Field Assessment of Energy Audit Tools for Retrofit Programs
This project focused on the use of home energy ratings as a tool to promote energy retrofits in existing homes. A home energy rating provides a quantitative appraisal of a home’s energy performance, usually compared to a benchmark such as the average energy use of similar homes in the same region. Home rating systems can help motivate homeowners in several ways. Rating systems based on energy performance models, the focus of this report, can establish a home’s achievable energy efficiency potential and provide a quantitative assessment of energy savings after retrofits are completed, although their accuracy needs to be verified by actual measurement or billing data. Ratings can also show homeowners where they stand compared to their neighbors, thus creating social pressure to conform to or surpass others.
This project field-tested three different building performance models of varying complexity, in order to assess their value as rating systems in the context of a residential retrofit program. The major focus was the Home Energy Score, which was under development by the U.S. Department of Energy (DOE) at the time of this project. It is designed to give a complete home performance assessment while simplifying the building measurements to 36–67 data inputs, depending on a home’s configuration. The Center for Energy and Environment (CEE) was one of nine national pilot sites in the spring of 2011, and tested the Home Energy Score on 154 Minnesota homes. The goal of these pilots was to provide feedback to the DOE about technician experience, homeowner reaction, and the pattern of scores in a given region of the country, so that DOE could make necessary changes before the national launch of the tool. Numerous changes have been made to the national version, launched in June 2012, including adjustments for several issues raised though this analysis.