Bill Owens has been closely involved with the green building movement for more than two decades.
As a highly respected remodeler and active member in the leadership of the National Association of Home Builders, Owens has kept himself on the leading edge of energy-efficient construction technologies. So it was only natural that when he remodeled his own “forever home,” Owens designed the home to be zero energy ready, with a predicted Home Energy Rating System (HERS) Index rating under 30.
Owens is president of Owens Construction, a design-build remodeling firm in Worthington, Ohio, but his new home is a renovation of a 1970s mountain chalet outside of Flagstaff, Arizona. Contrary to the common perception of Arizona, the home is in a dry, high mountain desert environment at 7,000 feet of altitude, so it experiences extreme temperatures and an average of 100 inches of precipitation each year, mainly in snow.
That climate, combined with the home’s remote, semi-rural location, led to Owens busting another common perception — that zero energy homes must be all-electric. In fact, to achieve the comfort, resilience, and efficiency Owens had in mind for his dream home, going dual fuel with propane created an ideal energy solution.
Ultra-efficient technologies and materials
The project, which was also Professional Remodeler’s 2019 Model ReModel, includes many of the technology and building material hallmarks of modern ultra-efficient homes.
Owens used continuous 2-inch foam insulation on the outside of the house, along with a reflective barrier that reduces heat flow. In remodeling a home with existing 2×4 construction, the team used a combination of open-cell and closed-cell spray foam insulation. That included 4–5 inches of closed-cell spray foam around the existing crawl space and about 8 inches of spray foam in the attic to achieve close to an R-50 insulation value. He went back to pay special attention to reduce air infiltration around windows and used energy-recovery ventilators to provide efficient ventilation for a home with about 1 1/2 air changes per hour.
With a home that well-insulated, a high-efficiency mini-split heat pump system can handle the heating load in moderately cold conditions. But temperatures on the mountain can drop as low as -30 degrees Fahrenheit. Plus, Owens didn’t want his standby generator to be huge enough to run all the heat pumps during an outage. A hybrid heating solution with Goodman propane furnaces for the first floor and crawl space was an ideal solution.
“I just didn’t want the house freezing up on those cold nights,” Owens says. The crawl space furnace also heats up the hard floors above the crawl space, which are necessary in the dusty Arizona environment.
With backup propane heating in place, Owens could install a right-sized propane standby generator to handle the electrical needs of the furnaces, water pumps, refrigerator, and smart home features such as the smart water valve protecting against leaks.
“We’re literally at the end of the grid,” Owens says. “I am the last house on about 2 miles of electric overhead running through a national forest. If a big snow storm takes down a tree, I could be affected. I’m pretty low on the web to come back and get picked up again.”
Tankless water heating helps achieve green rating
Another feature that lends to both the low HERS rating and the lower load on the generator is a Navien propane tankless water heater. “The Navien was an easy choice just because we were trying to get a robust NGBS Green rating out of it,” Owens says. “There’s no electric unit out there that’ll keep up a whole house. Plus, it’s fairly frequent that we’re out of town, so we just didn’t want any [hot water] storage in there.” The tankless unit includes a programmable recirculation loop to minimize wasted cold water dumped down the drain in a state where water is precious.
In addition to energy-efficiency features, propane fuels several of the home’s most appealing lifestyle amenities. Owens plans to install a propane fire feature on the enclosed porch, a safer approach than open wood fires in a state with frequent fire restrictions and a site bordering a national forest. The home will also have propane cooking, both on an outdoor grill and on the kitchen cooktop.
“I like induction, but I don’t like it nearly as much as the propane,” Owens says. “I’ve checked with our energy rater, and he basically said that you get such a clean-burning fuel with propane that that’s not considered a detriment if you have the exhaust hood. It doesn’t work against you on the points for the green rating.”
Building to zero energy standards does come with a higher cost, Owens says, but the payback comes both in long-term energy cost savings and immediate comfort improvements. “This house is so tight that we don’t notice when the wind’s just howling or when we’re getting huge temperature swings out there,” he says.
The experience has also bolstered Owens’ support for dual-fuel homes with both electricity and natural gas or propane. Trying to run his home purely on solar and battery backup, in a state with disincentives for solar installations, would have been cost-prohibitive. “In a fairly severe environment or environments that are enough away from the grid, there is no perfect panacea with just one energy source,” he says.
Owens spoke alongside David Knight, an engineer from Monterey Energy Group, and Matt Evans, a certified home energy rater with Newport Ventures, in a January Propane Presents Technology Series webinar about zero net energy (ZNE). Check out the webinar to learn more about the latest in ZNE building trends.