Rendering of Knickerbocker Commons.

Rendering of Knickerbocker Commons.

The last thing you’d expect from affordable housing is energy efficiency and forward-thinking design, but two new buildings in Brooklyn are aiming to reduce the cost (monetary and environmental) of things like heat and gas.

Knickerbocker Commons, in Bushwick, and a yet-to-be-named building on the Ridgewood border will employ an eco-friendly design that has become increasingly common in Europe but is relatively untried here.

Over 20,000 “passive houses” — including schools, hospitals and churches — have sprung up across Europe in the past decade. The airtight buildings maximize energy conservation via heavy insulation, strategically placed windows, and high-functioning ventilation systems. They’re heated partly through solar energy from outside, and partly through energy captured from inhabitants by a “heat exchanger” that recycles outgoing air back into an incoming ventilator.

According to Chris Benedict, the Manhattan-based architect who designed the two buildings bound for Brooklyn, the use of high-end ventilation systems is less expensive than traditional fossil-fuel-based heating systems and can save up to 90% of the energy consumed by most large-scale apartment buildings.

Rendering of 424 Melrose.

Rendering of 424 Melrose.

Knickerbocker Commons — a six-story, 24-unit complex for individuals and families earning 30 to 60 percent of the area’s median income — will offer 4,957 square feet of community facility space, a senior citizen center, additional recreation space, and seven parking spaces, according to the City Planning Commission.

It’ll also be equipped with a heat-exchange ventilation system. And the building’s windows will have coverings that shade the glass in the summer but let light inside during the winter, when the sun is lower in the sky.

According to Benedict, all of this adds up. “The heat from natural light and the people from most day-to-day activities is enough to keep the houses warm and livable,” she says.

In the event of extreme cold, heat can be provided from a small external source, such as a coil, Benedict said. There will also be boilers on the roof as well as thermostats in apartments.

The location at 424 Melrose St. encompass 30,000 sq. feet and is currently about 70% complete, according to Benedict.

Although the internal structures of passive houses are complex, they aren’t that expensive to build. “My partner Henry Gifford and I have a history of making very energy-efficient buildings and we bring them in for the same price as typical construction,” Benedict said.

The petition to start construction on Knickerbocker Commons was first filed by the department of Housing Preservation and Development in November of 2009. After slogging through reviews with the Department of City Planning and a series of Community Board 4 hearings, construction was finally green-lit in 2010. The buildings are being financed in part by the Bushwick Ridgewood Senior Citizens Council and also the New York State Housing Trust Program, which provides funds for low-income housing projects.

Benedict believes passive houses are steadily gaining popularity in the states (Brooklyn has seen an influx in very recent months), and says she has “a few coals on the fire” when it comes to building more of them in the borough and beyond.