City Manager’s Office
DATE: April 29, 2025
TO: Council Sustainability Committee
FROM: Grace Kann, Climate Fellow
Remy Rinn, Climate Fellow
Denise Lin, Sustainability Analyst II
VIA: Danielle Lee, Chief Sustainability and Resiliency Officer Audrey Seymour Ramberg, Assistant City Manager
SUBJECT: 2023 Community Greenhouse Gas Emissions Inventory
RECOMMENDATION
Review and accept the 2023 Community Greenhouse Gas Emissions Inventory and recommend acceptance by the City Council.
BACKGROUND
The most recent climate goal adopted by the City Council was on April 21, 2020 to become a carbon-neutral city by 2045. Every year, staff provides an update on the community’s progress in reducing greenhouse gas (GHG) emissions to the Council Sustainability Committee ( CSC). If accepted by the CSC, the report is then forwarded to the City Council for review and acceptance.
On June 25, 2024 , the City Council accepted the final 2021 and preliminary 2022 community greenhouse gas inventories. This year , staff is transitioning to bringing a single -year final inventory for 2023 rather than a staggered preliminary and final inventory for two separate years.
The final 2022 results have been incorporated in to the year-by-year comparison graphs in the Analysis section of this report.
In response to the growing threat of climate change over the last few years , the CSC has expressed continued interest to accelerate the City’s climate goal s, which resulted in the City Council authorizing a scope of work and contract on November 19, 2024 to develop a technical analysis of two decarbonization target years, 2035 and 2040. The project is currently under way, and the GHG emission information in this report will support the decarbonization analysis. Staff will be presenting project updates as well as seeking feedback and direction from the CSC on elements of the analysis in June.
2023 Community Greenhouse Gas Emissions Inventory
April 29, 2025
Staff also presents a municipal GHG inventory every three to five years , with the last report presented in 2022. Another inventory will be completed by 2027 to reflect progress from upcoming City projects, such as fleet and equipment electrification and installation of solar arrays and battery energy storage system projects.
ANALYSIS
A communitywide GHG inventory measures sources of local GHG emissions from residential and commercial activities, which are typically from:
• Building energy use (electricity and natural gas), including electric vehicle charging;
• Fossil fuel-powered vehicle use (e.g., gasoline and diesel);
• Off-road equipment (e.g., construction, industrial, and gardening equipment);
• Energy used to transport and treat water; and
• Waste produced by the community and emissions from the closed Shoreline Landfill.
The inventory does not capture all local emissions related to the community, such as emissions from food, air travel, or manufacturing goods, because they are difficult to measure. It also does not capture all the impacts of local GHG -reduction policies or programs , such as plant -based eating and tree -planting programs. The reductions from implementation of various Mountain View transportation policies and programs are also challenging to capture in a GHG inventory that uses aggregated and modeling data to assess emissions. See Attachment 1 for how data is used to measure GHG emissions for the community. To address Council and community interest in this additional information , staff will begin to report on progress and achievements made in Mountain View that relate to the GHG emissions reductions from residential and commercial activities. In addition, the decarbonization analysis for 2035 and 2040 that is under way will explore how to incorporate Mountain View policies and programs that reduce emissions into future GHG inventories.
2023 Community Greenhouse Gas Emissions Inventory Results
The inventory represents a rough estimate that is subject to change as better data and methodologies become available. Year-by-year comparisons can be misleading as external factors may influence the increase or decrease of emissions in any given year, such as economic booms/recessions or a pandemic. Viewing GHG emission trends over time is useful in providing a general understanding on how policies, programs, and technologies are reducing emissions.
2023 Community Greenhouse Gas Emissions Inventory
April 29, 2025
Given that the City Council adopted a goal to be carbon -neutral by 2045 and to accurately view trends over time , a rolling five-year average of past inventories to compare the most recent inventory will be used to gauge community emission reductions. While this rolling average will typically be collected over five years, with community inventories conducted on an annual basis, there is currently inadequate sequential data to make this possible for the 2023 Inventory. This is due to lacking sufficient 2016 data and 2020 to 2022 being anomalies due to the pandemic.
Thus, the 2023 GHG emissions inventory will use a four-year rolling average (2015, 2017, 2018, and 2019) as the primary basis of comparison in this report. Future inventories will include a five- year rolling average, continuing to exclude the pandemic years of 2020, 2021, and 2022.
Table 1 provides the 2023 GHG emissions and compares them to the rolling average baseline (2015, 2017, 2018, 2019) of the four most recent inventories , excluding 2020, 2021, and 2022 .
The City is on a path toward decarbonization with 2023 emissions 32% below the rolling average baseline. Individual sectors such as water, building electricity, and transportation have made notable reductions due to state policies and City actions described in the respective sections below. Figure 1 provides a year-by-year comparison, in which it can be seen that 2023 emissions are higher than the three years (2020, 2021, and 2022) in which emission reductions were driven by pandemic conditions.
Table 1: Results of the 2023 Community GHG Inventory
Rolling Average Baseline
(2015, 2017, 2018, 2019)
Emissions (MT CO2e)1
2023 Total Emissions
(MT CO2e)
Percent Below
2015-2019 Rolling
Average
Annual Emissions 672,947
509,660
32%
Individual Inventory Sectors
On-Road
Transportation
422,009 293,538
44%
Building Natural
Gas
113,257
111,495
2%
Building
Electricity
76,558
51,862
48%
Off-Road
Transportation
41,076
39,548
4%
Waste
17,642
12,484
41%
Water
2,406
732
229%
1 MT CO2e stands for metric tons of carbon dioxide equivalent. It is a metric used to standardize the measurement of greenhouse gas emissions and provides a common unit that allows different gases, such as methane (CH 4) and nitrous oxide (N2O), to be compared based on their global warming potential. 2023 Community Greenhouse Gas Emissions Inventory
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Figure 1: Community GHG Emissions 2015 through 2023
Figure 2 shows a breakdown of 2023 emissions by sector. Transportation and natural gas used in buildings are the two largest emissions sources and account for 80% of the City’s emissions.
Figure 2: 2023 Emissions by Sector
The inventory methodology and data sources are detailed in Attachment 1.
Trends and Insights for Each Emission Source
Each sector of the community GHG inventory in Figure 2 above has trends that are notable and provide insights on how Mountain View can influence the reduction of emissions. The following sections provide details on the emissions trends in each sector.
2023 Community Greenhouse Gas Emissions Inventory
April 29, 2025
Transportation
Although transportation emissions have declined, g asoline-powered passenger vehicles and light-duty trucks still continue to generate most of the City’s emissions (over 50%), as shown in Figure 3. The City can further reduce these emissions by continuing to support transit -oriented development, municipal fleet electrification, neighborhood walkability, travel by nonvehicular modes, remote work efforts, and the transition to zero-emission vehicles for residents. Staff will present a multi-family electric vehicle (EV) charging gap analysis to the CSC this year to support efforts to reduce emissions associated with transportation. These strategies can also contribute to other community benefits, such as i mproved air quality, safer streets, a vibrant downtown, and improved public health. Staff also monitors other transportation trends, including travel modes and electric vehicle adoption. Staff is also supporting development of the Citywide Transportation Demand Management ( TDM) Ordinance that seeks to reduce single -occupancy vehicle trips and increase use of multi-modal transportation options.
Vehicle emissions dropped by 44% from the four-year rolling average, driven by higher fuel - efficiency standards, higher gasoline prices, and more EVs, e-bikes, and e-scooters. Daily per- capita vehicle miles traveled (VMT) ha s also decreased from the four-year rolling average of
18.4 miles to 14.8 miles in 2023. It should be noted that daily per -capita VMT has increased post-COVID (for example, from 12.1 in 2022 to 14.8 in 2023). Staff will continue to monitor VMT values in comparison to the rolling average.
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* The “Other” category i ncludes emissions from On-Road Medium -/Heavy-Duty—CNG/LNG, On -Road Passenger/Light-Duty—Diesel, and Caltrain Diesel ONLY in 2022 and 2023.
Figure 3: Transportation Emissions by Vehicle and Fuel Type, 2015 through 2023
U.S. Census data shows that the percentage of residents driving alone to work largely declined from 2015 to 2022, mainly due to increased remote work during the pandemic (Table 2) .
However, in 2023, this number rose by 11% compared to 2022 as some organizations required
2023 Community Greenhouse Gas Emissions Inventory
April 29, 2025
employees to return to the office. As the effects on the pandemic subside, it is likely there will be less fluctuation between in-person and remote work rates in the years following 2023.
Table 2: Commuting Characteristics of Mountain View Residents for 2015, 2022, and 2023
Means of Transportation
to Work 2015 2019 2022 2023
Drove alone 73.40% 63.90% 53.20% 65.80%
Carpooled 6.00% 8.80% 4.50% 5.70%
Public transportation 5.30% 8.60% 2.10% 3.90%
Walked 2.70% 4.50% 3.20% 1.70%
Bicycle 7.20% 7.90% 5.60% 3.90%
Taxicab, motorcycle, or
other means 1.90% 2.10% 1.20% 1.50%
Worked from home 3.40% 4.10% 30.20% 17.60%
TOTAL 100.00% 99.90%* 100.00% 100.10%*
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* U.S. Census Data S0801 does not add up to 100%.
California Air Resources Board (CARB) Advanced Clean Cars II regulations dictate that by 2035, all new cars, trucks , and SUVs sold in California will be zero -emission. Starting in 2026, t hese regulations will increasingly impose limits on how many vehicles powered by fossil fuels (gasoline and diesel) can be sold. At the same time, a ccording to data from the California Energy Commission, sales of new zero-emission vehicles in Mountain View continue to grow, as seen in Figure 4. This data includes sales made in 2024 as it is the most recent data available.
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* Based on data from ZIP Codes 94035, 94039, 94040, 94041, 94042, and 94043.
Figure 4: New Zero-Emission Vehicle Sales in Mountain View Zip Codes Per Year*
2023 Community Greenhouse Gas Emissions Inventory
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On a Countywide level, zero-emission vehicles made up 25% of all new light-duty vehicle sales in Santa Clara County in 2023 . The rise of increasing EV purchases can be attributed to many factors, such as increasing gasoline prices in California, availability of tax credits and incentives, and the expansion of EV charging infrastructure across the state. This leads to a decrease in the total cost of ownership for an EV as opposed to a conventional gas oline-powered car. This growth can be further supported by promoting and adopting EV/zero-emission vehicle rebate or incentive programs and expanding public and private charging infrastructure in Mountain View.
Building Energy
Low-emission electricity from Silicon Valley Clean Energy (SVCE) continues to drive the majority of Mountain View’s building energy sector emissions reductions , as shown in Figure 5. SVCE began providing low-carbon electricity to Mountain View in April 2017 and currently provides electricity to around 96% of residential and commercial customers in its service territory, previously served by PG&E.
SVCE has updated its energy portfolio over the years to meet electricity demand, which has led to an increase in the emissions associated with its electricity generation. Building energy sector emissions have risen slightly because of these changes, as well as from added customers due to new developments in Mountain View.
Over the past few years, th ese emissions increases were partially, but not completely, offset by emissions reductions due to the City’s Reach Codes . These Reach Codes regulated the design and construction of buildings and encouraged building electrification to take advantage of low- carbon electricity offered by SVCE.
With the transition of nearly all the community’s electricity accounts to SVCE starting in 2017, natural gas comprises the majority of energy -sector emissions. The City’s GHG -reduction strategy focuses on reducing natural gas use by encouraging electrification of space and water heating of commercial and residential buildings. In 2024, the City Council adopted low-cost prewire requirements for new buildings that would allow gas appliances to be easily replaced with an electric alternative in the future. In April, the City will be launching the Year of the Water Heater Campaign that includes providing heat pump water heater (HPWH) rebates to help residents electrify their homes.
Furthermore, the City will be exploring updated Reach Codes and zoning incentives to promote building electrification within the next year . However, the ability for the City to adopt Reach Codes will depend on whether Assembly Bill (AB) 306 is adopted by the state. If adopted, this bill would, from June 1, 2025 until June 1, 2031, prohibit a city or county from adopting reach codes that impact residential units to support more housing production . It would also pause state building code cycles for the same period . AB 306 passed the Assembly floor unanimously and 2023 Community Greenhouse Gas Emissions Inventory
April 29, 2025
will be voted on by the State Senate. The City has submitted a letter of opposition to AB 306 this month. Reach codes that were adopted and effective on January 1, 2025 could be readopted in the next building code cycle (2025), such as the City’s prewire requirements. Staff will work with SVCE to continue to explore other pathways outside of the Reach Code process to encourage building electrification.
Figure 5: Residential and Nonresidential Energy Emissions, 2015 through 2023
Off-Road Mobile Equipment
Figure 6 shows off-road mobile equipment emissions from construction, commercial, industrial, lawn and garden, portable, and other equipment that uses gasoline or diesel.
In the coming years, staff expects off-road emissions to decline due to CARB banning the sale and manufacturing of all carbon /pollutant-emitting landscape equipment in 2024. The City is also making efforts to decrease off-road emissions by using all electric equipment at parks and doing outreach at the Day Worker Center.
2023 Community Greenhouse Gas Emissions Inventory
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Figure 6: Off-Road Mobile Emissions, 2015 through 2023
Waste
Solid waste emissions are dependent on both the total amount of solid waste sent to landfills and the percentage of organic material in the waste stream. Organic material, such as yard trimmings, food scraps, and food-soiled paper, is the primary contributor of emissions from solid waste due to the release of methane as these materials decompose in a landfill.
In 2023, Mountain View implemented key policy updates to reduce landfill waste. The Food Service Ware Ordinance, effective January 1, required all disposable food ware to be either compostable through the City Organics program or fully recyclable aluminum. Additionally, food vendors were banned from providing straws, stir sticks, or toothpicks made from plastic, including compostable plastic. These policies play a role into the larger Zero Waste Plan that seeks to divert 90% of solid waste from landfills by 2030.
In 2024, through the Rethink Disposable Program, eight Mountain View businesses converted their dine-in food ware from disposable to reusable , and 27 businesses converted to -go food- ware to compostable fiber-based containers compliant with the City’s ordinance.
As shown in Figure 7, solid waste emissions have been dropping primarily because the amount of landfilled waste decreased.
2023 Community Greenhouse Gas Emissions Inventory
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Figure 7: Solid Waste Emissions, 2015 through 2023
Water and Wastewater
This sector includes emissions from the energy used to treat wastewater and extract, convey, treat, and transport potable water. In recent inventories, wastewater treatment has contributed to over 95% of emissions from the water sector. Emissions associated with potable water use remain low as the water supply for Mountain View is primarily gravity-fed and requires very little energy. Increased conservation efforts would reduce emissions from potable water use and wastewater treatment.
Figure 8 shows the estimated wastewater emissions from 2015 through 2023. Natural gas use at the Palo Alto Regional Water Quality Control Plant (Wastewater Treatment Plant) contributes to most of the wastewater emissions. While the City of Palo Alto purchases carbon offsets for its natural gas use, there are still emissions associated with the on -site combustion of natural gas since inventory calculation protocols do not consider offsets as reducing local emissions. In 2019, the incinerators at the Wa stewater Treatment Plant were decommissioned, decreasing natural gas use significantly. The Wastewater Treatment Plant transitioned to trucking biosolids off-site to processing facilities where they are converted into fertilizers and other beneficial products. As a result, emissions from wastewater treatment decreased by 55% between 2018 and 2019. In 2020, the first year that no biosolids were incinerated at the Wa stewater Treatment Plant, emissions from wastewater treatment dropped another 44%, and then remained similar in 2021 to 2023.
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Figure 8: Wastewater Emissions, 2015 through 2023
FISCAL IMPACT
There is no fiscal impact associated with accepting the 2023 Community GHG Emissions Inventory. However, the Inventory does inform where budget and resources may need to be spent to reduce emissions, such as the implementing the Year of the Water Heater Campaign and investment in zero-emission vehicle infrastructure.
CONCLUSION
The 2023 Inventory indicates the community is reducing emissions through local, regional, state, and federal programs and policies. The City will continue exploring ways to accelerate emissions reductions through the development of the decarbonization goal analysis for 2035 and 2040, anticipated to be complete by 2026. Market, state, and federal efforts will also be key to achieving Mountain View’s decarbonization goals.
GK-RR-DL/6/MGR
621-04-29-25M-1
Attachment: 1. Community Greenhouse Gas Emissions Inventory Methodology