Finishing touches are being placed on Magnolia House, a quaint, white clapboard two-story, three-bedroom residence located off Walnut Avenue in downtown Fayetteville. Architectural designer Michael Cockram built the 1,780-square-foot home, which he will soon list for sale.
“This kitchen opens up to the living and dining room area,” Cockram said, providing a tour. “There’s an open stairway that’s alongside the living area.”
Cockram walks up the spalted pine slab stairway to the main bedroom overlooking a certified urban wildlife habitat filled with paw paw, oak, cedar, and magnolia trees.
“Gives you the feeling of being secluded in the woods here,” he said, peering out into the forest.
Cockram’s firm, Bowerbird Design LLC, has long specialized in energy-efficient residential and commercial construction projects. He’s now focused on passive house construction.
“I had friends and colleagues who started getting interested in passive house certification, so I started looking at that,” he said. “I’m also a freelance architectural writer and have written several articles on passive houses. I’ve had this interest for many years, but I haven’t had the opportunity until recently to use the passive house techniques.”
Cameron Caja, a certified passive house consultant with Austin-based engineering firm Positive Energy, collaborated with Cockram on Magnolia House. Caja said today’s passive house strict performance-based standards originated 25 years ago in Germany.
“By a gentleman named Wolfgang Feist, who was a doctor,” Caja said. “He was very interested in energy efficiency and increasing comfort standards for people in their homes. And in Europe, energy prices have remained high, so there was always an economic incentive for people to invest a little more money in the envelope, in the shell of their home, and then reap savings over the entire life of that home by having reduced energy costs.”
Caja said a certified passive house consumes 20 percent of the energy used by a conventional code-built house.
“The components to build a home are essentially the same between the code-built house and a passive house,” Caja said. “So we’re still building the walls out of 2x4 or 2x6 wood studs, we’re still applying drywall to the inside of the home. Passive house construction methods are essentially the same. What we’ve done is we have just increased the amount of insulation within those assemblies, and we have worked very, very hard to make sure that it is an airtight envelope. That is one of the biggest differences between a passive house and conventional construction.”
The walls are stuffed with fiberglass batting 5 1/2 inches deep, clad with wood sheathing, then covered with XPS foam board insulation.
“And on top of that foam insulation, we applied a wood furring strip that gives us an air gap between the cladding of the home and that insulation,” Caja said. “So that if any wind-driven rain were to get behind the cladding, the lap siding, there’s an air gap where that water can drain. It’s not held against the home where it’s going to cause swelling, mold, or other kinds of durability issues that a lot of our homes around this area do suffer from.”
Next, the house envelope, or shell, must be made airtight.
“For a passive house to have high levels of control over the interior living environment, you need to ensure that it is an airtight envelope,” Caja said. “I can say the best, easiest, and most economic way to ensure an airtight envelope is to use high-performance tape, which we import from Germany. We apply that to all of the seams. We will make sure that all of those potential gaps are sealed.”
Rather than installing an electric HVAC system, Magnolia House has a mini-split heat pump, one unit inside and another outside, that work to both heat and cool the home.
“It’s not actually generating any heat,” Caja said. “It’s simply pulling heat from the outside when we need it and injecting it into the house. And when we need to cool, it’s taking the heat from inside the house and injecting it outside of the house, so it is extraordinarily more efficient than a conventional HVAC system."
The home also features a heat pump water heater, heat pump clothes dryer, energy-star-rated appliances, LED lighting, and triple-glazed windows.
Because Magnolia House is airtight, fresh filtered ventilated air is supplied by an ERV system, an energy recovery ventilator, discreetly installed in a downstairs closet.
“This one in particular is built by a company named Broan,” Caja said. “It is their AI series, and it’s able to provide at least 18 cubic feet per minute of fresh air for every occupant in the home 24 hours a day, seven days a week.”
Despite hot, humid conditions outside, the quiet interior of Magnolia House feels comfortably cool and dry. Caja said the poured, finished, insulated concrete floor acts as a thermal sink. The exterior of the house is clad in fire- and rot-resistant fiber cement siding. The sloped roof is covered with durable corrugated metal standing seam panels, in addition to a flat green roof.
“This house is on track to be the first certified passive house in the state of Arkansas,” he said. “The certification has not yet been bestowed upon this project because they require extensive third-party testing at completion of the home.”
Once certified, Caja said, Magnolia House will be listed on a national database for both residential and commercial passive-built structures.
“You see a lot of these projects happening in the northeastern U.S. and in California,” Caja said. “New York has adopted a standard where all multifamily residences must be built to a passive house standard because they recognize the need for reducing energy consumption within the city and increasing durability and resiliency through extreme weather events.”
Magnolia House general contractor Alex Munson with Munson Construction said she’s now a passive house enthusiast.
“I’m coming up on 18 years of business, and so I’ve built homes all the way from 200-square-foot tiny homes all the way up to 4,000-square-foot homes,” she said. “I generally call myself an ultra-custom builder. I can build any plan, any design, but I do desire to stay in the passive house energy efficiency range, and we’ll definitely be using these practices on all my homes.”
Passive home construction principles can be applied to building renovations as well, she said.
“You absolutely can,” Munson said. “It can get trickier, but we can fit into any budget. We don’t have to go all the way to a passive house standard every time, but we can still implement a lot of those practices and help with energy efficiency along the way.”
Ryan Cloud, a junior partner with Munson Construction, said it’s been a big learning curve building this place.
“So a challenge we’ve had is educating our subcontractors and tradesmen about how we want to build this new standard,” Cloud said. “And I keep telling them that over the next ten, twenty years hopefully every house is going to be built like this.”
Cockram declined to disclose construction costs for Magnolia House, but said the sale price will be $650,000. A new passive house reportedly can cost between five to 20 percent more than a conventional home, but those costs are eventually recovered from operational savings.
As for affordable passive housing? In 2015, the U.S. Department of Housing and Urban Development began to offer developers low-income housing tax credits to subsidize passive housing. Today, around half of all passive house projects under construction in the U.S. are reportedly affordable housing developments.
Michael Cockram is hosting an open house for Magnolia House on Sunday, July 21st, from 2 to 4 p.m., located near the intersection of Walnut Avenue and East Johnson Street in Fayetteville. Watch for the signs.
