The First Passive House EnerPHit Retrofit in North America

Paul checked it out. He was impressed. The Passive House in the Woods had sustainable systems that included a super-insulated, tight shell. “Many sustainable approaches to construction focus on active, expensive technologies, like geothermal ground loops, solar photovoltaics, and solar thermal,” he says. “These systems are fantastic in their own right, but will ultimately break or become obsolete. Insulation, on the other hand, is durable and long-lasting.” 

The Brazelton's talked with TE Studio about whether a Passive House approach would work on their home. The answer was yes. They began planning an addition with a deep energy retrofit(or whole house efficiency makeover). They also considered other strategies, including high-performance German windows, an advanced heat recovery ventilator, and wrapping the house with a thick layer of insulation.

Beneath the finished hardwood floors are 229mm, EPS insulation (0,035) and a polyethylene membrane that serves as a vapor barrier and airtightness layer (sealed airtight at joints and protrusions). A whole-house heat recovery ventilation system with an efficiency rating of more than 90 percent provides fresh air all day, every day. The existing in-floor heating system was recycled and extended to heat the home. The same boiler delivers domestic hot water.

A mini-split air conditioner was later installed to provide on-demand cooling and dehumidification. “When we first rebuilt the home and moved in,” Brazelton says, “we didn’t consider how hot it gets in the summer. The house was built to keep us warm in the winter, but it’s also a solar oven. Without shading from trees or exterior blinds, the house gets crazy hot on summer days. The mini-split, on the second floor at the top of the stairs, keeps the upper level at a comfortable 70 degrees.”

While the chimney was an integral component of the house’s façade, it created a backdraft. An open flame fireplace from the early 1900s was also in conflict with a 21st-century high-performance house. To resolve this challenge, the Brazeltons had the original brick chimney torn off and replaced with a replica chimney clad in stone veneer. The house is clad in Hardie lap siding and has triple-pane German windows. 

“Initially we didn’t include solar because we couldn’t afford it,” Brazelton says. “Now that we have solar, we do wish we would have installed it during the remodel. The house is very electricity-centric. The hot water heater is natural gas. But the oven, clothes dryer, and other appliances use a crazy amount of electricity. We use them sparingly, and solar offsets those costs nicely.”

Surviving 2019’s Polar Vortex

“Everything works well and we’re happy we went the Passive House route,” Brazelton says. During Minnesota’s 2019 polar vortex, which introduced temperatures that dipped to -60F in areas, furnaces across the Midwest worked overtime.

At the Brazelton's, temperatures got close to -30F. “The house didn’t struggle, but the mechanicals did a bit,” Brazelton says. “The air exchanger has a pre-heater that warms the air, and it couldn’t preheat the air enough to keep the core from freezing. For a day or two, we limped along with not the best air exchange.”

Still, the family stayed cozy. “We don’t like going to other people’s houses, especially in the winter, because we’re so accustomed to being comfortable all the time,” Brazelton says with a laugh. “At other people’s houses, we have to wear sweaters and slippers. You can feel the cold drafts that come through windows and doors. In our home, the thick walls and high level of insulation keep the temperature gradients steady in every room. Also, the house has a quiet to it. We often feel like we’re in a little bubble.”

The family is looking to extend that bubble into the garage, which houses their hybrid electric car. “We want to renovate the garage with super insulation and solar panels, with an electric charger inside, to create another livable space,” he explains. “We’re super addicted to the idea of having these bubbles we feel safe in.”