Get to Know the HERS Index

Scoring new homes for energy efficiency gives builders a timely selling tool.

A bright yellow EnergyGuide sticker would look rather silly on the front door of a new energy-efficient home, but many builders are touting a rating that's similar to what's been prominently displayed on refrigerators, washers, dryers, and other home appliances for years. It's a home's HERS Index, a method of scoring the energy efficiency of a new (or existing) home.

The HERS (Home Energy Rating System) Index was established in 2006 by the Residential Energy Services Network (RESNET), a California-based national association of home energy raters and energy-efficiency mortgage lenders. RESNET was formed in 1995 by the National Association of State Energy Officials and Energy Rated Homes of America.

The HERS Index works like this: A home built to the specifications of the HERS Reference Home (based on the 2004 International Energy Conservation Code) gets a HERS Index score of 100 while a net zero energy home gets a HERS Index score of 0. The lower a home's score, the more energy efficient it is in comparison with the HERS Reference Home.

Each one-point decrease in the HERS score corresponds to a 1 percent reduction in energy consumption compared with the reference home. To calculate a home's score a rater uses a software program — most often REM/Rate, one of four software programs approved by RESNET.

The HERS Index is now a nationally recognized benchmark, but in the past there have been some complaints that a large house had a better chance of getting a lower (better) HERS score than a smaller home. RESNET's board of directors recently voted to change some elements of the algorithms used to calculate the HERS score, which should help decrease any penalty for smaller homes.

What few would argue with is the usefulness of rating a home's energy efficiency, something that builders looking for a niche would be wise to pursue. Americans have come to rely on EnergyGuide ratings for their new appliances. It won't take long for homebuyers to expect see a similar rating — the HERS Index score — attached to a prospective new home.

So what does all this have to do with propane? Well, as demonstrated by the Propane Energy Pod building model, propane systems can help a home get a lower HERS score than it would get with standard equipment built with systems running on electricity or heating oil. For example, a 2,400-square-foot home in Connecticut that scores an 83 with standard equipment could be built to score a 67 by following the Propane Energy Pod model. The same home would save $251 each year on energy and have a carbon emissions footprint that is 21 percent smaller. See for yourself by using the Propane Energy Pod interactive tool.


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