Longer-Run Evidence on Whether Building Energy Codes Reduce Residential Energy Consumption

This paper provides an ex post evaluation of how changes to a building energy code affect energy consumption. Using residential billing data for electricity and natural gas over 11 years, the analysis is based on comparisons between residences constructed just before and just after a building code change in Florida. While an earlier study using 3 years of data for the same residences showed savings for both electricity and natural gas, new results show an enduring savings for natural gas only. These findings underscore the importance of accounting for all sources of energy consumption when conducting evaluations of building codes. More broadly, the results provide a counterpoint to the growing literature casting doubt on whether ex ante forecasts of energy efficiency policies and investments can provide useful information about actual energy savings. Indeed, more than a decade after Florida's energy code change, the measured energy savings still meets or exceeds the forecasted amount.