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HERS Ratings and Verifications


HERS stands for Home Energy Rating System and was established in the early 1990’s as a method to calculate and put a number to the energy efficiency of a residence. The first raters were certified in the early to mid 1990’s.  The ratings produced by these first raters were to be utilized by mortgage lenders to allow a homebuyer to extend their debt to income ratio if buying a home already up to energy standards, or to allow more money to be included in the mortgage so energy efficiency upgrades could be installed in a newly purchased home. The HERS rating gave a number to a home energy conservation performance much like a “miles per gallon” number for a car.  These types of raters are also known as “whole house raters” and require special certification to perform these ratings.


A few years later the HERS scope was widened to include duties as a special inspector to test and verify energy measures installed in new and existing homes that had historically been installed incorrectly. Now when the energy codes are updated every three years, each update specifies a more active role for the HERS rater in assisting the local building department in verifying and testing various installations. Whether an installation is done in the correct manner, or whether the correct equipment was installed, takes special training and equipment to determine. In addition the length of time it takes to perform some of the testing and verification procedures would put undue stress on a local building official. So some of those duties are now performed by the HERS rater.

So the HERS rater not only performs whole house energy ratings but also is certified to run special tests to ascertain whether certain pieces of HVAC equipment are working correctly. To successfully do the required group of tests on a newly installed HVAC system includes a duct pressure test, measuring the air flow over the cooling coil, determining the fan watt draw, and using sub-cool or super-heat calculations  to determine whether the correct amount of refrigerant has been installed in the A/C compressor. These tests can take between one and two hours so the local building official just doesn’t have the time to do these tests.

The results of the tests done in the field must then be entered into a State Of California approved registry. This process takes more time, usually between 20-30 minutes or more. With every code change cycle we see more and more testing and verifications given over to the HERS rater. HERS raters now check and test not only HVAC equipment but check the air flow of the fan required to meet the specifications for Indoor Air Quality. In addition a HERS verification is required for QII (Quality Insulation Installation), water heating devices, lighting fixtures and solar systems. Each inspection or verification has it’s own set of forms that must be completed and registered in the Registry. As of this writing that group of forms totals almost 100 different inspections and verifications.  For more information on this topic, check out our Title 24 page.

It appears HERS raters and the things they do will be with us for some time to come.