HERS, or Home Energy Rating System, testing might sound like a confusing thing, but it’s really a simple enough subject once you dig into it a little.
This guide will help you get a better understanding of HERS testing for your home.
What is HERS Testing?
Home Energy Rating System (HERS) testing is the measurement of the energy efficiency of your home. It’s basically a report of how efficient your home is and the aspects of your home that can be changed in order to improve its efficiency.
“Efficiency” in this context is a bit unclear and needs more explanation. As the test’s name explains we are concerned with energy efficiency, but this too can mean many different things. The test measures and rates your energy usage in terms of electricity, heating, air conditioning, HVAC, and other usages of “energy.”
A HERS test is conducted by a licensed professional who will look at many aspects of your home in order to deliver a HERS index score. This score is a measurement of how efficient your home is and is a good proxy for your how much your energy costs could be lowered if your house, say, had fewer air leaks and let cold air in in the winter and thus had your furnace running more than it should.
HERS ratings are done by certified inspectors who work through RESNET, the Residential Energy Services Network, in the Unites States. Other countries have equivalent services with their own certifying organizations.
What Does HERS Measure?
A HERS inspector will look at many parts of your home including:
- Roof (primarily from attic)
- Ceilings
- Floors
- Foundation
- HVAC
- Water heating
- Thermostats
- Windows and Doors
- Vents and Ducts
- Exterior and Interior Walls
These parts of your home are inspected and the combined results are put on a rating scale. Things like heat loss, air leakage, insulation R-value, and more are taken into account.
How Does A HERS Rating Work
The baseline for this scale is 100, which is designed to represent a typical American home. If a home is built in 2021 and follows building codes it should score at least a 100.
The HERS scale is relatively, so a home with a rating of 150 will use 50% more energy than a home with a rating of 100. This means that older homes will skew higher in the scale and newer homes will average 100, but might possibly be lower.
If a home has a HERS rating of 40 it will use about 40% the power of a standard US home of 2021.
A Zero Energy Ready Home will range from 1-50 on the HERS scale, as will a LEED for Home qualified house. A “passive home” is generally considered to be 35 or under, where a “positive home” will have a negative value!
As you might have guessed a home with a 0 rating will either use no energy (unlikely) or it will use no net energy, which means its energy usage will be countered exactly by energy created through wind, solar, or a similar capture system.
HERS is not a US Department of Energy (DoE) rating, and it’s not part of the DoE’s Better Buildings program, but the organization does recognize HERS. The DoE does use the Zero Energy Ready Homes rating, which is likens to HERS, noting that a Zero Energy Ready Home will be similar to a HERS rating of 40-50.
There is also such a thing as EnergyStar for buildings, which differs from HERS and LEED, but is in the range of a home below 80 on HERS.
Should You Get A HERS Test?
HERS testing is useful under a few different circumstances. The best application is if you build a new home and expect to live in it for an extended period of time, you’ll save costs in the long run by having it be maximally efficient. A HERS test early in your home’s life makes sense.
HERS testing is also great if you have invested in your home and want to see that investment reflected in a quantitative rating in order to boost the resale value of your home. When you are selling a home it can be hard for the buyer to assess the worthiness of the investments the previous owner had made, especially technical ones like insulation or replaced duct work. A low HERS score will be excellent proof of home being well-constructed and efficient to live in.
HERS testing is also good for assessing the impact of work you have had done. If you pay $10,000 for spray foam insulation you’ll want to know the job was done well and will have an impact. HERS testing will accomodate this.
Where Do I Find A HERS Tester?
The easiest place for this is through the official RESNET website.