Investments in Low-Carbon Living focused on Operational and Embodied Carbon

The United States is currently experiencing a significant shortage of housing, with projections indicating that roughly 20 million new residential units will be required in the coming decade. Given the urgent need to accelerate decarbonization, it is critical to address energy and carbon emissions in both new and existing multifamily buildings. However, older housing units are often inefficient, while new multifamily constructions in the U.S. are way behind in terms of codes and accomplishments. Despite the emphasis on reducing operational carbon emissions, embodied carbon emissions have largely been overlooked because of the challenges associated with quantifying them and their indirect impact on occupants. This study contends that both types of carbon emissions must be considered together to accurately measure total carbon emissions and presents Low-Carbon Living scenarios that compare the impacts of three alternatives: Deep Retrofit, Passive New, and Adaptive Reuse. Through a database of case studies with actual energy use data, this study identifies and prioritizes better investments based on their contribution to energy efficiency improvements. The Carbon Avoided Retrofit Estimator (CARE) Tool from Architecture 2030 is used to evaluate the three progressive scenarios based on the highlighted actions, while sensitivity analyses are used to determine the length of the time to assess total carbon trade-offs. As a result, this study aims to prioritize decarbonizing actions and compare the estimated total emission savings from the multifamily alternatives from both short-term and long-term perspectives. The findings of this research will inform the development of building performance standards aimed at achieving net zero emissions and will be applied to specific locations to optimize the benefits of Low-Carbon Living.