If I say the words “passive house,” you might picture a storybook cottage surrounded by lush meadows and gently rolling hills, completely off the grid somewhere in the German countryside. At least that’s what I think of (maybe because that’s where the structures that use insulation, carefully placed windows, and a few other architectural tricks to heat and cool themselves without much energy originated). But Ruth Mandl and Bobby Johnston, the husband-and-wife architects behind CO Adaptive, are here to prove that a passive house with zero energy output can be anywhere and look like anything—even a 1889 brownstone in Bed-Stuy, Brooklyn.
The couple found the townhouse in 2016 after six months of looking for a place to call their own and many drives through the streets of Brooklyn. “We could tell that the bones of the house were already great, and we loved the proportions of most rooms,” says Ruth. “It was totally livable,” she adds—in fact, they moved in and lived there for five months before renovating—“but there were nails sticking out of the subfloors, and the bathrooms and kitchens were last updated in the ’80s.”
But Ruth and Bobby’s vision went well beyond fixing a few nails. They wanted to brighten and update the whole place, carve out a spacious kitchen in the back of the house, and divvy up the two upstairs bedrooms to create three for their growing family. They also wanted to create a separate apartment on the garden level, with an eye to creating an income property. But by far the biggest undertaking of all was their plan to retrofit the entire structure into an energy-efficient certified passive house, all while preserving original details and century-old charm. The result is an airy, serene house that just happens to use zero (yes, zero) energy.
Before they took the interiors down to the bricks, the couple and their contractor, LB General Contracting Corp., salvaged what they could, including the intricate millwork, which they set aside and saved to reinstall later. Then they got to work. “A passive house involves a significant amount of insulation—about double to triple code, minimum—on both exposed facades, at the roof, and underneath the cellar slab,” Ruth explains. “In addition, there’s a smart membrane that wraps around the entire building. This membrane is moisture-open but airtight, and is probably the most important feature in achieving the 80 to 90 percent reduction in heating and cooling loads that passive houses exhibit.” With the house down to the studs, the team did both, and added triple-glazed windows, special exterior blinds that stop sunlight from heating up the house on hot days, and solar panels on the roof.
Ruth first fell for passive houses in her native Austria, when her father inherited her grandparents’ house in Vienna and retrofitted it into a passive house. “I ended up interning with the Viennese architects who renovated the house and learned a lot about the methodology, both through working on the design and later experiencing the quality of living in this house firsthand,” she says. “Since these buildings are so airtight, there’s an ERV system that filters and distributes outside air throughout the house. It heat-exchanges the air so that little energy is lost in this process. The result is that, in addition to the immense savings in energy, passive houses are very quiet, and the air inside them is always fresh.”
With the bones of the couple’s brownstone up to precise passive-house standards (and the gas line capped, since the house no longer needs a furnace), the team set about working on the interiors.
The space under the stairs is cleverly fitted with hidden storage. “The tallest section is our pantry,” Ruth says. “We also have one compartment for cleaning items and the vacuum cleaner, one for winter and fall coats, and the lower ones towards the vestibule are used for shoes and smaller storage.”
Upstairs, the couple divided a large bedroom into two smaller ones and redefined closet space to create an extra bathroom. Now, “the duplex has three bedrooms and a slightly unorthodox division of bathrooms,” Ruth says. On the second floor, there’s one powder room and two “wet rooms,” she explains: “one with a shower, a large tub, and a double sink, and the other with a shower and a sink. Dividing the toilets from the ‘clean bathroom functions’ in this way is a very Austrian or Viennese thing to do, but not very standard here in the States,” she adds.
So what’s the verdict, a year and a half after finishing work and moving in? “Life in the house is fantastic,” Ruth says. “We had a stark contrast when moving in, as we rented an older New York tenement building while our house was undergoing renovations. Some of the things that really stand out are that the heat is very even, day and night. I don’t have to worry about the radiators randomly coming on and off outside of my control, and either making my daughter’s room way too hot while she was asleep or becoming freezing cold quite quickly. The quiet is a fantastic aspect as well: There can be a block party going on outside, and she can peacefully sleep in her room without hearing more than the distant sounds of it.”
Best of all: You know that electricity bill you get every month? “Our energy bills are actually zero,” Ruth says. “Because we also have solar panels on our roof, over the year we put more energy into the grid than we take out—even factoring in that we charge our electric car.”
Here’s hoping Ruth and Bobby give more beautiful historic properties the passive house treatment. In the meantime, if you want to see what it’s like to sleep in a passive house, you can rent their garden-level unit, available on Airbnb.
Originally Appeared on Architectural Digest