Home Energy Rating System (HERS) is the most in-depth energy performance assessment of a home you’ll find.
A home energy rating is an analysis of a home’s energy efficiency as per the HERS Index. The HERS Index is the nationally recognized scoring system for measuring a home’s energy performance. Based on the results, an energy-rated home will receive a HERS Index Score. The HERS Index Score can be described as a sort of miles-per-gallon (MPG) sticker for houses, giving prospective buyers and homeowners an insight as to how the home ranks in terms of energy efficiency. In addition to a HERS Index Score, a home energy rating also provides the homeowner with a detailed report regarding energy problems in the house.
How Does a Home Energy Rating Work?
A comprehensive HERS home energy rating, conducted by a certified RESNET Home Energy Rater, is the most in-depth energy performance assessment of a home that you’ll find. It consists of diagnostic testing using specialized equipment, such as a blower door test, duct leakage tester, combustion analyzer and infrared cameras to determine:
• The amount and location of air leaks in the building envelope
• The amount of leakage from HVAC distribution ducts
• The effectiveness of insulation inside walls and ceilings
• Any existing or potential combustion safety issues
Other variables that are taken into account include:
• Floors over unconditioned spaces (like garages or cellars)
• Attics, foundations and crawlspaces
• Windows and doors, vents and ductwork
• Water heating system and thermostats
The comprehensive HERS rating provides a computerized simulation analysis utilizing RESNET Accredited Rating Software to calculate a rating score on the HERS Index. The report will also contain a cost/benefit analysis for the recommended improvements and expected return on investment.
How Does the HERS Index Work?
To calculate a home’s HERS Index Score, a certified RESNET Home Energy Rater will do a home energy rating and compare the data against a ‘reference home’ – a design modeled home of the same size and shape as the actual home, so the HERS Index Score is always relative to the size, shape and type of house you live in. The lower the number, the more energy efficient the home.
The U.S. Department of Energy has determined that a typical resale home scores 130 on the HERS Index while a standard new home is rated at 100.
A typical resale home represents 130 on the HERS Index while reference home (a standard new home built in 2006) is rated at 100.
• A home with a HERS Index Score of 70 is 30% more energy efficient than a standard new home.
• A home with a HERS Index Score of 130 is 30% less energy efficient than a standard new home.
Developed by the Residential Energy Services Network and introduced in 2006, the HERS Index is the industry standard by which a home’s energy efficiency is measured. Government agencies such as the Department of Energy (DOE), Department of Housing and Urban Development (HUD) and the Environmental Protection Agency (EPA) recognize the HERS Index as an official verification of energy performance.