What is a HERS Rating, and Why Does it Matter?

HERS Rating IndexAt Building Performance, we get a lot of questions about the Home Energy Rating System (HERS) Index from both builders and our customers. While it may seem confusing, the HERS Index is relatively straightforward. It's essentially a measurement of your home's energy efficiency, measuring an approximation of costs associated with heating and cooling, as well as lighting and appliance usage for the home. Scores range from 0 to 150+, with higher scores indicating poor home efficiency and lower scores reserved for homes that are performing at optimum efficiency.

Since the HERS rating applies specifically to how well your home performs, it does matter. The more you can learn about the system and factors that can influence ratings, the better.

Factors Affecting HERS Ratings

Your home’s energy efficiency and performance can be affected by a number of different factors, some of which Louisville, KY homeowners don’t even realize. These include (but are not limited to) the following:

  • All Exterior Walls

  • Floors Over Unconditioned Spaces

  • Ceilings and Roofs

  • Attics, Foundations and Crawlspaces

  • Windows and Doors

  • Vents and Ductwork

  • HVAC Systems

  • Water Heating Systems

  • Lights & Appliances

  • Thermostats

  • Air Leakage

  • ...and more

Beneficial for Both Builders and Homeowners

It’s easy to assume that the HERS Index is something that is reserved only for contractors and builders, but homeowners stand to gain quite a bit from learning more about it. A HERS rating can help identify the major issues related to energy use and comfort problems in a home,  and this information can then be used to develop a game plan to make the most cost-effective improvements possible.  Call this the “blueprint” for any home performance improvements you want to do.


For builders, the HERS Index helps in developing a plan for improving a home’s performance right from the start.  Once the architectural design is complete, but before they even begin building, they’ll know what type of insulation, windows and doors to use to make the house more comfortable & efficient, and they’ll also know what size the heating & cooling system needs to be for optimal efficiency.  Then, once the house is under construction, the HERS Rater will do at least two onsite inspections to verify the materials spec’d have been installed properly, and any deficiencies found can then be corrected before drywall covers them up, avoiding potentially costly repairs down the road.  Finally, once the house is substantially complete, the HERS Rater returns to verify the intended performance results by testing the house for air-leakage, duct-leakage, and air-flow through ventilation systems.


Here's a video detailing the final inspection process:


How to Improve a HERS Rating

No homeowner wants to find out that their home’s HERS Rating is too high (bad), but it’s important to realize that even if this occurs, most problems can be fixed and the rating improved. It all starts with identifying exactly what’s causing the poor performance to occur in the first place, which requires an on-site visual inspection along with the aforementioned performance testing.


A Building Performance team member will take a close look at how well your home is performing and will isolate any issues that are at play. For commercial clients, we provide energy audits post-construction to ensure your structure is performing up to par.


We’ll answer any questions you may have during the process, and we encourage you to come on a walk-along to learn about exactly how your home or building can benefit from certain home performance upgrades.

Don’t let the HERS Index mystify you—contact us today to schedule an inspection!