A home energy rating can be used to gauge the current energy efficiency of a home or estimate the efficiency of a home that is being constructed or improved. A home energy rating of a home prior to construction or improvement is called a “projected rating.” A home energy rating that is used to determine a home’s current efficiency is referred to as a “confirmed rating.”
Energy assessments take into account different climatic conditions in different parts of the country and are benchmarked according to average household energy consumption particular to a given climatic region.
HERS Index and related scales
RESNET HERS Index
Ratings provide 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 building uses no net purchased energy (a Zero Energy Building). The lower the value, the better.
For capitalizing a building’s energy performance in the mortgage loan, certification of “White Tags” for private financial investors, and by the US government for verification of building energy performance for such programs as federal tax incentives, the United States Environmental Protection Agency’s Energy Star program and the U.S. Department of Energy’s Building America Program.
The HERS Index was introduced in 2006 and replaced the earlier “HERS Score“, which ran in the opposite direction: The higher the value, the better. In 2009, the U.S. Department of Energy presented a new scale, the “EnergySmart Home Scale (E-Scale)”, “based on” the HERS Index, apparently simply by subtracting the HERS Index from 100. In this new scale, higher values correspond again to better performance.
Projected and Confirmed Ratings
Projected ratings give home owners and builders an estimate of what a home’s efficiency will be like after construction or improvements, so that they may determine the most cost-effective route to improve a building’s efficiency. A confirmed rating, which indicates the home’s current efficiency, requires an inspection of the home from an energy rater. The home energy rater reviews the home to identify its energy characteristics, such as insulation levels, window efficiency, wall-to-window ratios, the heating and cooling system efficiency, the solar orientation of the home, and the water heating system. Performance testing, such as a blower door test for air leakage and duct leakage, is usually part of the rating.
Certified Home Energy Rating System (HERS) Rater
In order to provide certified Home Energy Ratings to rating clients such as builders or homeowners, individuals must become a Certified Home Energy Rating System (HERS) Rater. The process of becoming Certified includes the following:
- Training: Rater candidates must attend a HERS Rater training course presented by a RESNET Training Provider. The industry standard for HERS training is a 40 hour course that spans between 5 and 10 days although some trainers offer self paced online programs. Students learn the basics of building science, proper use of duct blaster and blower door equipment, RESNET standards, and mortgage and white tag related information. To successfully pass the Rater training, candidates must successfully complete two supervised training ratings, and pass the RESNET National Rater exam. There are no prerequisites for individuals who wish to obtain HERS Training and take the national rater test. However, HERS subject matter is difficult and the learning curve may be quicker for individuals who have a background in the construction or home inspection industry. The test is open book and open note, and students may use web resources to answer questions.
- Mentorship: After successful completion of the RESNET training course, the prospective rater must join a RESNET Rating Provider in order to be mentored through three Probationary ratings. The Probationary Rater shall complete these ratings under the supervision and direction of the Provider. Upon successful completion of all three Probationary ratings, and any other requirements outlined by the Provider, the individual will become a Certified Rater.
- Certification and Professional Development: After completing the Probationary Rater mentorship and becoming a Certified HERS Rater, the Rater then pays their annual dues to their Provider so that they may begin submitting Confirmed HERS ratings to the Provider for QA and so that they may produce reports for their builder or homeowner clients. Raters must then maintain their certification by obtaining 18 RESNET-approved Professional Development Hours (PDHs) every 3 years. PDHs may be earned by attending individual training sessions offered by RESNET Training Providers or attending the RESNET Building Performance Conference.
One of the most crucial components of the RESNET Home Energy Rating system is that quality assurance (QA) is integral to the process. RESNET Rating Providers must perform thorough quality assurance review of a minimum of 10% of rating files submitted for certification, and must perform on-site QA review on a minimum of 1% of ratings submitted by a Rater annually. This process ensures that ratings are conducted in accordance with RESNET standards and that the HERS Index and other certification documents generated by the rating file are accurate.
RESNET also provides annual QA review of Rating Providers to ensure that they are in compliance with RESNET standards.