Calculation Methodology
In order to calculate a Home Energy Score, a qualified assessor must conduct a brief walk-through of the home and collect about 40 data points. The assessor then uses the U.S. Department of Energy's (DOE) Home Energy Scoring Tool—an online free software program—to estimate a home's energy use, convert that into a score and develop recommendations for energy improvements.
The score reflects the home's condition as an asset—that is, the calculation method holds a number of variables constant. For example, it assumes that the home is used by two adults and one child, and that the thermostat is set at specific levels at various points of the year. By holding these other variables constant, the Home Energy Score allows consumers to compare homes on an equal basis, putting aside homeowner behavior.
The Lawrence Berkeley National Laboratory (LBNL) developed the Home Energy Scoring Tool. Learn more by visiting LBNL's Web site.
Data Required to Calculate a Score
DOE requires an assessor to provide information about those home attributes that are most likely to affect a home's energy consumption. All data required to calculate the home energy score is listed in the Data Collection Sheet.
Energy Use and the 10 Point Scale Used for the Pilots
The Home Energy Scoring Tool estimates the likely energy consumption of a home and then converts that into a score. Each point on the 10 point scale corresponds to a different energy consumption level. Homes that are expected to use the least amount of energy score a 10 and homes that are expected to use the most amount of energy score 1.
In addition, the energy range underlying the scale varies from region to region to account for differences in climate. For example, given that a home in Minneapolis is likely to use more energy than a home in a temperate climate such as San Diego, the points on the scale correspond to much higher energy values in Minneapolis than they do in San Diego. To score an 8, a home in Minneapolis can use up to 163 Million British Thermal Units (MBTUs); whereas, a home in San Diego can only use up to 133 MBTUs.
See how energy levels translate into points on the scale in each of the 19 regions by viewing Home Energy Score—Energy Usage Points.
Learn More About the Energy Software Used to Calculate the Score
The Home Energy Scoring Tool was developed by Lawrence Berkeley National Laboratory in collaboration with the U.S. Department of Energy. To learn more about the algorithms and assumptions used in that tool, visit the Google Site with the engineering documentation.