What Are Builders Doing to Increase Energy Efficiency?

Sustainability and Green Building
Published
This post has been updated.

Home builders can learn how to achieve low Home Energy Rating System (HERS) Index scores by looking closer at data points captured in energy modeling software to see what trends emerge.

Cy Kilbourn of Ekotrope analyzed all the homes registered in its database in 2019 and found that the most common HERS Index score was 58, and the majority of scores fell within a standard bell curve ranging between 45 and 80. Keep in mind, the lower the score, the more energy efficient the dwelling is compared to a 2006 code-built home.

One general industry trend confirmed by these data points is that homes with HERS Index scores below 50 tend to have smaller square footages of livable space, and multifamily units generally have lower scores because of this. Efficient building practices and features also play a role:

Heating equipment type:

  • Ground source heat pumps dominated the lower score ranges.
  • Homes with air source heat pumps ran the gamut on scores overall, but homes that scored between -20 and 5 (which is almost or even better than net zero energy) had mostly air source heat pumps.
  • Electric resistance heating (such as baseboards) was only found in houses that scored 75 or higher.
  • Homes that had scores between 25 and 70 mostly had traditional furnaces.

Heating and cooling efficiency:

  • Houses that ranged in scores on the lower end from 25 to 40 had Seasonal Energy Efficiency Ratios (SEER) of 17-24, while homes that had HERS Index scores of 45 and above had SEERs hovering at about 14.
  • For higher HERS scores in the 70-75 range, the Annual Fuel Utilization Efficiency (AFUE) was in the mid-80s, versus AFUEs of 90 and above for more efficient homes with HERS scores below 55.

Mechanical ventilation type (additional ventilation is key for tighter homes):

  • Homes with HERS scores of 40 and below almost exclusively have Energy Recovery Ventilators (ERVs) and Heat Recovery Ventilators (HRVs).
  • Homes with scores between 40 and 50 are more likely to have exhaust only
  • Houses with HERS scores between around 56 and 80 tend to have air cyclers.

Solar photovoltaics (PV):

  • On average, the lowest score without PV is in the low 40s.
  • Almost 100% of homes that scored 30 and below have solar PV.

Although there might not be a single formula to get the lowest HERS score, the good news is you have options. To increase energy efficiency, you may want to consider selecting heating and cooling equipment that has a high Coefficient of Performance (COP) and a high SEER, integrating mechanical ventilation, and incorporating renewable energy. Combining multiple efficient products and incorporating sound building science principles into early design and planning stages has the potential to make the building more efficient. As always, many of these choices depend on the client, the project’s geographic location, and local and state codes and regulations.

Trends like these can help builders get a sense of how newly constructed homes in the market have scored on the HERS Index based on various factors. Consider learning more about the HERS Index, and also exploring the value of third-party green certifications on your next build.

For more information about NAHB's sustainable and green building programs, contact Program Manager Anna Stern. And to stay current on the high-performance residential building sector, follow NAHB's Sustainability and Green Building team on Twitter.

Subscribe to NAHBNow

Log in or create account to subscribe to notifications of new posts.

Log in to subscribe

Latest from NAHBNow

Advocacy

May 22, 2025

House Approves Tax Bill with Key Housing and Business Provisions

By a vote of 215-214, the House early in the morning on May 22 narrowly passed the One Big Beautiful Bill Act, sweeping tax and domestic policy legislation that NAHB believes is very positive for small businesses, real estate and our members.

Economics | Indices

May 22, 2025

Income Growth Helps Mute Existing Affordability Constraints

Despite solid income gains and lower home prices, Americans still continue to face major housing affordability challenges, according to the latest data from the NAHB/Wells Fargo Cost of Housing Index (CHI). The CHI results from the first quarter of 2025 show that a family earning the nation’s median income of $104,200 needed 36% of its income to cover the mortgage payment on a median-priced new home. Low-income families, defined as those earning only 50% of median income, would have to spend 72% of their earnings to pay for the same new home.

View all

Latest Economic News

Economics

May 22, 2025

Existing Home Sales Fall in April

Despite the brief retreat in mortgage rates and increased supply, existing home sales dropped to 7-month low in April, according to the National Association of Realtors (NAR). This unexpected decline suggests buyers’ activity continues to be constrained by economic uncertainty and ongoing affordability challenges even with improved market conditions.

Economics

May 22, 2025

Income Growth Helps Mute Existing Affordability Constraints

Despite solid income gains and lower home prices, Americans still continue to face major housing affordability challenges, according to the latest data from the National Association of Home Builders (NAHB)/Wells Fargo Cost of Housing Index (CHI).

Economics

May 21, 2025

Gains for Multifamily Missing Middle over Last Year

The missing middle construction sector includes development of medium-density housing, such as townhouses, duplexes and other small multifamily properties.