What is the Home Energy Rating System (HERS) ?

HERS (Home Energy Rating System) is a rating system developed by RESNET in order to measure how efficient a home performs.

The home energy rating process basically comprises four parts:

  • Assessment of building components
  • Diagnostic/performance testing
  • Energy modeling
  • Reports

Your home gets a HERS Index (a.k.a. HERS Score) by a certified home energy rater.  You would probably get a HERS Score after your certified home energy rater performs a home energy audit.

In April 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 market for home energy rating systems and energy efficient mortgages.

RESNET’s standards are officially recognized by the federal government for verification of building energy performance for such programs as federal tax incentives, the Environmental Protection Agency’s ENERGY STAR program and the U.S. Department of Energy’s Building America Program.

A home energy rating involves an analysis of a home’s construction plans and onsite inspections. Based on the home’s plans, the Home Energy Rater uses an energy efficiency software package to perform an energy analysis of the home’s design. This analysis yields a projected, pre-construction HERS Index.

Upon completion of the plan review, the rater will work with the builder to identify the energy efficiency improvements needed to ensure the house will meet ENERGY STAR performance guidelines. The rater then conducts onsite inspections, typically including a blower door test (to test the leakiness of the house) and a duct test (to test the leakiness of the ducts). Results of these tests, along with inputs derived from the plan review, are used to generate the HERS Index for the home.

Unlike a Building Performance Audit or a weatherization assessment, a home energy rating is a recognized tool in the mortgage industry. Home energy ratings can be used in a variety of ways in the housing industry. Since a rating quantifies the energy performance of a home, the HERS Index provides an easily understandable means to compare the relative energy efficiency of different homes.

The HERS Index

HERS Index Energy ConsumptionThe HERS Index is a scoring system established by the Residential Energy Services Network (RESNET) in which a home built to the specifications of the HERS Reference Home (based on the 2006 International Energy Conservation Code) scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The lower a home’s HERS Index, the more energy efficient it is in comparison to the HERS Reference Home.

Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home. Thus a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home and a home with a HERS Index of 80 is 20% more energy efficient.

A HERS Index of zero means it’s a Net Zero Home (i.e., it produces as much energy as it uses each year).

Frequently Asked Questions

About Ratings

Accredited rater training providers provide the training that rater candidates are required to successfully complete in order to become certified by an accredited rating provider.

Q: What is a home energy rating?
A: The home energy rating is a standard measurement of the home’s energy efficiency. An energy rating allows a home buyer to easily compare the energy costs for the homes being considered.

Q: What is involved in a home energy rating?
A: Home energy ratings involve an on-site inspection by a residential energy efficiency professional – a home energy rater. Home energy raters are trained and certified by a RESNET accredited home energy rating system.

The home energy rater inspects the home and measures its energy characteristics, such as insulation levels, window efficiency, wall-to-window ratios, the heating and cooling system efficiency, and the solar orientation of the home.

Performance testing, such as a blower door test measuring door and duct leakage may be used. The home receives a point score between 1 and 100, depending on its relative efficiency. An estimate of the home’s energy costs is also provided. A homeowner who wants to upgrade the energy efficiency can use the energy rating to evaluate and pinpoint specific, cost-effective improvements.

Q: Can I trust the results of a home energy rating?
A: Home energy ratings must meet the stringent standards developed by RESNET. Raters must abide by a code of ethics, rating standards of practice, and most disclose all financial interests to the client. The mortgage industry recognizes the rating to qualify for an energy efficient mortgage.

Q: What can I do with an energy rating?
A: The energy rating provides the following benefits:

  • When buying a home a rating allows you to compare homes according to their energy efficiency
  • A rating allows you to know the energy performance of your home and identifies cost effective improvements that you can make to increase your comfort and home’s performance.
  • A rating is required to qualify the home for an energy efficient mortgage
  • A rating is required for a home to be labeled as ENERGY STAR

Your HERS Score comes in handy in several places:

  1. Stand-alone score: By itself, it gives you a good idea of how your home compares to a baseline home.  I’m a firm believer that when we have quantitative values to use for comparison we are able to better define how we need to improve.  For instance, you can get a certified Home Energy Rater to analyze your home on date 1, then you can make the suggested improvement, and at date 2 you can get your home rated again to see how much your score has improved.
  2. LEED for Homes: If you want to get a LEED score for your home, like Lorraine and Judd Horalby who we covered in our post on LEED for Homes, then chances are it will utilize the HERS index to help determine what level of LEED status your home will achieve.
  3. Energy Star for Homes: Energy Star for Homes is different than Home Star (a.k.a. Cash for Caulkers bill) but is yet another energy efficient stamp of approval (just like LEED for Homes is).  LEED for Homes is monitored by the U.S. Green Building Council (which actually is not a government program, it is a non-profit) while Energy Star for Homes is a joint project by the U.S. DOE and EPA.  The EnergyStar website has a nice summary of the relationship between the HERS Index and Energy Star for Homes: “A home energy rating involves an analysis of a home’s construction plans and onsite inspections. Based on the home’s plans, the Home Energy Rater uses an energy efficiency software package to perform an energy analysis of the home’s design. This analysis yields a projected, pre-construction HERS Index. Upon completion of the plan review, the rater will work with the builder to identify the energy efficiency improvements needed to ensure the house will meet ENERGY STAR performance guidelines.”

As you can see, HERS and the HERS Index (Score) come in handy in several places (yes, I know it gets confusing sometimes).  By giving home energy raters a set of standards to measure how efficient a home performs, HERS helps homeowners and homebuilders understand how efficient their home is and how they can improve.

Source: www.resnet.us

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