HERS Index – Understanding the HERS Score

The RESNET HERS Index is the industry standard by which a home’s energy efficiency is measured. The HERS or Home Energy Rating System was developed by RESNET and is the nationally recognized system for inspecting and calculating a home’s energy performance. Certified RESNET Home Energy Raters conduct inspections to verify a home’s energy performance and determine what improvements can be made to increase it.

HERS Index Score of 150

This house is a WHOPPING 50% LESS ENERGY EFFICIENT than a standard new home! It could be a significant financial drain on the bank account and to the environment in general. A house like this has high energy bills and will be hot in the summer and cold in the winter. This homeowner should immediately talk to a RESNET certified Home Energy Rater who can advise them on what they can do to:

  • Improve their home’s comfort level.
  • Reduce their energy costs.
  • Make their home more environmentally friendly.

HERS Index Score of 140

This score puts this house near the very top of the HERS Index; a position a homeowner definitely doesn’t want to be in! What this translates into, in terms of energy efficiency, is that this home is performing 40% worse than a home adhering to the basic building code requirements. This is probably one of the major reasons for its high energy costs, less than ideal comfort level and, though one might not be directly aware of it, its negative impact on the environment.

HERS Index Score of 130

This is the typical resale home score. That means if you’re in the market for a home, this house will be at least 30% less energy efficient than it should be. Therefore, the smart way to buy a home is to determine its HERS Index score before you decide to buy. If you decide to purchase such a house, you should definitely consider taking advantage of an Energy Improvement Mortgage.

HERS Index Score of 120

This home is 20% less energy efficient than a standard new home. Watch out for the noticeably draftier rooms, the fact that utility bills are higher than a newly constructed home and that the house is either too hot in summer or too cold in winter. While this home isn’t quite the inefficient energy monster, it would be a good idea to get in touch with a certified RESNET Rater to discover what options are available on improving its energy performance.

HERS Index Score of 110

You’re pretty close to bringing your home in line with the current industry standard for energy conservation. However, there’s still a lot of room for improvement, and that can translate directly into an improved quality of life and savings on your home energy bills. This is a good time to look into getting an Energy Improvement Mortgage that can help you to make the necessary improvements to your home.

HERS Index Score of 100

Your home is at the same level as a standard new home, which meets the current industry standard for home energy efficiency. But that doesn’t mean your home is working at its optimal efficiency! There are still many energy saving measures that you could implement to make your home much more energy efficient, resulting in a safer home environment, lower utility bills and a better effect on the environment.

HERS Index Score of 90

This home is 40% more energy efficient than an average resale home and 10% more energy efficient than a standard new home, which is awarded a score of 100 and used as the base against which all other homes are measured. The lower a home ranks on the HERS Index, the better it is both financially and environmentally. Also, a low HERS Index score could help increase a home’s resale value as well! RESNET certified Raters can show you how to improve your house’s ranking on the HERS Index, increase your quality of life and add value to your home.

HERS Index Score of 80

You might think this house is doing okay when it comes to home energy efficiency – but the fact is it could do a lot better. Although this house might be performing 20% more efficiently than a standard new home, homes can be built much more energy efficiently. Money invested into a more energy efficient home will help increase its value while improving its comfort level.

HERS Index Score of 70

This is an admirable score. Although this home is 30% more energy efficient than homes built according to current building code requirements, it is still possible to lower the HERS Index score. A RESNET certified Rater can advise homeowners on what home energy performance features they can add that will add value to their home and improve its comfort level.

HERS Index Score of 60

This house has made good progress towards optimizing its energy performance! Not only is this good news from a financial point of view, it’s also good news for the environment. Did you know that 16% of greenhouse gases generated in the U.S. come from homes?

HERS Index Score of 50

This home is 50% more energy efficient than a standard new home and 80% more efficient that the average resale home, which already puts it in a better bracket than a standard new home. However, there are still many improvements that can be made. A RESNET certified Rater is the ideal person to talk to about what more can be done.

HERS Index Score of 40

This is a very good score indeed! The builder has done a lot of the right things to make this home more energy efficient, like using energy efficient lighting systems and installing efficient heating and cooling equipment. A RESNET certified Rater can make recommendations on further improvements that could result in even greater savings.

HERS Index Score of 30

A great score! This home is 70% more energy efficient than a standard new home and 100% more efficient than the typical resale home! It has been designed and built with energy efficiency in mind, resulting in a home that is environmentally friendly, enjoys a high comfort level and benefits from low energy costs.

HERS Index Score of 20

This is a tremendous score! This house is well on its way to becoming a Zero Energy Home, which is environmentally friendly and produces as much energy as it consumes. Homeowners can apply for Energy Efficient Mortgages to help them finance the energy improvements they need to transform their homes into high energy performance ones.

HERS Index Score of 10

This is a truly outstanding score! Tremendous effort has gone into making this home very energy efficient. These homeowners will enjoy watching their utility bills decrease while the comfort level of their home increases. The next step would be to eliminate energy costs altogether by having the house produce its own energy. A RESNET certified Rater can show you how you to convert your home into a Zero Energy Home that actually produces as much energy as it consumes.

HERS Index Score of 0 (Net Zero)

This home is a Net Zero Energy Home. This means that this home produces as much energy through renewable resources, such as solar panels, as it consumes. Only a Net Zero Energy Home can score 0 on the RESNET HERS Index. Among the advantages of a Zero Energy Home are:

  • Improved health and comfort: a Net Zero Energy Home reduces temperature fluctuations.
  • Cost effective: a Net Zero Energy Home that produces energy not only shields its owner from fluctuations in energy prices but can eliminate energy bills altogether.
  • Environmental sustainability: a Net Zero Energy Home protects the environment by reducing greenhouse gases, cutting carbon emissions and saving energy.


This content was originally published by the Residential Energy Services Network (RESNET) here. This content has been republished with the permission of RESNET. RESNET is the independent, national nonprofit organization that homeowners trust to improve home energy efficiency and realize substantial savings on their utility bills. RESNET’s industry-leading standards are recognized by the U.S. Department of Energy and the U.S. Environmental Protection Agency, among others.