The RESNET Home Efficiency Rating System

The Residential Energy Services Network’s (RESNET) Home Efficiency Rating System (HERS) Index Score was created to provide homeowners and buyers a standard by which they could measure the energy efficiency of homes. Like the auto industry’s fuel efficiency MPG sticker, HERS scores are used by homebuilders to market their properties. To calculate a home’s HERS score, a certified RESNET Home Energy Rater does a home energy rating and compares the data against a “reference house” — a designated model home of the same size, shape and type. As such, HERS is a relative index rating on a scale from 0 to 150, and the lower the number, the better the energy efficiency.

A typical new home built in 2006 has a HERS rating of about 80. By comparison, houses built 40 years ago are typically rated at about 130, which means they are about 50% less energy efficient. The IECC 2015 Energy Code requires all new homes finished on or after June 1, 2016 to have a HERS rating of 52 or less, and the expectation within the building industry is that the regulatory bodies will inevitably move towards adopting a HERS rating of 0 for newly built houses.

“You can build homes that will meet these new energy efficiency levels using conventional materials, but it takes a lot more materials and labor,” says Composite Panel Building Systems’ principal Vince Nastri.