The performance of buildings designed to meet current state energy codes is compared to their performance when meeting new editions of IECC design requirements to determine whether more stringent energy code editions are cost-effective in reducing energy consumption and life-cycle carbon emissions. states for study periods ranging from 1 year to 40 years. The results of this report are based on analysis of the Building Industry Reporting and Design for Sustainability (BIRDS) new residential database, which includes 9120 whole building energy simulations covering 10 building types in 228 cities across all U.S. This study considers the impacts that the adoption of newer, more stringent energy codes for residential buildings would have on building energy use, operational energy costs, building life-cycle costs, and “cradle-to-grave” life-cycle carbon emissions. Some states do not have a code requirement for energy efficiency, leaving it up to the locality or jurisdiction to set its own requirements. As of July 2014, states had adopted energy codes ranging across editions of the International Energy Conservation Code (IECC) (2003, 2006, 2009, and 2012). Energy efficiency requirements in energy codes for residential buildings vary across states, and many states have not yet adopted the latest energy efficiency code edition.
