Designing the zero net energy New American Homes
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While The New American Home’s design concepts change each year along with consumer trends, one theme remains consistent: maximum energy efficiency.
With the International Builders’ Show back as a live event last year, Pro Builder’s The New American Home and Pro Remodeler’s The New American Remodel were open to visitors in Orlando. Both homes continued the legacy of cutting-edge efficiency, achieving zero net energy goals and a host of green building certifications to serve as a showcase of innovation for builders.
“We’re always trying to raise the bar from year to year,” says Drew Smith, COO of Two Trails, the energy rater and sustainability consultant on both projects. On The New American Home, Smith wanted to achieve a minimal or even zero electrical bill. The finished project received a -15 HERS Index score.
To achieve that exceptional score, the home uses a 13-kW solar array and a highly efficient thermal shell. The exterior masonry walls use injected foam fill insulation and two layers of reflective wall insulation to get the exterior walls to around R-12. The unvented attic uses open-cell spray foam insulation, and all of the appliances are Energy Star–rated.
The home’s domestic hot water is provided by propane tankless water heaters from Rinnai with insulated hot-water lines utilized throughout the project to reduce heat loss and increase efficiency. “With gas being more affordable, it allows us to increase our efficiency on the electrical side if we don’t have that demand by using an electric water heater,” Smith says.
But while efficiency is a perennial feature of The New American Home, other aspects of its design were influenced by the post-pandemic trend of people spending more time working and relaxing at home, says Ed Binkley, the design director for architecture firm BSB Design, who led design of the project. Connecting indoor and outdoor spaces was a point of emphasis, for example, although it was a challenge given the home’s 50-by-125-foot lot — a size standard in many neighborhoods but smaller than a typical showcase home.
“It was really a perfect setup for the courtyard house,” Binkley says. “The main focus is every major room has a view or some kind of connection to the outdoors, that center courtyard.” A pool in that courtyard is enhanced with propane-fueled fire and water features. “It’s a pleasant thing to look at from almost any room in the house,” he says. “It’s not necessarily where you go to sit around and roast marshmallows, but it’s more of a visual kind of feature.” A roof deck on the third level includes a propane grill and fire pit where the owners can gather to enjoy extensive views of the surrounding community.
Binkley says the decision to use propane or gas in a home is usually one of the first conversations he has in the design process, and his firm frequently uses propane or gas for tankless recirculating water heaters, fireplaces, and cooking. The New American Home and New American Remodel both include a propane standby generator from Kohler to enhance resilience. “In Florida, with the hurricanes, there’s just too many times when we lose power down here,” he says. “If you can have a generator that’s automatic and services the most important items you need to maintain, then it’s always a consideration.”
Remodeling to zero net energy
Efficiency also took center stage at The New American Remodel, a midcentury modern home that doubled in size, where Smith and the design team were able to take the HERS Index from 115 when demolition started (meaning it was 15% less efficient than a baseline, code-built house) to a final score of -28. The New American Remodel home also obtained the most-efficient Emerald performance level in the National Green Building Standard.
“My vision for the 2022 New American Remodel was to really capture the essence of this midcentury modern home without taking away from the charm and beauty of the original house,” Phil Kean, owner of Phil Kean Designs, says in a project video. “The vision was to create a house that felt like it was original and yet has all of the modern conveniences, all of the modern technologies, all of the modern elements and parts that make what somebody would want today in a home work.” Those modern features include linear propane fireplaces, a pool with a propane heater, and a propane-fueled outdoor grill.
Many energy-efficiency techniques were shared between the two projects. Much of the remodeled home’s major energy uses are powered by propane, and the home has a 13-kW solar array with an insulation strategy similar to the new home’s. Both homes also use energy-recovery ventilators and dehumidification, which is very important in Florida, that turns on to dehumidify makeup air whenever the range hood goes on. In all, the remodeled home is expected to achieve extraordinarily low energy costs, projected at less than $250 a year.
Efficient domestic hot-water design
Both homes have luxury, multi-fixture shower systems with large water demands that required multiple tankless water heaters; The New American Remodel features five Bosch propane tankless units, including one at the guest house. “Tankless is definitely the way to go because you can always supply that ongoing demand,” Smith says. “You can’t do that with a tank water heater. When you run through that 60- or 80-gallon tank, you’ve got to wait for it to catch up. The wonderful thing about the tankless gas is they will keep up. They just keep running until you don’t need them.”
One recommendation Smith frequently makes is to locate water heaters as close to the center of the home or the point of use as possible to minimize plumbing run lengths. Often, that might mean putting one tankless unit on each side of the house. On The New American Remodel, the layout of the house dictated that the units would be located on the living room and bedroom side of the house, close to major hot-water usages.
With the propane tankless water heaters efficiently meeting the home’s domestic hot-water energy demand, The New American Remodel surpasses its zero net energy goals, serving as a showcase for how efficiency-focused remodeling can radically transform energy usage — even of old, inefficient existing homes.
Top photo: The New American Home’s roof deck includes a propane fire pit where the owners can gather to enjoy a beautiful vista of the surrounding community. Photo copyright Jeffrey A. Davis, courtesy Pro Builder Media.