HERs Ratings

climate zones of california

A Home Energy Rating System was established to be a third party verification agency to inspect and test home energy improvements. Today we are constantly seeing new regulations come into effect. A HERS Rater is someone who would come out to test and verify the findings of the contractor or builder. The most typical example would be a duct test.

The State of California is broken up into 16 different climate zones. Each of these climates zones represents a micro-climate that has dramatically different weather and energy demands. In our immediate area, we see two climate zones. Climate Zone 13 represents most of the San Joaquin valley and is considered a Desert climate zone. The second climate zone is Climate Zone 16, which exists once you start to climb the Sierras to the east, and would include areas like Bass Lake, Shaver Lake, Yosemite, and the higher elevations. HERs tests that are required in Fresno are not necessarily required at Shaver Lake.

In most climate zones, a duct test is required with a maximum allowable leakage target. This means that any time you change any piece of your HVAC system, the contractor is required to seal the duct work if it doesn't already meet this target. To complicate matters, there are two different targets, 15% for existing systems, and 6% for completely new systems, inlcudling new homes. This test is then verified by a HERS Rater. The job of the rater is to perform the test to ensure that the contractor did the job correctly, per the regional energy standards, where as the inspector's job is to check for compliance to the building codes. The inspector will ask for the HERs forms at the time of inspection.

Other HVAC specific tests involving a HERS rater and air conditioning contractor are fan watt and airflow, Energy Efficiecny Ratio (EER) verification, refrigerant charge, and vertified cooling capacity. Most of these tests are performed on new construction jobs. Although some of these verifications are also required on retrofits and remodels.

There are additional HERs tests that extend beyond the HVAC system, too. A Blower Door test involves sealing all hoods vents and windows/doors. You then would de-pressurize the whole house giving you an air leakage number. This air leakage number measures the infiltration rate, which is the rate at which outside air finds it way into your house. Typical leakage points are around sheet rock penetrations (can lights, electrical plugs, registers). This test verifies that the house is relatively tight, as a tight house is one that is easier to control, whether it be temperature, humidity, or even general health. This test is typically done on new construction, although it is needed when you perform an energy audit on an existing home.

Insulation Verification is one of the most important tests for new construction. To put it simply, can you see through your walls? No. So it is important this test be performed. Insulation in most attics is pretty easy to access and increase as needed. However, it is almost impossible to get into walls after sheet rock, without cutting holes. Ideally one never has to cut into a wall for any reason after they house is built!

The State of California believes HERS testing is important to keep contractors honest about the work that was done on a house whether it is new construction or a remodel.

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