What is the RESNET HERS Index?

What is the RESNET HERS Index?

RESNET uses the Home Energy Rating System (HERS) to rate a home's energy efficiency.

The HERS Index illustrates a range of numbers, or scores, that can be used to compare the energy use of two homes.

RESNET HERS Raters are trained to perform diagnostic tests and use energy modeling software to output a HERS Score for a home.

HERS Index
How It Works

What the HERS Score Means

home energy rating

The HERS Score is a number that represents the relative energy use of a rated home as compared with the energy use of a home built to today's minimum building code. The HERS system allows for an apples-to-apples energy efficiency comparison of different houses.

  • A HERS Index of 100 represents the energy use of the standard home
  • A HERS Index of 0 represents a home that uses no net purchased energy

A HERS Rater provides recommendations for cost-effective improvements that can reduce energy use in a home (and therefore lower the HERS score).


How the HERS Score Gets Calculated

Computer software, such as REM/Rate, is used to analyze the results of an in-depth assessment of an existing home or the components of a new home design. The assessment includes analysis and inspection of:

  • windows, doors, insulation, and ducts to find and measure leaks
  • all heating and cooling equipment to ensure occupant health and safety

Specialized diagnostic equipment, such as a blower door and duct blaster, help to provide detailed measurements of the energy efficiency issues. In addition to yielding an energy rating, the report will provide a cost benefit/analysis, with expected return on investment for suggested repairs and upgrades. This makes it easier for the homeowner to prioritize recommended treatments.

energy code compliance

How is the HERS Score Used?

RESNET has grown in popularity as a result of its far-reaching impacts.

Here are several examples of groups that use the HERS score:


use home energy ratings in establishing minimum building code compliance


use scores to estimate the cost of maintaining a particular home and evaluate the cost-effectiveness of options that can improve energy efficiency.


modify home designs based on rating guidelines to meet buyer demand for maximum comfort at a minimal cost.

Mortgage Companies

recognize ratings as a tool and require them to qualify loan applicants for certain federally sponsored mortgage products.


Sign Up for RESNET HERS Rater Training

Now that you have a basic understanding of the HERS Index, take a deeper dive with the full RESNET HERS Rater training program!


Still have questions about RESNET? Check out our RESNET FAQs page.