Embodied Carbon Policy Reduction Calculator

About

A growing number of cities are committed to tackling the urgent challenge of their built environment carbon footprint through their policies and programs. 110 cities took the Cities Race to Zero Clean Construction pledges to reduce embodied emissions in their policies and programmes in 2021, and 40 leading cities are participating in the C40 Clean Construction programme and mayors are setting the direction of travel by signing the Clean Construction Declaration, which requires collective action to halve embodied emissions by 2030. 

However, embodied carbon is a new policy area for many cities and the lack of city-level data on embodied carbon is a significant barrier for policymakers to gain political support and make informed decisions. The goal of developing an embodied carbon policy reduction calculator is to address these challenges by:

• Modeling the potential embodied carbon reduction of a selected number of policies to give cities the values they need to make informed decisions;
• Allowing for comparison of emissions reduction policies for embodied carbon by key target dates (2030 and 2050) to assess the largest opportunities for impact; 
• Evaluating which policies may be required to meet embodied carbon reduction targets, such as those set by city or regional climate action plans; and
• Ultimately enabling cities to make the case for and adopt policies to reduce embodied carbon.

Proof-of-Concept Study

The Carbon Leadership Forum and C40 Clean Construction teams collaborated in 2021 to develop a proof-of-concept for an embodied carbon policy reduction calculator, described in this report. The goal of this study was to:

• Assess the availability of city data and life cycle assessment data required to develop a successful tool;
• Assess tool scope and functionality required to support cities’ needs; and
• Demonstrate the tool concept to pilot cities to determine if it would be useful in policymaking.

The team developed four prototype calculators to estimate emissions from four types of embodied carbon policies using urban growth projections (floor area, building type, etc.) to 2050. The calculators provide a baseline estimate of embodied carbon emissions by 2050 alongside the carbon savings potentials of the selected reduction targets and policies.

The calculators described in this report are proof-of-concept: they are still limited in their ability for comparative decision-making at this time due to the gaps in data identified through this initial phase. Appendix B lists the priorities identified by the authors, contributors, and pilot cities necessary for their future development.

Authors

The research team from the Carbon Leadership Forum at the University of Washington College of Built Environments:

• Brad Benke, Researcher, Carbon Leadership Forum
• Meghan Lewis, Senior Researcher, Carbon Leadership Forum
• Stephanie Carlisle, Senior Researcher, Carbon Leadership Forum
• Monica Huang, Researcher, Carbon Leadership Forum
• Kate Simonen, Executive Director, Carbon Leadership Forum

Author contributions: M.L., S.C., and K.S. led conceptualization; B.B., M.L., and S.C. conducted research and analysis; B.B. created the calculators; B.B., M.L., S.C., M.H., and K.S. performed review and editing; B.B. created the graphics; B.B. and M.L. wrote the paper.

Acknowledgments

This study was commissioned by and co-developed with C40, thanks to the support of the City of Oslo and Ingka Retail (Ingka Group). The work is independent and has not been commissioned by any business, government, or other institutions. We would like to thank the following individuals from the pilot cities for contributing their time and feedback:

• Ross MacWhinney and Julia Casagrande with the New York City Mayor’s Office of Climate and Environmental Justice;
• Kyle Diesner and Shawn Wood with the City of Portland; 
• Phoebe Romero, Marc Coudert, and Phillip Duran with the City of Austin; and 
• Sarah Talkington, Greg Arcangelie, and Martin Torres with Austin Energy Green Building.

We would like to thank EskewDumezRipple (EDR), GGLO, Kieran Timberlake, LMN Architects, Miller Hull, and Mithun for contributing LCA reference models and time to provide the collection of reference models that informed our research.