Energy efficiency and cost benefits of office-to-residential building transformation: Insights from Los Angeles

To address office vacancy and housing shortages, adaptive transformations of office buildings into residential spaces are proposed. While renovating old office buildings is prioritized, energy and socio-economic feasibility assessments are lacking. This study fills the research gap by using building performance simulations to create over 500 models, revealing the potential benefits of converting office buildings to residential use through multi-scenario evaluations. The research examined twenty-three pre-1980 office buildings in Los Angeles County with vacancy rates over 50%, establishing a baseline scenario based on actual data. Four scenarios were compared: baseline scenario, office energy efficiency transformation scenario, office-to-residential transformation scenario, and office-to-residential and energy efficiency transformation scenario. The study evaluated energy consumption and costs for each scenario. The research found that functional transformations cut energy use intensity by 46.09% and Life Cycle Cost by 61.61%, saving at least 5,154.84 MWh annually for Los Angeles County. It also found a comprehensive approach that reduces electric equipment loads, improves insulation, and moderately cuts lighting power density offers the best energy and economic benefits. The study suggests prioritizing renovation for small to medium-sized old office buildings with energy consumption below 348.3 kWh/m 2 ·yr, footprint area over 2000 square meters, and height under 26 meters. This study highlights the benefits of functional transformation over energy-saving transformations in reducing operational energy and costs, offering decision-making methods and optimization recommendations for converting non-residential buildings to address the climate and housing crisis. • Evaluating the feasibility of residential transformation of old office buildings in terms of energy consumption and economic costs. • It is feasible to achieve net zero energy consumption in old office buildings through residential transformation. • Combining measures can each reduce energy consumption and life cycle costs by over 20%. • Prioritizing the residential transformation for low-energy, large-area, and low-height buildings in old, small to medium-sized office buildings.