By Alison Gregor / Source: nytimes

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It was less than a decade ago that a building design philosophy from Germany called “passive house” jumped the Atlantic Ocean and quietly took root in Brooklyn.

Now, with a few dozen homes and small projects built or retrofitted to this still exotic standard, passive buildings appear poised to enter New York City’s housing market in a much bigger way. Large projects delivering hundreds of new passive units to market are in the works, and city officials are watching closely.

Passive buildings maintain a comfortable interior climate without active heating and cooling systems — that means no more radiators or air-conditioning units for people who live in environments more temperate than New York’s. This is done using, among other things, an airtight building envelope and a system that exchanges interior and exterior air, usuallly an energy recovery ventilator. In New York, small heating and cooling systems are generally included in passive homes.

A house built to passive standards uses less than a quarter of the energy of a traditionally powered home, according to the Passivhaus Institut, which developed the standard in Germany. Besides lower energy bills, benefits include quiet interiors because of thick, insulated walls, along with fresher, cleaner air, thanks to the filters in energy recovery ventilators. Builders and residents of passive houses say the filters can help eliminate allergies and asthmatic symptoms.

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Stephen Lynch, an architect, with his wife, Hannah, and children Vera and Silas, in the Brooklyn townhouse he retrofitted using passive-house principles. Pablo Enriquez for The New York Times
With a small group of developers, builders and architects convinced that passive standards can now be achieved at little or no extra cost, proponents hope to see a revolution in how homes and other structures are built in the city.

“Building to passive-house standards just makes a lot of sense,” said Stephen Lynch, an architect and principal of Caliper Studio, who retrofitted his townhouse in South Slope, Brooklyn, using passive house principles two years ago. There are some cost hurdles and a learning curve, but those challenges can be overcome, he said, “and then you realize how amazing it is that we don’t already build to these standards.”

Officials working to implement Mayor Bill de Blasio’s sweeping green-building initiative, which has a target of an 80 percent reduction in greenhouse gas emissions by 2050, are studying passive-house standards as they overhaul performance standards for new construction.

Worldwide, buildings are responsible for about 40 percent of carbon emissions, but in New York City, it’s closer to 71 percent. The Mayor’s Carbon Challenge Progress Report of 2013 found that residential buildings account for 37 percent of the city’s emissions.

“We’ll be looking to high-performance innovations, such as passive-house, carbon-neutral or zero net energy strategies, to inform the city’s standards to reduce energy use in both new construction and our older building stock,” said Amy Spitalnick, a spokeswoman for the mayor.

Buildings constructed to passive standards aren’t widespread enough for consumers to inadvertently bump into them — they still have to be sought out. Among the small adherent developments is 255 Columbia Street, a 13-unit building in Brooklyn marketed in late 2013. And dozens of townhouses in Brooklyn and Manhattan are undergoing passive retrofits.

The cost of creating a passive house has been much debated. A few years ago, the Passivhaus Institut put the additional cost in the United States at somewhere around 6 percent. But proponents say costs have come down as prices for materials dropped and contractors have become more familiar with passive-building methods. Triple-pane windows and added insulation may add costs upfront, but these expenses are offset by the smaller boilers and smaller heating and air-conditioning systems passive houses require.

Kurt Roeloffs renovated his townhouse on West 88th Street in Manhattan using passive systems that he says did not add any extra costs to the renovation. Since moving in this past November, he’s been nothing but satisfied living in his home, where the temperature is a constant 72 degrees, and he can walk around barefoot in a T-shirt in total comfort in the winter.

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The Lynch family’s kitchen. Pablo Enriquez for The New York Times
“We were so impressed with how quiet it is, and how comfortable it is,” he said. “The air just smells fresh and sweet, even after we cook, because the filters get rid of it so quickly.”

His house uses an energy recovery ventilator, which pushes out stale air while drawing in fresh air, exchanging heat in the process. During the winter, heat from the exhausted air is transferred to the incoming cold air; and in summer, heat and humidity are drawn out of incoming air and transferred to the outgoing stale air.

David and Aliana Spungen have two-story windows in the kitchen of their Brooklyn Heights townhouse, recently retrofitted to passive house standards.

“I remember thinking we’ll probably feel a lot of cold coming off those windows,” Ms. Spungen said. “But even with this brutal winter, we just don’t.”

Mr. Lynch, the architect, said it now cost him about $323 a year to heat his 3,140-square-foot house with a gas boiler. “I’m really satisfied and interested in how to make this method of building more commonly used,” he said.

Heating an ordinary townhouse of similar size with gas would cost about $2,500 a year, said Anthony DelleCave, a salesman at Citi Habitats who manages townhouses in Brooklyn and Manhattan.

Another passive apartment house in New York is an eight-unit building at 210 Pacific Street in Cobble Hill, Brooklyn, designed and developed by NAVA Companies. The building, which has half-floor and full-floor units of three and four bedrooms, has many green elements, such as solar thermal hot water systems and induction cooktops.

However, also of interest to potential buyers is that the building’s passive design should cut their energy consumption by 75 percent, according to marketers at Brown Harris Stevens, using data provided by the Passivhaus Institut. They note, however, that the actual energy savings depends on the individual apartment owner, with those who opt for 65-degree rooms during the summer or an 80-degree home during the winter saving less than those who aim for more moderate interior temperatures. Half-floor units start at $2.45 million and full-floor units start at $4.9 million.

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