Knowing a Home’s HERS Rating Makes Shopping for a New One Easier

Understanding Your Home's HERS Rating

Although an affordable mortgage payment is the major concern for new homebuyers, people are paying closer attention to what it will cost to heat and cool their new residence.  Whether they are in the market for an existing home or building or buying a new house, consumers can use HERS Ratings to make an informed decision before they buy.

HERS (Home Energy Rating System) is a computer-simulation program established in 2006 by the Residential Energy Services Network (RESNET), a national association of home energy raters and energy-efficiency mortgage lenders based in California. Using the HERS software, an independent certifier assesses a home’s predicted energy consumption rating it against an imaginary reference home of equal size under standard conditions.

HERS Index is Like MPG for Houses

The HERS Index Score is an energy-efficiency measurement comparable to the MPG rating of a motor vehicle except that the lower the score the better the energy efficiency.  A home with an Index Score of 70 is 30% more efficient than an average new home while a score of 130 indicates a home that is 30% less efficient than the average new home.

This short video explains why the HERS rating benefits homebuyers and homeowners.

Homeowners can use the HERS rating to explore their current home’s energy usage and home buyers can use it to comparison shop because homes with lower HERS scores are quieter, more comfortable, cost less to run and demand a higher selling price.

Inefficient homes frequently experience temperature fluctuation due to poorly performing heating and cooling systems, so maintaining overall comfort is more challenging and costly. Moisture and air infiltration can produce unhealthy living conditions.

Besides informing consumers about how a home performs energy-wise, a HERS rating provides consumers with a detailed report and cost/benefit analysis of the factors causing the rating and recommendations for modifications and specifications to improve energy-efficiency over the life-cycle of the home.

Good HERS Index Means Higher Resale Value

In addition, when a home receives a HERS energy-efficient certification, it raises resale value and differentiates it from other homes on the market.  For example, in a Portland, Oregon study, the non-profit group Earth Advantage found that certified existing homes sold for 30% more than non-certified counterparts in the six-county metropolitan Portland area.

New home buyers who purchase a HERS energy-rated home are eligible for an energy-efficient mortgage which offers buyers competitive rates and larger loans to finance energy efficiency upgrades that will lower costs and improve their HERS rating. A joint University of North Carolina and Institute for Market Transformation study determined that on average mortgage default risks were 32% lower for certified energy-efficient homes.

Moreover, there are often tax credits available for energy efficiency technology including water heaters, boilers, furnaces, air conditioning, heat pumps, windows, insulation, roofs and renewable energy installations.

Better Mortgages

Homeowners with an HERS rating who plan to make energy improvements on their existing home can qualify for an energy improvement mortgage, which accounts for the costs of the upgrades in the mortgage so buyers don’t have to worry about a larger down payment.

Conducting blower door tests and using equipment such as duct leakage testers, combustion analyzers and infrared cameras, HERS certifiers evaluate floors above unconditioned areas like cellars and garages, above and below grade exterior walls, attics, foundations, crawlspaces, ceilings, roofs, windows and doors, ductwork and vents, leaks in the heating and cooling distribution system, home air leakage, the HVAC and water heating systems and the thermostat.

Important considerations that can affect the HERS rating of a new home are the quality of windows and doors, the R-value of the insulation, the efficiency of the heating and cooling equipment, and improving the building envelope with a  air and moisture barrier.

An example of a high performance air and moisture barrier is DELTA®-VENT SA. Where building wraps can allow moisture to enter the walls and waste energy, DELTA®-VENT SA is fully adhered to prevent these problems.

Homebuyers who consider HERS ratings when shopping for new homes will make a more informed decision.


Dörken delivers innovative, high-performance air and moisture barriers for commercial and residential construction sold under the DELTA® brand name. A North American manufacturer based out of Beamsville, Ontario, Dörken Products, Inc. is a subsidiary of Ewald Dörken AG, a leading European developer and manufacturer of waterproofing and drainage products sold worldwide. Dörken is known for delivering premium products while providing educational programs and full technical support. For more information, call 1-888-4DELTA4 (433-5824) or visit