What are the energy and greenhouse gas benefits of repurposing non-residential buildings into apartments?

Abstract

This study examines the potential strategies for reducing embodied energy and greenhouse gas emissions through adaptive reuse of non-residential buildings for residential purposes, as compared to new construction of apartment buildings. Such an approach can address housing crises in urban areas with an abundance of underutilized non-residential buildings, promoting sustainable housing growth. A comprehensive assessment of repurposing in California reveals approximately 510 million m² of floor space across 230,000 non-residential buildings in the current building stock. The potential reduction in embodied energy and CO2eq emissions ranges from 0.14 to 1.4 billion GJ and 5.0–70 million metric tons for the state, respectively, contingent upon the percentage of repurposed floor space (10–100%) and adaptive reuse scenario (retaining structural components and façade or solely the structure). A repurposed building avoids about 56% of embodied energy, 34-48% of CO2 eq emissions, and 72% of materials by mass compared to building a new apartment building. However, various technical, financial, and regulatory challenges may hinder emissions reductions, necessitating proactive policy measures. Cities can potentially expedite the process by streamlining approvals for mixed-use adaptive reuse projects involving both commercial and residential spaces.