Low-Carbon Concrete
Ordinance
April 23rd, 2024
Peter Roquemore
Sustainability Analyst
Office of Sustainability & the Environment
What Is Low-Carbon Concrete?
Low-carbon concrete is a concrete mix that has the same strength properties of a traditional concrete mix but uses less Portland Cement and replaces it with lower-carbon alternatives.
Making cement generates 60% of concrete emissions. The goal is to replace some of the cement with lower carbon alternatives.
Traditional Concrete Mix:
• Portland Cement
• Water
• Gravel or Sand
Low-Carbon Concrete Inputs:
• Fly-Ash
• Slag
• Silica fume
• Natural Pozzolans
• Portland Cement
• Water
• Gravel or Sand
Low-Carbon Concrete Impact
Current Santa Monica green building policies address operational emissions, not embodied carbon.
Embodied Carbon are the emissions that occur from materials and the construction process.
Existing local policies and programs:
• Green Building Reach Codes
• Clean Power Alliance
• EV Charger Reach Code
• Electrify Santa Monica Rebate Program
• Building Performance Standards (under development)
Why Low-Carbon Concrete?
Climate Impact
• 14% - 33% reduction in emissions from standard concrete design.
No-to-Low Anticipated Cost Premium; Potential Savings
Industry and Policy Readiness
• Local suppliers support the proposed ordinance
• SB 596: Concrete industry is reducing emissions by 30% by 2045 • New state standard for embodied carbon in the 2022 CALGreen Intervening Code Ready to Implement
• Public Works has begun using low-carbon concrete.
• Low-carbon concrete is available today
Cost of Low-Carbon Concrete
DOE – Pathways to Commercial Liftoff: Low-Carbon Cement, September 2023 Moongate Pilot 43% Portland Cement
67% Slag & Fly-ash.
Low-Carbon Concrete Buildings
.
One World Trade Center
• Replaced 71% of
Portland Cement
Wilshire Grand Center
• Foundation used a
25% fly-ash lowcarbon concrete mix.
Low-Carbon Concrete Policies
2024 Update to the California Green Building Code
Marin County
City of Palo Alto
New York New Jersey Port Authority
Federal Government General Services Administration
Outreach and Policy Development
Peer Government Outreach
• OSE staff have learned from staff in Marin County, Palo Alto, and at the NY NJ Port Authority. • Including a meeting with Building Officials from Marin County, Palo Alto, and City of Santa Monica.
Commission of Sustainability, Environmental Justice, and the Environment • Motioned to support the proposed Low-Carbon Concrete Ordinance on January 22, 2024.
Stakeholder Outreach
• OSE staff met with affordable housing developer Community Corp. of Santa Monica. • OSE held a stakeholder engagement meeting for designers, architects, developers, green building experts, and building managers.
Industry Outreach
• California Nevada Cement Association provided a training to City staff on low-carbon concrete. • OSE staff met with major concrete suppliers in Santa Monica.
Low-Carbon Concrete Ordinance Summary
Adopt and Amend CALGreen 2024 Embodied Carbon Intervening Code • Section 5.409.3 Product GWP compliance – prescriptive path of the California Green Building Standards Code
Create Section 8.106.130 Reduction in Cement in SMMC Green Building Code • Requires all new construction, swimming pools, and spas to comply • Local Cement & Global Warming Potential Limits
• Includes allowable increases and exemptions
• Details compliance and verification steps
Local Reach Code Impact
CALGreen Embodied Carbon Standards:
• Non-Residential Buildings 100,000 sq ft or larger
• Schools 50,000 sq ft or larger
Santa Monica’s Local Reach Code Improves Upon CALGreen Standards by:
• Applying low-carbon concrete to all new construction (both residential and nonresidential) of all sizes, swimming pools, and spas. • Except projects submitted over the counter.
• Local Cement & Global Warming Potential Limits
• Embodied carbon limits are 43% lower than CALGreen mandatory limits. • Includes an additional compliance pathway that is easier for smaller suppliers.
Compliance Table These limits should result in concrete mixes that reduce cement by 20% - 35% Comparing GWP Limits in State and Local Codes
200
300
400
500
600
700
800
900
2500 psi 3000 psi 4000 psi 5000 psi 6000 psi 8000+ psi
GWP kg CO2e per cubic meter
Comparison to CALGreen Intervening Code Cycle
CalGreen 2024
CalGreen Reach Code Tier 1
CalGreen Reach Code Tier 2
Santa Monica
Ordinance Exemptions
• There is a lack of commercially available material necessary to comply. Determined by notification from at least two local concrete suppliers. • The cost of low-carbon concrete is more than a traditional Portland cement mix.
Determined by quotes from at least two local concrete suppliers comparing a lowcarbon concrete compliant mix and an ordinary Portland cement mix. • Emergency purchases made in conformance with Section 2.24.240; • This requirement does not apply to pre-packaged proprietary concrete bags used for small quantities (less than 3 yards) or where there is an immediate need for on-site concrete mixing.
Compliance and Verification
Compliance Acknowledgement Form
• Submitted as part of plans during Plan Check.
Verification Form and Proof of Concrete
• Verification Form submitted before or during inspection. • Environmental Product Declarations or Mix Designs for Concrete mixes used. • Batch receipts from concrete supplier verifying the above mixes and amounts..
Recommended Action
Staff recommends that the City Council:
1. Introduce for first reading the attached ordinance that adopts the 2022 California Green Building Standards Code including the 2022 intervening code updates;
2. Adopt the attached resolution that provides findings of local climatic, geological, topographical, and environmental conditions as required to adopt Santa Monica local amendments to the 2022 California Green Building Standards Code;
3. Introduce for first reading the attached ordinance that adopts local amendments to the 2022 California Green Buildings Standards Code to support decreased emissions from concrete;
4. Direct the City Manager to file the adopted resolution and ordinance amending the Green Building Standards Code with the California Building Standards Commission following the second reading of the ordinance; and
5. Adopt a finding of categorical exemption pursuant to Section 15308 of the California Environmental Quality Act (CEQA) Guidelines.
Allowable Increases
• High Early Strength: Portland cement or GWP limits shown in
5.409.3.5 can be increased by 30% for concrete demonstrated in writing to the Building Official or City Engineer, for Public Works Projects, as requiring high early strength.
• Project Weighted Average: A weighted average of the maximum GWP or Cement Limit for all concrete mixes installed in the project shall be less than the weighted average maximum GWP or Cement Limit allowed per Table 5.409.3.