The Home Energy Rating System (HERS) Index The HERS Index was developed by the Residential Energy Services Network, a network founded by the National Association of State Energy Officials and Energy Rated Homes of America (RESNET 2012). The HERS program uses on-site home assessments to determine energy retrofit needs, including a blower-door test, air duct tests, insulation inspection, wall-to-window ration calculation, determination of solar orientation, and HVAC efficiency tests. The data is then entered into an analytical software tool that projects home energy use. The Index itself is a scale of 0 to 150, with higher numbers indicating more energy use. As the defining reference point, a home built to 2004 International Energy Conservation Code will score a 100 (RESNET 2012). Every point below 100 indicates that the home being examined is 1% more efficient than the reference home. At a score of zero, the home in question is a net zero energy building, i.e. 100% more efficient than the reference home. For new homes, limited information from the building’s plans can be used to develop a preconstruction HERS Index, from which builders or architects can work to improve the planned energy efficiency (RESNET 2012). As such, it can be used for new/unbuilt homes as well as existing ones. HERS can be used for all single-family homes and multifamily buildings under three stories. The resulting certificate lists the home’s energy attributes, provides the actual rating, and estimates the annual energy costs (CEC 2011). The U.S. Department of Energy is currently conducting a nationwide contest for homebuilders, inviting them to rate their new homes with HERS ratings and display this rating to new residents (DOE 2012a).
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