May 6, 2014 in City
Passive house in Elk features energy-efficient construction
Quiet permeates the interior of Pat and Robin Rickey’s new passive house in Elk, built 200 feet from Highway 2.
To let visitors hear beyond 20-inch thick walls, Robin Rickey cracked a window to the faint roar of a passing semitrailer.
“Noise, no noise – love it,” she said, while closing the bedroom window. “You get into your own controlled environment here, and when I go outside, all of a sudden the highway sounds noisier.”
The couple moved two weeks ago into the 1,500-square-foot, single-story home that their architect and builder call the first passive house constructed in the Inland Northwest. The home’s highly insulated, airtight design minimizes heat and energy loss; they expect to save significantly in heating and cooling costs.
Outside, the home appears commonplace, with gray conventional lap siding and white trim. But its design and construction differ from conventional and “green” building methods, said Gavin Tenold, the contractor.
Triple-pane windows draw plenty of natural light but have super-insulating properties. The walls and roof have fiberglass insulation four times the volume of a conventional home, and they’re air-sealed like an airplane, Tenold said. There is 12 inches of expanded polystyrene foam under the foundation.
Lacking a furnace or air conditioner, it’s designed to stay at an inside temperature close to 70 degrees year-round.
“It’s just super insulated, super airtight and constantly ventilated,” Tenold said. “Passive house construction is more concerned about total energy consumption per house.”
Popular in Germany and Belgium, passive house construction is slowly gaining attention in the U.S. The Passive House Institute U.S. has certified nearly 100 homes in the nation since forming as a nonprofit in 2007. “Passive” in the name refers to gaining energy savings of 60 to 70 percent – and up to 90 percent savings in heating cost – without more “active” furnace and air conditioners, large geothermal systems or elaborate solar panels.
Instead, energy losses are minimized and gains are maximized – an approach boosted by using sophisticated software to calculate such factors as a region’s climate, dew point and internal heat sources ranging from body temperature to appliances.
“Modern living creates heat; it’s important that we capture it,” Tenold said.
The home’s energy-saving windows are crucial. They were manufactured in Canada with an R7 rating, “tech talk for how thick is the blanket,” Tenold said. “Those windows harvest more heat coming in than they let out.”
The home is so airtight that fresh outdoor air is brought in mechanically by an energy recovery ventilator system that supplies the constantly tempered, filtered air inside. The ventilator, about the size of a cat carrier, is suspended from the ceiling of a utility closet near the home’s hot water tank.
“The entire air volume of the home is being replaced every three hours, so musty is not a concern,” Tenold said.
Small, round vents in the ceiling are scattered through the house to exchange air and prevent formation of mold. As part of the ventilator system, piping is buried at about a 5-foot depth surrounding the house to “temper” outdoor air being drawn in to reach the more moderate temperatures beneath the ground.
“We’re prewarming the outdoor air into the air exchanger,” Tenold said. The method alternatively helps cool the air on hot days, although it isn’t a typical geothermal system that’s built for some homes today, he said. A small, ductless heat pump inside the home in a central hallway is available for minimal heating or cooling needs.
The Rickeys hadn’t heard of a passive house until they approached Spokane architect Sam Rodell about building an energy-efficient home to take them through their retirement years. Pat Rickey is 55, and his wife is 52.
“Sam told us, ‘If you’re really interested in energy savings, you should consider a passive house,’ ” Robin Rickey said. “After researching it, I couldn’t find anything negative.”
Rodell, who designed the home, and Tenold, owner of Pura Vida Homes, are both certified passive house consultants through the institute. The house’s open floor plan has a great room leading into a large kitchen with a side dining area, as well as a small den near the front door. The front of the home faces south to maximize absorption of solar heat in the winter.
“They call the house the envelope, so you can tell the difference,” Robin said, as she guided visitors into an attached, single-car garage, the only part of the house built conventionally. A rush of cold air greeted guests.
The couple can crack a window or prop open the door to enjoy milder days, and the ventilator can be shut off. The institute estimates that passive house construction costs about 10 percent more than conventionally built residences in the U.S., but the amount varies by climate and project scope.
While the couple didn’t disclose building costs, Robin Rickey said they expect any added expense to be offset long term by lower energy bills.
Also, she said, their costs didn’t include paying for a furnace with elaborate ductwork, but rather small, less expensive mechanical systems.
“It lives so nice,” Robin said. “It’s so quiet.”