Home Energy Rating System (HERS) for All Climates

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Building America recommends working with a Home Energy Rating System (HERS) professional, architect, or engineer early in the design process to help select and size materials and equipment. The building scientists can be especially helpful in right sizing heating and cooling equipment. By forming a relationship with a rater who later will inspect the construction site, designers can get valuable feedback about what works and what house features require more detailed information for the site supervisor and the trades. Find out more about HERS raters at www.natresnet.org.

The best use of a HERS rater involves working with your rater in creating your design. When following this path, the rater analyses your construction plans, in addition to at least one on-site inspection and test of the home. The plan review allows the home energy rater to view technical information such as orientation (if known), shading area, proposed equipment ratings, and insulation levels. The on-site test involves blower door testing. Results of these tests, along with inputs derived from the plan review, are entered into a computer simulation program to generate the HERS score and the home’s estimated annual energy costs, based on heating, cooling, and hot water heating requirements. Building America also recommends testing ducts for air leaks.

A HERS rating is an evaluation of the energy efficiency of a home, compared to a computer-simulated reference house (of the identical size and shape as the rated home) that meets minimum requirements of the International Energy Conservation Code (IECC). More information on the code can be found at www.energycodes.gov. The HERS rating results in a score between 0 and 100, with the reference home assigned a score of 80. From the 80-point level, each 1 point increase in the HERS score results in a 5 percent reduction in heating, cooling, and hot water energy usage (compared to the reference house). An ENERGY STAR qualified new home, which is required to be 30% more efficient, must attain a HERS score of at least 86. However, ENERGY STAR criteria are currently under revision.

Your HERS rater can be a tremendous resource in the design phase. Raters who are trained in building science may help to solve construction problems. One important job your rater can help with is to work with the mechanical contractor to correctly size heating/cooling equipment, perform room-by-room calculations to determine the supply air needed for each room, and work with the mechanical contractor on duct sizes and lay out. This is likely to eliminate callbacks due to comfort complaints and can save substantial money by right-sizing the heating and cooling equipment. During the design stage, the rater can suggest alternatives to attain desired performance levels in the areas of energy, comfort, durability, and health.

Selecting a HERS rater is much like selecting any other professional services provider, such as an architect, accountant, or engineer. Be sure you are comfortable with the rater’s communication skills, experience, training, and references before making a selection.

For more information, please visit Building America or download the full reports below:

Cold and Very Cold Climates

Hot-Dry and Mixed-Dry Climates

Hot and Humid Climates

Marine Climates

Mixed-Humid Climates