The house at 23 Park Place in Park Slope became the city's first certified passive house last year, meaning the first project in NYC to meet the German passive house standards of energy efficiency. Dwell ventures inside the house and its 20-inch-thick insulated outer wall in this month's issue. While the place was a traditional brownstone when its owners, a young couple, bought it in 2009, it was on the fixer-upper end of things, and the couple decided to get dramatic with their fixing. The windows are specially coated to keep the house warm, the appliances are all electric (the city cut the house's gas line at the owners' request), and even the brick wall that climbs the center of the house is actually just a front to a regular, airtight wall. Eventually, the owners' art will color the place up a bit.