The Climate Policy Initiative San Francisco has published Codes to Cleaner Buildings: Effectiveness of U.S. Building Energy Code,
which reports on the results of the first U.S. study to measure impact of state energy codes using residential energy use data at the state level. The authors conducted regression analysis that compared states with building energy codes to those without and measured the realized energy savings of energy codes and compared them to the modeled estimates.
The study found that building energy codes are associated with lower energy consumption per housing unit; a shift toward natural gas and away from 'other' fuels, mostly notably fuel oil; and lower emissions per housing unit.
The report states that "residential buildings consume 22% of U.S. primary energy use and produce 21% of U.S. carbon dioxide emissions, so the ultimate potential impact of building energy codes is substantial." Most states have adopted Department of Energy (DOE)-recommended model codes, first set in 1992 and subsequently updated several times; others have written their own standards. Seven U.S. states - Alabama, Mississippi, Missouri, North Dakota, Oklahoma, South Dakota, and Wyoming - do not have mandatory building energy codes. Other states such as New Mexico and Maine are considering reverting to less stringent codes. CPI's analysis, which reviewed states' energy use from 1986 to 2008, found that states adopting federal codes have achieved an approximately 10% reduction in household energy use, and a 16% reduction in household greenhouse gas emissions.
"Engineering models suggest that U.S. building codes should deliver energy savings; we now have solid evidence that they do," said Kath Rowley, director of Climate Policy Initiative's San Francisco office. "States looking for ways to reduce energy use should take note."