Home Energy Rating
An automobile's fuel efficiency can be measured by miles per gallon, but how is a home's energy efficiency measured? In 1995, the National Association of State Energy Officials and Energy Rated Homes of America founded the Residential Energy Services Network (RESNET) to develop a national standard for home energy rating systems and for evaluating energy efficient mortgages, which became the Home Energy Rating (HER) system.
Background
The HER scale is an objective measurement of a home's energy efficiency, based on a 150-point energy use scale where the energy efficiency of a standard new home is set at 100, while more efficient homes range downward from 100-0 and less-efficient homes range upward from 101-150. Lower numbers correlate with relatively more efficient homes. This scale can be applied to compare different homes to arrive at an estimate of their relative efficiency and their heating and cooling costs. The ratings are adjusted for different climates in various parts of the country and are normalized according to average household energy consumption in the region.
The HER calculation is prepared by trained technicians who attend RESNET's training program and pass the national test. The industry standard for HERS training includes a 40 hour course where students learn the basics of building science, proper use of duct and blower door equipment, RESNET standards, and mortgage and lending-related information.
RESNET's standards are recognized by the federal government for verification of building energy performance for programs such as federal tax incentives, the Environmental Protection Agency's ENERGY STAR program and the U.S. Department of Energy's Building America Program. RESNET standards are also recognized by the U.S. mortgage industry for calculating a building's energy performance into the mortgage loan. The HER rating can be used to help justify a mortgage loan because the building's owner will be spending less on heating and cooling, thus reducing the mortgage lender's risk exposure.
Objective Evaluations for both Old and New Homes
Home energy ratings can be used for either existing older homes or newly-constructed homes. A home energy rating of an existing home (referred to as a "confirmed rating") provides a homeowner with a report listing various options for upgrading the home's energy efficiency. The homeowner may then use the report to decide which upgrades will be cost-effective, and determine how long it will take to recover the improvement costs through energy savings. A home energy rating of a new home (called a "projected rating") allows potential homebuyers to compare the relative energy efficiency of different homes they are considering.
The U.S. Department of Energy created a similar home efficiency scale, based on RESNET's HERS Index. The Department of Energy's rating system uses a 1–100 scale; a rating of 50 indicates average energy performance, while a rating of 75 or better indicates top performance. The Department of Energy's EnergySmart Home E-Scale also uses an interactive tool to chart potential energy savings; to estimate energy usage in your home based on the E-Scale score, try the E-Scale Interactive Tool.