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Home Energy Science offers services specifically tailored to the needs of
- Homeowners
- Homebuyers
- Realtors
- Builders
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What is the Home Energy Rating System?
A home energy rating involves an analysis of a home’s construction plans and onsite inspections. Based on the home’s plans, the Home Energy Rater uses an energy efficiency software package to perform an energy analysis of the home’s design. This analysis yields a projected, pre-construction HERS Index. Upon completion of the plan review, the rater will work with the builder to identify the energy efficiency improvements needed to ensure the house will meet ENERGY STAR performance guidelines. The rater then conducts onsite inspections, typically including a blower door test (to test the leakiness of the house) and a duct test (to test the leakiness of the ducts). Results of these tests, along with inputs derived from the plan review, are used to generate the HERS Index score for the home.
The HERS Index
The HERS Index is a scoring system established by the Residential Energy Services Network (RESNET) in which a home built to the specifications of the HERS Reference Home (based on the 2006 International Energy Conservation Code) scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The lower a home’s HERS Index, the more energy efficient it is in comparison to the HERS Reference Home.
Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home. Thus a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home and a home with a HERS Index of 80 is 20% more energy efficient.
- A relative energy use index called the HERS® Index – a HERS Index of 100 represents the energy use of the “American Standard Building” and an Index of 0 (zero) indicates that the Proposed Building uses no net purchased energy (a Zero Energy Building)
- A set of rater recommendations for cost-effective improvements that can be achieved by the Rated Building
How is the HERS Index calculated?
- Proposed (or As-built) Building and the Standard Building are modeled using accredited building simulation software tools and the results are ratioed (Proposed divided by Standard times 100)
- Software accreditation is achieved by passing a battery of software verification tests developed by U.S. National Laboratories and RESNET
- Software is required to automatically generate the Standard Building using only the input form the Proposed Building (i.e. software users have no control over the configuration and modeling of the Standard Building)
- Configuration and modeling parameters for the Standard Building are carefully and completely specified as a modeling “rule set.”