HERS (Home Energy Rating System) Index
Technology Snapshot & Benefits:
The HERS Index is a scoring system developed by the Residential Energy
Services Network (RESNET). The index was developed as a part of the overall home
energy rating system in order to develop a standard measurement of a home's
energy efficiency and expected energy costs. The HERS Index is based on the
measured energy efficiency performance of the standard (average) new home. This
standard is demarcated as a 100 on the HERS Index, for every point above or
below 100, the home is that many % less or more efficient than the same home
built to code. For example a home with a HERS Index of 80 is 20% more efficient
than its code-built counterpart. In other words, lower numbers are better (click
to see scale). A HERS Index of 0 means it's a
Net Zero Home (it produces as much energy as it uses each year).
This index proves valuable when comparing homes of varying energy efficiency
levels to a quantifiable standard measurement which allows for all homes to be
compared on the same scale.
In order to generate a HERS Index score a
rater will conduct onsite inspections, typically including an insulation
blower door test and a duct test amongst other analysis such as the use of
specially designed software to analyze the expected energy use of the home. In
addition to considering heating, cooling, and hot water, the HERS Index takes
into account energy use for lighting and major appliances as well as renewable
energy produced on site. Results from these tests, along with the data from the
software analysis, are used to compile a final HERS Index score for the home.
Estimated Cost Savings:
The HERS Index is used as a current or predicted indication of a home's
energy efficiency and expected energy costs. A home energy rating can qualify
the home for programs such as Energy Star (requiring a score of 85 or lower) or
help the home owner or buyer qualify for an energy efficient mortgage or an
energy improvement mortgage. By having your home measured on the HERS Index an
accurate and comparable snapshot of a home's performance can help the owner or
buyer understand where their home's energy efficiency performance stands and
what needs to be done to improve that performance. A good HERS Index score not
only helps to improve the comfort and efficiency of your home, but it can also
improve the resale value and allow you to communicate the efficiency level of
your home to potential buyers.
Use caution when hiring a home energy rater. Hire a certified rater to conduct
the rating and determine the HERS Index. A certified rater will have the proper
training, knowhow, software, and tools to adequately evaluate the home and
produce a quantifiable and reliable measurement of energy performance.
In some areas it may be more difficult to have a home energy rating conducted
due to the volume of certified energy raters in your region. It is important to
make sure that when a home energy rating is done that it is conducted in a
manner which addresses regionally specific energy demands and supplies, as well
as regional climate and site specific weatherization issues.
RESNET's website and your local utility provider are both good places to
start when looking for professionals to conduct home energy ratings and
determine your home's HERS Index score. Other resources to find certified home
energy raters include the lists of approved affiliates found at both
Energy Star, and
EcoBroker. Hire a professional who knows your climate, knows what they're
doing, and ideally, who has had a lot of hands on experience and has worked on
More Information On This Topic:
Energy Star - The HERS Index
Energy Star - What is a HERS rating?
Energy Vanguard - Home Energy Rating Lingo
RESNET - What Is A Home Energy Rating?