DOE Zero Energy Ready Homes

Homes That Leading Builders Want for Their Families

September 04, 2017
Fall 2017
A version of this article appears in the Fall 2017 issue of Home Energy Magazine.
Click here to read more articles about Energy Efficiency Programs

Building homes that live better, work better, last better, and are so energy efficient that homeowners have zero energy bills over the course of the year is a goal of the U.S. Department of Energy (DOE)’s Zero Energy Ready (ZER) Home program.

Since 2013, builders around the country have certified more than 1,170 homes to the high-performance criteria of this program. Each year DOE recognizes the best innovators among these builders with the DOE Housing Innovation Awards. This year’s winners will be announced at an awards event taking place at the Energy & Environmental Building Alliance High-Performance Home Summit October 10–12, 2017, in Atlanta, Georgia. A total of 25 builders are expected to take home awards; grand award winners in each of the five competition categories will be revealed at the conference.

“Housing Innovation Award winners represent the very best in innovation on the path to ZER homes. These are the kind of high-quality homes that builders would choose for themselves and their own families,” said program manager and chief architect Sam Rashkin. “Last year’s award season was our most competitive, and we expect this year the bar will be raised again. Zero Energy Ready Home builders already represent the top 1% of all home builders in the country, so you are competing against the best of the best. ”

Reclaimed wood and old metal roofing provide a unique exterior for this ultraefficient urban infill home by Dwell Development of Seattle, which won a grand award in the custom spec category in DOE’s 2016 Housing Innovation Awards. (Dwell Development)

United Way of Long Island Housing Development Corporation was a grand winner in the affordable homes category of the DOE 2016 Housing Innovation Awards for this super-efficient traditional two-story 1,890 ft² home. (United Way of Long Island)

Builders participating in the program represent every climate zone in the country, and DOE ZER-certified homes can be found in 34 states. They represent the full spectrum of the U.S. construction industry—from affordable to production to custom homes, and from single-family houses to duplexes to five-story multifamily buildings. A few retrofit projects have also managed to meet the criteria.

Every DOE ZER-certified home also meets the Energy Star certified-home standard, as well as the requirements of the EPA Indoor airPLUS program and the hot-water distribution requirements of the WaterSense program. Homes must also meet the insulation requirements of the 2012 International Energy Conservation Code. If the home has HVAC ducts, they must be installed within the conditioned space. Appliances, exhaust fans, ceiling fans, and most of the lighting must be Energy Star qualified. The DOE ZER Home program also requires homes to have solar-electric panels installed or, at a minimum, to have the conduit and electrical panel space in place for future PV installation, if the home is in a location appropriate for solar power. As the name implies, the goal is to produce zero energy ready homes. Homes are constructed to be so energy efficient that, with a reasonable number of PV panels (about what would fit comfortably on the south-facing roof), the home can produce as much electricity as it uses in a year. Of the 123 homes to win awards or to receive honorable mentions in past year’s Housing Innovation Awards, about two-thirds were sold with the PV panels already installed.

Solar panels help a DOE ZER home achieve a coveted zero on the Home Energy Rating System (HERS) index. Typical new homes score about 100; the average HERS score for older homes is about 130. The DOE ZER Home program doesn’t require that all homes achieve a HERS score of zero, but it does require builders to meet a target HERS score that is unique to their house if they are using the performance path to qualify.

Many DOE ZER-certified homes score below 40. Among past years’ Housing Innovation Award winners and honorable mentions, 112 of the 123 homes achieved a HERS 50 or lower. Of these homes, 46 achieved a HERS 10 or lower; and 39 achieved a HERS 0 or lower. Eighteen of the builders actually achieved HERS scores of minus 5 or lower. With HERS scores this low, the homes are producing enough electricity to power the home and an electric car or two.

Two Qualifying Paths

The DOE ZER Home program provides builders with two paths to qualify: a prescriptive path that includes the mandatory requirements mentioned above as well as a specific set of climate-specific measures; and a performance path that includes the same mandatory requirements but allows builders to make trade-offs in some of their construction choices as long as they meet a target HERS score. Builders determine their target HERS score by modeling a home that is the same size and shape as the one they hope to build and that is designed to meet the program’s prescriptive requirements for the desired location. The modeling software (typically REM/Rate), is run by a HERS rater and gives a HERS score that serves as a performance target. The builder can make trade-offs in the design of the actual home to meet that target.

This performance target approach has encouraged builders to experiment. Wall construction has ranged from traditional 2 x 4 and 2 x 6 studs, often with advanced framing techniques, to structural insulated panels (SIPs), insulating concrete forms (ICFs), insulated concrete panel systems, aerated concrete, and double walls. These walls have been constructed over every kind of foundation, from slabs, to crawl spaces, to full basements, to elevated pier structures. Insulation types have included batt, blown-in, and board fiberglass, cellulose, mineral wool, and polyisocyanurate, as well as open- and closed-cell spray foam, and even wool and shredded denim.

The low heating and cooling loads of these homes have encouraged even greater experimentation. Home heating systems have included traditional high-efficiency gas furnaces; passive heating; central air-source, air-to-water, and ground-source heat pumps; ductless and ducted mini-split heat pumps; hydrocoils in central air handlers; and radiant floor loops using hot water from solar water heaters, on-demand gas boilers, and ground-source heat pumps as the heat source. Cooling sources have included central compression cooling, heat pumps, and night ventilation cooling, sometimes with supplemental dehumidification. Many homes have energy recovery ventilators (ERVs) or heat recovery ventila­tors (HRVs), while some use run-time ventilation with timered dampers tied to central HVAC fans and some use exhaust fans. Water heaters may be electric, gas, or propane tank or tankless; heat pump water heaters; or combination systems that use gas boilers for heat and hot water. Many systems include solar-thermal heating systems or ground source heat pumps equipped with desuperheaters to provide either the primary hot-water source or preheating.

Buyers snapped up the 57 townhomes Thrive Home Builders is constructing in a Denver suburb. The project was cowinner of a grand award in the multifamily category of the DOE 2016 Housing Innovation Awards. (Thrive Home Builders)

Philgreen Construction’s DOE ZER solar-topped townhomes in Fort Collins, Colorado, perform so well that builder Dave Phillips hands out copies of utility bills showing that many homeowners carry a credit from the utility company rather than owing money. (Philgreen Construction)

Zero Energy = Zero Electric Bills

Homeowners rave about their low utility bills. “I’ve been living in the Midwest for over 35 years, and this is the first home I’ve lived in that hasn’t cost me an arm and a leg to heat during the winter,” said the owner of a home built by award winner Amaris Homes in Apple Valley, Minnesota. Fourteen of the 2016 winners had utility bills of less than $15/month; seven of these homeowners had calculated average monthly bills below $0/month. In other words, most months they are getting a sizable credit from their electric utility. “The utilities in homes we lived in before ranged from $150 to $300 a month. Last month, our utility bill was $11,” said the owner of a home built by Philgreen Construction in Fort Collins, Colorado. The utility bills are so impressive that Philgreen Construction uses them like marketing fliers, handing out examples of current homeowners’ utility bills at open houses.

One would expect that such high-performance homes would cost more to build, but that is not always the case. “In most cases, we find that building to zero energy ready levels is not a significant added cost,” said Kendall Carpenter of AquaZephyr, LLC, in Ithaca, New York, which has built and certified single-family detached homes, duplexes, and a four-story apartment building through the program. Josh Anderson, of Element Design Build, agrees. “The energy consumption of new houses can be reduced by as much as 40% with little or no impact on the cost of construction,” said Anderson, whose company built and certified the National Association of Home Builder’s New American Home for 2016 in Henderson, Nevada.

“Over the last decade, we’ve developed practices that allow us to build net zero energy homes for the same price as traditionally constructed homes. Sometimes, we are able to build them for even less,” said Ted Clifton, a custom builder whose company, TC Legend Homes, has worked with the DOE program since 2013 to build nine certified homes in Seattle and Bellingham, Washington, often costing around $120 per square foot, not counting land. Dow Perry said the award-winning 3,021-ft2 HERS 45 DOE ZER custom home he constructed in Prattville, Alabama, cost no more per square foot than a just-to-code home. Dave Jones, of Revival Homes, used preinsulated concrete and SIP wall panels to construct a three-bedroom, two-bath, two-story DOE ZER home in New Hartford, Connecticut, “on a modest budget that most people can afford.” “People just don’t believe you can actually build a house like this for about the same cost as essentially any other house,” said the homeowner, who paid construction costs of $135 per square foot, including the PV system (but not including the land, well, or septic) for the highly efficient home, and is being rewarded with utility bills averaging minus $37 per month.

Mandalay Homes won a grand award in the DOE 2016 Housing Innovation Awards production homes category for this single-story in Prescott, Arizona. (Mandalay Homes)

White metal roofing and siding plus a continuous double layer of rigid-foam insulation keep heat from penetrating through the walls and roof of this Athens, Georgia, bungalow by Imery & Co. (Imery & Co.)

Homes that Pay Back from Day One

Some builders in the program point out to homeowners that when lifecycle costs are considered, the true cost of ownership is often less for Zero Energy Ready homes than for homes built to just meet code, on a monthly basis. Steve Bostic, who constructs DOE ZER-certified homes through his Amerisips and InsulSteel Enclosures companies in Charleston, South Carolina, likes to walk prospective buyers through the initial and lifetime costs of their home. He shows them that while some higher-performance equipment may have higher upfront costs, when those costs are worked into a 30-year mortgage, the increase in monthly payments is more than offset by the reduction in monthly energy bills, resulting in a cost savings to the homeowner from day one. “We have 3,000-ft2 homes that have monthly electric bills of $15 or $20,” said Bostic.

Many builders implement trade-offs to keep initial costs on par with just-to-code homes. For example, more insulation and higher R-value windows may cost more, but they may help cut the heating and cooling loads enough to justify installing a smaller HVAC system. “We have created spreadsheets that measure virtually everything we do and enable us to compare the results of one strategy against another, so that we can give our customers the very best advice on what is and is not cost-effective,” said designer and builder Ted Clifton, owner of Clifton View Homes and Zero Energy Plans, in Coupeville, Washington. “Our returns are higher, with less risk, than is usually achieved through the stock market. We should be licensed as investment counselors!”

Clifton and his son, Ted Clifton of TC Legend Homes, both use the concrete foundation slab as the finished flooring surface of the first floors in their homes by sealing and staining the concrete. This saves on the cost of hardwood flooring and also enhances the slab’s ability to serve as a passive-solar heat sink. Passive-solar design elements are used by many builders in the program to cut heating and cooling loads even more.

“When a net zero energy home can be built at a cost on par with traditional construction, everyone wins,” said Ted Clifton Jr. “We are helping to usher in a new era of green construction in which homeowners don’t have to choose between cutting-edge efficiency and staying on budget.”

The energy security benefits of ZER construction are not lost on homeowners. “My energy bills, including transportation [for an electric car], were $5 [per month in the winter] and now have gone negative in the spring, and they will continue to earn money in the summer,” said the owner of a home by Philgreen Construction in Fort Collins, Colorado. “I won’t have to worry about increasing energy bills in the future because I am more in control of both my energy use and production.”

The master bedroom inside a home by Dwell Development of Seattle, which won a grand award in the custom spec category in DOE’s 2016 Housing Innovation Awards. (Dwell Development)

Comfort and Health

While zero energy bills are certainly a big plus, consumers have several other reasons to love DOE ZER homes. Listen to what they have to say:

“Our lives are healthier owing to the great effort the builders have gone to, to eliminate or minimize harmful materials during construction” (owner of a custom home by Amaris Homes in Minnesota).

“While our prior home was entirely remodeled and rebuilt as energy efficiently as possible, the increased comfort level and more even indoor temperatures are noticeably better in the ZER home. The ICF construction also significantly reduced the noise level inside the home” (owner of a home built by Charis Homes in Canton, Ohio).

“While our power bill is lower, our comfort, our well-being, and our quality of life are all much, much higher” (owner of a home built by Addison Homes in Greenville, South Carolina).

“As soon as you walk into this house, you can tell it’s sound, it’s airtight. You feel like you’re wrapped in 100 wool blankets. It’s so warm you would never know that it’s been below zero this past few weeks” (owner of a 2016 grand award winner built by BPC Green in western Connecticut).

“Living very near a military practice airfield, we’ve noticed the tight, triple-paned windows dramatically reduce any exterior noise” (owner of a DOE ZER home built by Clifton View Homes in western Washington State).

“We wanted to do something that was right for the world we were leaving to our kids and our grandkids” (owners of a DOE ZER home built by Glastonbury Housesmith in South Glastonbury, Connecticut).

“We were attracted to the home by the fact that it had a complete high-performance package—high energy efficiency, high water efficiency, air filtration for indoor air quality” (owner of a ZER-certified home by High Performance Homes in Gettysburg, Pennsylvania).

Many homeowners appreciate the air quality improvements provided by ZER-certified homes, which meet the requirements of the EPA Indoor airPLUS program, as noted above. “My previous apartment made my allergies terrible. Since moving in, they have gotten much better,” said the owner of a townhome by Thrive Home Builders in Denver, Colorado. “There is a noticeable difference in air quality inside our home, especially during allergy season. For a family of allergy sufferers, this is invaluable,” said the owner of a home built by Greenhill Contracting in Esopus, New York. Dave Radlman, founder of Heirloom Design in Atlanta, Georgia, who lives in the first DOE ZER home his company built, notes that his wife, a longtime asthma sufferer, no longer has to take daily medications.

Builders and homeowners alike have been blown away by the drastic differences between living in a high-performance home, as compared to a home that meets minimum code requirements. Enthusiastic homeowners have also become great advocates for the program.

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Get more information on DOE’s Zero Energy Ready (ZER) Home program.

“What really tells us we are doing well is that our customers are going out of their way to help us sell homes,” said Tim Lowndes, founder of Charles Thomas Homes, in Omaha, Nebraska.

A farmworker living in the first apartment building certified through the DOE ZER program in Woodland, California, describes life before and after moving into the family’s new home. “Before, my family and I lived in a two-bedroom apartment that had troubles—with heat, the plumbing, and battling with cockroaches. It was hard dealing with our children’s medical issues . . . and coming home to an apartment that we dreaded living in. But things took a 180 when we moved into Mutual Housing at Spring Lake. We now live in a new four-bedroom apartment and we love it! The day we moved in, my seven-year-old son ran inside, yelling, ‘I love my house! I love my house!’”

Theresa Gilbride is an energy policy and economics scientist at Pacific Northwest National Laboratory.

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