In 2014, the U.S. Department of Energy (DOE) issued a FOA (Funding Opportunity Announcement) to conduct residential energy code field studies using a radically different methodology from previous studies. Historically, studies defined and measured “compliance” as the portion of all code requirements being met on a house-by-house basis. Compliance was assumed to be a surrogate for energy, but that connection was never empirically established. Low compliance rates reported by many past studies resulted in the widespread belief that large potential energy savings were available from improving code compliance.

DOE’s new methodology focuses directly on energy impacts. A preliminary analysis identified key code requirements accounting for a large majority of the energy used in the new single-family homes which comprised the study population. State-level sampling plans ensured statistically representative samples of each of these requirements were obtained.

For each state, energy use intensities (EUI’s) were calculated for a home just meeting the state prescriptive code requirements and compared to an EUI representing the collected field data. Results suggest that, on average, energy codes deliver most or all expected energy savings for the code adopted in a given state, overall—the opposite of conventional wisdom. At the same time, many sampled homes failed to meet at least one key code requirement, and many of the non-key requirements were not met. Also, the adopted code varied by state so there is clearly more energy savings potential available from adopting new codes. This rich new data set will drive important discussions on the value and role of energy codes.