What is HERS Testing in California?

Learn about the HERS test, a home energy rating system in California. Find HERS testing near you and trust Sandium for expert guidance on energy efficiency in your home.

Updated on Oct 22, 2023
5 min read
What is HERS Testing in California?

HERS testing or Home Energy Rating System testing involves examining the energy efficiency of a house. It notes those areas where energy efficiency can be improved. HERS testing is a requirement in California and is particularly important when you are purchasing a new house in California. This post will explain what HERS testing is and when do you need it.

Understanding HERS Testing and Rating

HERS program is born out of California and is implemented throughout the United States. It addresses improper equipment installations and construction defects. HERS testing uses a scale of 0 – 250 for determining the energy efficiency rating of a house. It indicate whether all major appliances and systems in the house meet state standards for energy efficiency.

HERS testing is completed by a HERS rater and takes about 2 – 4 hours. RESNET (Residential Energy Services Network) developed the HERS Index on which the HERS rating is based. Lower numbers on the HERS Index indicate better energy efficiency. Homeowners and potential home buyers gain an insight on how the house ranks. HERS Index is validated by the Environmental Protection Agency (EPA), the US Department of Energy (DOE), and the Department of Housing and Urban Development (HUD) as an official verification of the home energy performance.

Calculation of HERS Rating

A HERS rater will test your home before calculating the HERS rating. Your house will be assessed on its energy efficiency and the data compared with a reference home. This reference will be on a designed model home of the same shape and size to ensure the score is relative to the house you live in. Visual inspection and diagnostic testing of energy efficiency features and physical characteristics is used for basing the home energy rating.

These are a few features evaluated:

  • HVAC system
  • Ceilings and roof
  • All exterior walls
  • Vents and ductwork
  • Air leakage in the home
  • Floors over garage and other unconditioned spaces

What to Expect?

There are three tests commonly performed by a HERS rater. These are:

  1. Duct leakage testing: Duct tests measure the amount of air leaks in unconditioned areas of the duct system
  2. Refrigerant charge verification: This measures the performance of the air conditioning system and verifies the refrigerant levels are as per manufacturer specifications
  3. Airflow verification: This test is used in conjunction with the refrigerant charge verification. It measures the air velocity flowing through the ducting system during air conditioning cycle.

When to Get HERS Testing

HERS testing is necessary when building, buying or selling a house. HERS testing has a major impact on the resale value of a house. It can let a new buyer know about the kind of energy expenditure to expect. The testing helps builders ensure their appliances and systems meet Californian energy efficiency standards.

In California, all contractors and homeowners are required to comply with the guidelines laid down in the “California Code of Regulations Title 24, Part 6, Energy Efficiency Standards for Residential and Nonresidential Buildings”. Homeowners are also required to schedule HERS testing when they install a new mechanical system which requires testing and verification.

This is as per Title 24, Part 6 of the HERS Program developed by the California Energy Commission for differentiating between energy efficiency levels. 

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