the competitive bidding exemptions identified in Shafter Municipal Code Sections

AUTHORIZE TO AMEND PROFESSIONAL SERVICES AGREEMENT FOR HIGHWAY SAFETY IMPROVEMENT PROGRAM CYCLE 13 GRANT APPLICATIONS
- 3 -

2.68.030(b)(3) and 2.68.030(b)(4). This approach will maintain continuity with the ongoing CSAP and allow the City to pursue the current HSIP funding opportunity.

FISCAL IMPACT
The proposed amendment to TJKM's existing professional services agreement to include up to three HSIP Cycle 13 grant applications will cost no more than $32,000. The City's existing recurring transportation-related revenue sources will support the increased expenditures, which may include Gas Tax revenues, traffic safety-related proceeds, or other eligible transportation funds. The City's adopted budget includes sufficient funding to cover the proposed expenditure. Accordingly, no additional appropriation or budget amendment is required.

CEQA ANALYSIS
The proposed action is not a project under the California Environmental Quality Act (CEQA) pursuant to Section 15378(b)(5) of the CEQA Guidelines because it involves authorization of professional services for the preparation of grant applications and does not approve or commit the City to the construction of any physical improvements. Any projects subsequently proposed for implementation would be subject to separate environmental review, as applicable.

APPROVED BY THE CITY ATTORNEY
Yes

ATTACHMENTS

1. HSIP Grant Application Proposal Submitted by TJKM

CALIFORNIA | FLORIDA | TEXAS
Corporate Office 4305 Hacienda Drive, Suite 550, Pleasanton, CA 94588 925.463.0611 www.TJKM.com
Dear Michael,
TJKM Transportation Consultants is pleased to submit our Scope of Work and Level of Effort to the City of Shafter for the preparation of Highway Safety Improvement Program (HSIP) Cycle 13 grant applications.

TJKM understands that the City is seeking assistance in preparing three (3) HSIP Cycle 13 grant applications to support transportation safety improvements throughout the City.

The applications consist of:
• Two (2) Benefit-Cost Ratio (BCR) applications.
• One (1) Funding Set-Aside application.

Our approach to each application is grounded in our team’s extensive experience with state and federal transportation grants. Based on this experience, we believe the most critical components for successfully securing grant funding include:
• Grant and data research
• Narrative writing
• Cost Estimates
• Maps/Diagrams
• Strong supporting documentation
With a proven track record of helping local agencies secure transportation funding through programs such as HSIP, Safe Streets and Roads for All (SS4A), California Office of Traffic Safety (OTS)and the Active Transportation Program (ATP), TJKM is well positioned to assist the city in developing competitive HSIP Cycle 13 applications.

Date: September 28, 2026
To: Michael James
Assistant City Manager
City of Shafter
336 Pacific Avenue, Shafter, CA 93263
Email: [email protected]
From: Ruta Jariwala, P.E., T.E.

Subject: Proposal to Assist the City of Shafter in the Preparation of HSIP Cyle 13 Grant Applications

Proposal for HSIP Cycle 13 Grant Application, City of Shafter August 4, 2026
2 Scope of Work
Upon execution of the contract, TJKM will meet with City staff to review candidate projects, confirm eligibility, and identify the most competitive projects for HSIP Cycle 13 funding. For each application, TJKM will provide the following services:
• Project Scoping: Review project limits, identify proposed safety improvements, develop conceptual project descriptions, prepare planning-level cost estimates, and develop supporting exhibits.
• Safety Analysis: Compile and evaluate collision history, roadway characteristics, traffic data, and other supporting information necessary for the applications. • Narrative Development: Prepare compelling technical narratives describing project need, safety benefits, and consistency with HSIP program objectives. • Grant Documentation: Prepare required maps, collision summaries, cost estimates, photographs, engineer's checklists, and other supporting documentation.
• Application Preparation and Coordination: Complete all required Caltrans HSIP application forms, coordinate with City staff, incorporate City review comments, and prepare final submission-ready application packages.

Benefit-Cost Ratio (BCR) Applications
• For the two (2) BCR applications, TJKM will prepare the required HSIP Analyzer documentation, develop planning-level cost estimates, perform Crash Modification Factor (CMF) evaluations, calculate Benefit-Cost Ratios (BCR), and prepare all supporting technical documentation required by Caltrans.

Funding Set-Aside Application
• For the Funding Set-Aside application, TJKM will prepare the required HSIP Analyzer documentation, develop the technical narrative and supporting exhibits, and complete all required application forms and attachments.

Deliverable:

TJKM will deliver three (3) complete, submission-ready HSIP Cycle 13 grant application packages consisting of two (2) Benefit-Cost Ratio (BCR) applications and one (1) Set-Aside application. Each package will include all required Caltrans application forms, HSIP Analyzer files, benefit-cost analyses (as applicable), engineer's checklists, project cost estimates, collision analyses, project narratives, location maps, exhibits, supporting documentation, and all required attachments. Draft application packages will be prepared and submitted to the city for review. Following incorporation of the City's comments, the

Proposal for HSIP Cycle 13 Grant Application, City of Shafter August 4, 2026
3 applications will undergo a comprehensive quality assurance/quality control (QA/QC) review and be finalized prior to submission.

Fee and Schedule
Based on the estimated level of effort, TJKM proposes a lump-sum, not-to-exceed fee for the preparation of three HSIP Cycle 13 applications. Final application packages will be completed in accordance with the Caltrans HSIP Cycle 13 schedule and submitted prior to the established deadline.

Table 1: Level of Effort for Grant Applications
# Grant Application Number of Applications Lump Sum Fee 1 Prepare HSIP Cycle 13 BenefitCost Ratio (BCR) Applications 2 $24,000 2 Prepare HSIP Cycle 13 Funding
Set-Aside Application 1 $8,000
Total Three (3) HSIP Cycle 13
Applications 3 $32,000
Thank you for considering TJKM Transportation Consultants for this engagement. We appreciate the opportunity to assist the City of Shafter with its HSIP Cycle 13 funding efforts and look forward to working with you. If you have any questions or require additional information, please feel free to contact us.

Sincerely,
TJKM Transportation Consultants
Ruta Jariwala
Vice President/Project Manager

MANAGEMENT REPORT

CITY OF SHAFTER

CITY COUNCIL REPORT
MEETING DATE: October 20, 2026
DEPARTMENT: David Franz, Community Services Director
SUBJECT: MURAL DESIGN COMMITTEE

RECOMMENDATION
Council provide staff direction on the formation of a Mural Design Review Committee for the 2027 calendar year. Staff recommends one student from each of the six public schools in Shafter (Golden Oak, Redwood, Sequoia, Richland Junior High, Grow Academy, and Shafter High), along with one appointee from each Councilmember. No formal action is requested at this time. If Council supports the recommended structure, nominations and appointments can be made at a future meeting.

BACKGROUND
Chapter 15.51 of the Shafter Municipal Code outlines a process for a Mural Design Review Committee to review mural proposals and make recommendations to Council for approval. Convening a committee for a defined period has the potential to increase public input and make the process more efficient by gathering site suggestions, reviewing designs, and bringing a coordinated slate of recommendations to Council.

The proposed process includes wall murals on buildings and micro-murals on smaller features such as book benches and electrical boxes. Both project types would qualify for a 50 percent City match in the downtown area (bounded by Shafter Avenue, Lerdo Highway, and Central Valley Highway), with the community raising the remaining 50 percent. Sites subject to owner consent and applicable requirements.

The proposed committee would serve during the 2027 calendar year, subject to Council direction and appointments at a future meeting.

Following future appointments, the committee would gather community site suggestions and artist designs, consider resident input, and recommend a slate of projects to Council in June 2027. Council would provide input and consider approval of the proposed slate. Approved projects would raise their community match and complete the work within six months of approval.

Wall mural proposals would follow Municipal Code Chapter 15.51, including applicable downtown requirements and Council consideration after public notice and an opportunity for comment. Wall murals also require a maintenance agreement between the City and building owner, approved by the Community Development Director,

MURAL DESIGN COMMITTEE
- 2 -
recorded with the Kern County Recorder, and effective for at least 15 years. Staff would identify applicable site and approval requirements for micro-murals as proposals are developed.

FISCAL IMPACT
The adopted budget includes $75,000, with $20,000 reserved for downtown banners and $55,000 available for the City's share of wall murals and micro-murals. No new funding action is requested.

Purpose City allocation
Wall mural and micro-mural matching funds $55,000
Downtown banners $20,000
Total adopted budget $75,000
If the full $55,000 City match is used, an equal community contribution would support $110,000 in wall mural and micro-mural projects. Actual expenditures would depend on the slate approved by Council and the matching funds raised for each project.

CEQA ANALYSIS
This item is for Council discussion and direction only. No committee formation, appointments, project approvals, or physical improvements are being authorized at this meeting. Accordingly, this discussion does not trigger CEQA review. Staff would evaluate applicable environmental review requirements when future actions are presented for approval.

APPROVED BY THE CITY ATTORNEY

ATTACHMENTS

1. Citywide Mural and Micro-Mural Process – Council Presentation

CITY OF SHAFTER · COMMUNITY SERVICES
Mural Design Committee Process
A community-supported, 50% matching approach to public art SHAFTER CITY COUNCIL · 2026

Current and Proposed Process
Current
• Each mural is a separate request
• Owners or artists must bring a complete proposal to
the City
Proposed
• One process each year, citywide
• Residents suggest sites and give input
• Council approves a slate of projects
• The community raises the 50% match and helps
paint
CITY OF SHAFTER · COMMUNITY SERVICES 2

How Community Members Take Part
Suggest a site
Anyone can suggest a
wall, bench, or electrical
box anywhere in the city.

Give input
Residents comment on
sites and designs before
the committee makes its
recommendations.

Raise funds
Donations, sponsorships,
and fundraisers provide
the 50% match.

Help paint
Painting days can be
coordinated with the
City’s quarterly
community service days.

CITY OF SHAFTER · COMMUNITY SERVICES 3

Project Types
Two types of projects, anywhere in the city. Both qualify for the 50% match.

Wall murals
Murals on building walls, with the owner’s consent.
50% CITY MATCH
Micro-murals
Smaller painted features such as book benches and
electrical boxes.
50% CITY MATCH
CITY OF SHAFTER · COMMUNITY SERVICES 4

Funding
50%
Paid by the City
50%
Raised by the community
$55,000
Available for the City match
Matching funds can come from residents, businesses, property owners, the Friends of the Shafter Library, service clubs, schools, and community fundraisers.

The adopted budget includes $75,000. Of that, $20,000 is reserved for downtown banners.

CITY OF SHAFTER · COMMUNITY SERVICES 5

Approval Process
1 Committee formed
January. Schools and
Council Appointees
2 Committee
gathers sites and
designs
Site suggestions from the
community and a call for
artist designs
3 Committee
recommends slate
to Council
June, for Council input
and approval
4 Funds raised,
work completed
Within six months of
approval
Per Municipal Code Chapter 15.51. Additional requirements apply in the downtown area. Wall murals also require a recorded 15-year maintenance agreement.

CITY OF SHAFTER · COMMUNITY SERVICES 6

Examples of Possible Wall Locations
Downtown examples shown for illustration. Sites anywhere in the city may be suggested, and owners must agree.

CITY OF SHAFTER · COMMUNITY SERVICES 7

Examples of Possible Micro-Murals
CITY OF SHAFTER · COMMUNITY SERVICES 7

Proposed Timeline
January 2027
• Committee formed
• Public call for site
suggestions
February–May
• Community input on sites
and designs
• Committee prepares slate
June 2027
• Slate to Council for input and
approval
July–December
• Approved projects raise 50%
match
• Painting days with quarterly
community service days
• Work completed
CITY OF SHAFTER · COMMUNITY SERVICES 8

REQUESTED ACTION
Consider Nominations for Mural Design
Review Committee
No new funding action is needed. The committee will bring a slate of projects to Council in June.

MANAGEMENT REPORT

CITY OF SHAFTER

CITY COUNCIL REPORT
MEETING DATE: October 20, 2026
DEPARTMENT: Ravi Pudipeddi, City Engineer
SUBJECT: DISCUSSION AND DIRECTION REGARDING THE APPLICATION

OF UNDERGROUND UTILITY REQUIREMENTS UNDER ZONING
ORDINANCE SECTION 10.380

RECOMMENDATION
Council find that the proposed action is not a “project” pursuant to CEQA Guidelines Section 15378(b)(5); discuss the continued application of the underground utility requirements established under Section 10.380 of the City of Shafter Zoning Ordinance to new development projects throughout the City; provide direction to Staff regarding the continued implementation of the existing requirements or the evaluation of potential ordinance modifications for future City Council consideration.

BACKGROUND
The Floyd’s Retail-Warehouse and Open Storage Buildings project (Project), located at the southeast corner of East Lerdo Highway and South Elm Street (Assessor’s Parcel Number 028-180-13), is proposed within the Business Park (BP) zoning district. As part of the Site Plan Review process, the Project was conditioned to underground existing overhead electrical facilities along its frontage, consistent with Section 10.380 of the City of Shafter Zoning Ordinance. The applicant has raised concerns regarding the cost associated with this requirement, prompting a broader discussion regarding the application of the City's underground utility requirements to new development projects.

Section 10.380, Underground Utilities, of the City of Shafter Zoning Ordinance establishes requirements for the installation of existing and proposed utility lines underground in conjunction with new development. These requirements generally apply to utility lines providing service to a development, located within the development property, within adjacent street frontages, or along the project perimeter. The ordinance places responsibility for coordinating and paying for the required undergrounding improvements on the developer or property owner. The undergrounding requirements provide a mechanism for the gradual conversion of overhead utility infrastructure to underground facilities as development occurs throughout the City.

Section 10.380 also establishes certain exceptions and provides an appeal process through which the City Council may consider waiving all or portions of the undergrounding requirements when topographic conditions, soil conditions, or other factors render underground installation unreasonable or impractical.

DISCUSSION AND DIRECTION REGARDING THE APPLICATION OF UNDERGROUND UTILITY REQUIREMENTS UNDER ZONING ORDINANCE SECTION 10.380 - 2 -
The Floyd's project illustrates the concerns that may arise when applying these requirements to existing overhead infrastructure. Although underground conduits have already been installed along the Project frontage, the applicant has raised concerns regarding the cost of relocating the existing overhead electrical facilities underground.

While the Floyd's project prompted this discussion, the issue extends beyond this individual development. Similar circumstances may arise on future commercial, industrial, residential, and other development projects where existing overhead utility infrastructure is located along a project frontage or perimeter. The continued application of Section 10.380 determines whether these improvements are completed as part of private development or whether existing overhead infrastructure remains in place until another funding source becomes available.

If undergrounding is not required as part of new development, opportunities to complete these improvements in conjunction with other site and frontage improvements may be lost. Any future undergrounding of the remaining overhead facilities could require separate coordination with the utility provider and identification of an alternative funding source and will likely become the responsibility of the City.

Staff is therefore bringing this matter before the City Council for discussion and direction regarding the continued application of Section 10.380 to new development projects throughout the City. Council direction will assist staff in determining whether to continue implementing the existing underground utility requirements or evaluate potential modifications to the ordinance for future consideration.

FISCAL IMPACT
There is no immediate fiscal impact to the City associated with receiving direction from the City Council regarding the continued application of Section 10.380 of the Zoning Ordinance.

Under the current ordinance, developers and property owners are responsible for the costs associated with undergrounding applicable utility facilities in conjunction with new development. If the City Council directs staff to evaluate modifications to these requirements, future development projects may no longer be responsible for some or all of these improvements, depending on the nature of any subsequent ordinance amendments.

Any undergrounding improvements not completed as part of private development will likely require alternative funding sources if the City elects to pursue these improvements in the future. The potential fiscal impacts associated with any modifications to the ordinance would be evaluated as part of a subsequent Council action.

CEQA ANALYSIS
The proposed action is not a “project” as defined by Section 15378(b)(5) of the California Environmental Quality Act (CEQA) Guidelines because it involves discussion

DISCUSSION AND DIRECTION REGARDING THE APPLICATION OF UNDERGROUND UTILITY REQUIREMENTS UNDER ZONING ORDINANCE SECTION 10.380 - 3 -
and direction regarding the continued application of existing underground utility requirements under Section 10.380 of the City of Shafter Zoning Ordinance. The action is an organizational or administrative activity that will not result in direct or indirect physical changes to the environment and is therefore not subject to CEQA.

APPROVED BY THE CITY ATTORNEY

ATTACHMENTS

1. Undergrounding Electrical Lines-Zoning Ordinance

2. Undergrounding Utilities-Sub-Division Ordinance

3. Presentation Slides - Lerdo Highway Installation Examples

CHAPTER 10 CITY OF SHAFTER DEVELOPMENT CODE
General Development Standards 10-52

3. Passenger Loading Facilities
All new non-residential and multiple-family developments of 10 or more units with at least 100 parking spaces shall provide a minimum of one (1) passenger loading area equivalent to five (5) parking spaces in close proximity to the building entrances and located to avoid interference with on-site vehicle circulation.

4. Vanpool Parking Facilities
All new non-residential developments with a minimum of one-hundred (100) spaces shall provide preferential vanpool parking facilities for a minimum of one (1) space which has a minimum vertical clearance of nine (9) feet for each one-hundred (100) parking spaces.

5. Transit Improvements
All new non-residential and multiple-family developments, along existing or planned transit routes, shall provide transit improvements such as bus pullouts, bus pads, and bus shelters if determined necessary in consultation with DialA-Ride, or other locally operated transit systems.

6. Reduced Parking Requirements
Provisions shall be made by the Planning Commission for reduction of on-site parking space requirements for all new non-residential developments on a case by case basis when such developments are linked to other actions which reduce vehicle trips.

7. Country Wide Bicycle Plan
The City shall consider participation in implementation of the Country Wide Bicycle Plan upon its adoption.

10.380 UNDERGROUND UTILITIES

1. Requirement for Underground Installation of Utility Lines All permits dealing with utility lines shall be consistent with all applicable State laws and regulations.

Except as provided in this Title, the following utility lines, existing and proposed shall be installed underground in conjunction with new development projects.

Said undergrounding of utility lines shall include, but not be limited to, all new electrical distribution lines, existing electrical distribution lines of 34,500 Volts (V) or less, telephone, street light service lines, cable television and similar service wires or cable which:
a. provide new service to the property being developed; b. are existing and located within the boundaries of the property being developed;
Zoning Ordinance Page 411 of 416
CITY OF SHAFTER DEVELOPMENT CODE CHAPTER 10
10-53 General Development Standards
c. are existing between the property line and the centerline of the peripheral streets of the property being developed; or
d. are along the project perimeter boundary.

2. Responsibility for Compliance
Arrangements, including payment of all costs, for undergrounding utility lines shall be made by the developer or owner of the property to be developed with the serving utility company(s). Undergrounding of utility lines and structures may be done by the developer, or owner, with permission from the serving utility.

3. Timing of Compliance
Undergrounding shall be completed:
a. prior to the inspection approval of related street improvements; or b. prior to building occupancy if no related street improvements are required.

4. General Exceptions
The following exceptions shall apply:
a. Temporary overhead utility lines including necessary service poles, wires, and cables may be permitted and installed to the satisfaction of the Building Official for the period during which authorized construction is continuing for which valid building permits have been issued. All temporary overhead utility lines shall be removed prior to the issuance of the Certificate of Occupancy.
b. Appurtenances and associated equipment including, but not limited to, surface-mounted transformers, pedestal-mounted terminal boxes and meter cabinets, and concealed ducts in a underground system, may be placed above ground and installed to the satisfaction of the City Engineer.
c. In established residential areas where overhead utility lines presently exist along or near lot lines and where an in-fill single family dwelling unit is being developed on a single lot, or where an in-fill two family or duplex dwelling unit is being developed on a single lot overhead utility lines may be permitted and installed to the satisfaction of the City Engineer.

5. Exceptions Approved by the City Engineer
The following further exceptions may apply, subject in each case to the specific written approval of the City Engineer, and then only on the basis of a formal request detailing the reasons therefor:

CHAPTER 10 CITY OF SHAFTER DEVELOPMENT CODE
General Development Standards 10-54
a. On developments consisting of three lots or less that do not in total exceed one hundred and fifty feet (150') of frontage for residential, commercial, office professional, business park, public/institutional, or industrial development, the City Engineer may waive construction of underground utility lines along the peripheral streets or property lines, however, all on site utility service lines shall be installed underground.

In such a situation, the developer or property owner shall deposit the cost, as determined by the City Engineer, for undergrounding utility lines along the peripheral streets or property lines with the City for future undergrounding work to be done by the City.
b. A new single family residence constructed in rural undeveloped areas where there are no existing utility lines within a quarter (¼) mile radius.

However, in such a situation, the developer or property owner shall deposit the cost as determined by the City Engineer for undergrounding utility lines along the peripheral streets or property lines with the City for future undergrounding work to be done by the City.

6. Nonconforming Structures
Buildings and structures which, on the effective date of this Title or any subsequent amendments thereto, are nonconforming in regard to above ground on-site utility lines and structures, may continue to be used, altered or enlarged in the same manner, as if such nonconforming utility lines did not exist.

7. Appeals
An appeal, along with the appropriate fee, may be submitted to the City Council for the consideration of waiving all or portions of the requirements of this Section due to topographic conditions, soil or other factors that render undergrounding unreasonable or impractical. All appeals shall be in writing, and shall state the reason why undergrounding is unreasonable or impractical.

Appeals shall include a preliminary estimate of cost, in writing, from the serving utility company(s).

10.390 WATER EFFICIENT LANDSCAPE REQUIREMENTS

1. Purpose and Intent
Water is an increasingly limited and costly resource. It is the intent of this Section to establish a water conservation plan to reduce water consumption in the landscape environment. Pursuant to AB 325, the City has set the goal of implementing measures resulting in the more efficient use of water through landscaping and irrigation design. This may be achieved through the use of drought tolerant material, reduced turf areas and various irrigation technologies. Public and private landscaping projects shall adhere to the goal of water efficiency with limited exception.

City of Shafter Title 16 Subdivisions 12/20/2016 Page 52 proximity thereto, and if such name is appropriate for a street name, such name shall be approved. When any such street or way forms a portion of any proposed street or way ordered by the Decision Making Body to be surveyed, opened, widened or improved, and in such order a name therefore is assigned or designated, the name of such street or way shown on the map shall be the same as the name contained in said order

8.140 EASEMENTS
A. All utility distribution facilities (including but not limited to electric, communication, cable television lines, and other wires or cables for transmission or distribution purposes) installed in and for the purpose of supplying service to any residential or commercial subdivision shall be placed underground, except as follows:

1. Industrial subdivisions located within an “Industrial” (I) zone district.

2. Undergrounding of existing utility lines is not required along easements at the rear of lots of residential or commercial subdivisions where said easements do not face streets, roads, or highways.

3. Undergrounding of existing utility lines is not required within a landscaped area between an arterial or collector street right-of-way and a masonry wall that is or would be erected at the rear of all lots adjacent to such an arterial street right-ofway, provided there is adequate space to integrate existing, or relocated poles within said landscaped area, and said landscaped area is approved by the Decision Making Body.

4. Equipment appurtenant to underground facilities, such as surface mounted transformers, pedestal mounted terminal boxes and meter cabinets, and concealed ducts.

The subdivider is responsible for complying with the requirements of this subsection, and shall make the necessary arrangements with the utility companies involved for the installation of said facilities. The Decision Making Body may waive the requirements of this subsection if topographical, soil, or any other physical constraints make underground installation of said facilities unreasonable or impractical.

B. The sidelines of all easements shall be shown by fine dotted lines. If any easement already of record cannot be definitely located, a statement of its existence, nature, and recorded reference must appear on the title sheet. Distances and bearing on the sidelines of lots which are cut by an easement must be arrowed or so shown so that the map will indicate clearly the actual lengths of the lot lines. The widths of all easements and sufficient ties thereto to definitely locate the same with respect to the subdivision must be shown. All easements must be clearly labeled and identified; if an easement shown on the map is already of record, its recorded reference must be given. If an easement is being dedicated by the map, it shall be set out in the owner’s certificate of dedication. All notes and figures pertaining to easements shall be considerably smaller and lighter than those relating to the subdivision itself.

C. The City may require the subdivider to remove any trees, brush, or other obstructions lying within an easement or right-of-way. The subdivider shall be required to remove or trim trees or brush lying within the easements or rights-of-way over which utilities are to be constructed, when such trees or brush interfere with the construction of such utility lines. Such work shall be completed in a manner satisfactory to the City Engineer.

Underground Utilities

Overhead Utilities