More than 75% of California's existing homes and commercial buildings were built before the Building Energy Efficiency Standards were developed in 1978. Existing buildings provide a significant opportunity to reduce overall energy use, save money, improve air quality, and cut greenhouse gas (GHG) emissions. Strategies to improve energy efficiency, maximize use of clean energy, optimize demand flexibility, and accelerate building electrification provide pathways achieve California’s near-term and long-term climate and air quality goals while saving money over time.
Energy efficient technologies and practices help to minimize energy consumption. The California 2019 Energy Efficiency Action Plan serves as the state's policy map for improving, increasing, and targeting energy efficiency. In order to meet California’s energy efficiency goals, improved financing options and availability, increased program participation, improved code compliance, and increased equipment turnover is necessary.
Maximize Use of Clean Energy
By 2030, renewable energy resources must supply 60 percent of total retail sales of electricity. By 2045, a combination of renewable energy resources and zero-carbon resources must supply 100 percent of retail sales of electricity. California’s clean energy grid of the future supplied mainly with intermittent solar photovoltaics (PV) and wind energy makes it important to consider when to use energy. GHG emissions from electricity use in residential and commercial buildings are lowest during the daytime when solar energy is in full supply or in the middle of the night when there is excess wind energy on the grid. Energy Upgrade California provides an interactive page on time-of-use to maximize renewable energy consumption.
Energy Demand Flexibility
Buildings of the future should match renewable supply with buildings dynamic end uses and/or store on-site renewable energy generated until needed for those end uses. For example, heat pumps for water and space heating can be thermal batteries to help match the timing of electricity demand to the generation of renewable energy. Energy storage as well as automation of lighting, pumps and compressors, electric vehicles, and other appliances can help to optimize the time of use for grid-based electricity and/or on-site renewables.
By electrifying heating, ventilation, and air conditioning (HVAC) and water heating systems in existing homes, bill savings can be up to $750 per year in single family homes and up to $300 per year in low-rise multifamily buildings. Retrofitting existing residential buildings with electric end uses has the potential to reduce GHG emissions by about 30-60% compared to mixed-fuel homes.
Health Benefits of Building Electrification
About 10 percent of GHG emissions are due to natural gas use in buildings, which also produces carbon monoxide, nitrogen oxides, ultrafine particles, and other toxic air contaminants. Gas appliances have been linked to various acute and chronic health effects, including respiratory illness, cardiovascular disease, and premature death. In addition to reducing GHG emissions and outdoor air pollution, building electrification improves indoor air quality and provides significant health benefits. If all residential gas appliances in California were immediately replaced with clean electric alternatives, the reduction of outdoor NOx and PM2.5 would result in hundreds fewer deaths and cases of acute and chronic bronchitis annually. These health benefits are equivalent to approximately $3.5 billion in monetized savings over the course of one year.
 Mahone, A., Li, C., Subin, Z., Sontag, M., Mantegna, G. (2019). Residential Building Electrification in California: Consumer economics, greenhouse gases, and grid impacts. Energy and Environmental Economics, Inc.
California Air Resources Board. 2019. California Greenhouse Gas Emission Inventory: 2000 – 2017, 2019 Edition, California Air Resources Board.
 Zhu, Y., Connolly, R., Lin, Y., Mathews, T., Wang, Z. (2020). Effects of Residential Gas Appliances on Indoor and Outdoor Air Quality and Public Health in California. UCLA Fielding School of Public Health.