Energy-Efficient Features in New Homes, Explained

The features that move the power bill most are air sealing, insulation, good windows, a right-sized heat pump, tight ductwork and an efficient water heater. A HERS score sums it up: lower is better, and a standard new home usually scores well below a typical older home.

What are energy efficient features in a home?

The ones that matter most, roughly in order of impact:

• Air sealing. Closing the gaps around pipes, wires, windows and the attic. Leaks waste heated and cooled air.
• Insulation. In the attic, walls and floors or crawl space.
• Windows. Low U-factor and the right solar heat gain for the climate.
• A right-sized heat pump. Sized with a load calculation, not by square footage.
• Tight ductwork. Ducts sealed and inside or well insulated.
• An efficient water heater. The DOE says heat pump water heaters can be two to three times more efficient than conventional electric ones, if installed in the right space.
• ENERGY STAR appliances and lighting.

Buyers want these. In NAHB's 2024 survey, ENERGY STAR windows were rated essential or desirable by 83% of buyers, and ENERGY STAR appliances by 80%.

Are newer houses more energy efficient?

Generally, yes. The clearest measure is the HERS Index from RESNET, the nonprofit that created it. A home built to the 2004/2006 energy code scores 100. Lower scores mean a more efficient home.

RESNET's consumer guide puts standard new homes at roughly 85 to 100, and typical existing homes above 100. A home scoring about 55 is about 45% more efficient than the 100 reference home. Certified HERS raters inspect and test homes during and after construction to produce the score.

Ask the builder whether the home has a HERS score, and what it is.

Is .27 a good U factor for windows?

For North Carolina's climate, it's good. U-factor measures how well a window keeps heat from passing through it, and lower is better.

ENERGY STAR's version 7 criteria set maximum U-factors by climate zone: 0.22 in the Northern zone, 0.25 in North-Central, 0.28 in South-Central and 0.32 in Southern. A 0.27 window meets the South-Central and Southern limits but not the two northern zones. ENERGY STAR's site has a climate zone lookup if you want to check your county.

Look at the solar heat gain coefficient too. In warm zones, ENERGY STAR caps it at 0.23 so windows let in less summer heat.

Where the real savings come from

On the job sites I worked, the difference between an efficient house and a leaky one was rarely one big product. It was a lot of small, careful details: sealed penetrations, insulation installed without gaps, ducts that were actually connected and sealed. That's why third-party testing like a HERS rating is useful. It measures the result, not the brochure.

Questions to ask about efficiency

• Does the home have a HERS score? What is it?
• What type of heat pump and water heater are included, and how efficient are they?
• Are the windows ENERGY STAR certified for this climate zone?
• Where are the ducts, and are they sealed and tested?
• Was a load calculation done for the HVAC?

Who's writing this. I sell new homes for D.R. Horton at Collins Ridge in Hillsborough, so I represent the builder, not you. This guide is general education from my years on job sites and in sales. It isn't legal, tax or lending advice, and it doesn't describe any specific home, price or incentive. Check the sources linked below, and talk with your own lender, agent or attorney before you decide.