Understanding Home Energy Ratings

The Res-Intel software uses building energy regression modeling to develop end use energy intensity metrics for each single family residence in a utility service territory.

The Home Energy Intensity (HIS) end-use intensity metric is based on the building “assets”: wall and window efficiency, the efficiency of the heating and cooling equipment, the number of occupants, as well as behavioral tendencies of the occupants.The Res-Intel targeted marketing recommendations are composed of the building assets plus the occupancy and behavioral factors. This aggregated, or operational, approach distinguishes Res-Intel’s HIS indicator from other rating schemes that are based on the building asset only, that assume “typical” occupancy and usage characteristics.

Use of Energy Efficient Utilities by House Age
Use of Energy Efficient Utilities by House Age – 2010 California Residential Appliance Saturation Survey

These rating schemes such as the Home Energy Rating Score (HERS) and the Home Energy Saver (HES) require detailed survey data on the building’s assets in order to develop intensity metrics. Asset ratings allow for more detailed comparisons of buildings while assuming “normal” occupancy and behavior across households. Asset ratings are also EXPENSIVE! HERS ratings cost a minimum of $500 to develop and their impact on homeowner conservation investments is limited.

Engineers and others who advocate for asset-based ratings assume that occupant behavior can’t be affected, or isn’t relevant. But of course, occupancy and behavioral factors are embedded in actual energy consumption, and interventions are available to reduce energy consumption for high occupancy households with high consumption.

Since the goal of Res-Intel is to overcome market failures about customer building information, the operational HIS indicator is required to begin to improve the cost effectiveness of utility DSM programs. We can’t wait around for detailed building data when so much good work can be done with basic real estate data!