Columbia Condominiums, Brooklyn, NY
The reasons for the quick sale of the 13 condominiums at 255 Columbia aren’t hard to find. While a great location is always an inducement, the built-in Passive House benefits made these two-, three-, and four-bedroom units irresistible. It’s rare that a residence includes a constant supply of filtered fresh air, thanks to individual ERVs, barely perceptible street noise, and a pittance of a utility bill for heating and cooling. And, then there are the outdoor spaces—a 2,000 ft2 common garden and private outdoor spaces for each unit in this 7-story building—generous amenities in a city that defines urbanism.
The front 10-ft by 18-ft terraces, which face south-southwest, serve as green retreats and provide an important Passive House function: each shades the unit below. They were also a classic Passive House challenge, requiring the use of thermally broken connectors to stop the thermal bridging and potential heat loss at the points where the terraces are joined to the main building structure.
The site’s poor soil quality added to this development’s construction challenges. In order to hit minimum soil-bearing capacity, ground compaction was needed. To lessen the building’s weight, the structure started with a medium-gauge, steel framing system that was manufactured off site. The wall panels were sheathed, air sealed, and water proofed, before being trucked to the site. Exterior walls that abut neighboring buildings are insulated with 2 inches of XPS, and a 6-inch exterior insulation and finishing system (EIFS) was applied to those walls that are exposed to the elements.
A reclaimed wood canopy creates a warm welcome to the small lobby, dominated by a green living wall—a tribute to the building’s Passive House design. Each apartment features large triple-pane windows, individually controlled heating and cooling supplied by mini-split heat pumps, and many designer touches. Several residences have dramatic views of Manhattan and the New York Harbor.
(text by Mary James from Low Carbon Productions)

Passive House Metrics
Heating energy kWh/ft²/yr 3.17 kBtu/ft²/yr
Cooling energy kWh/ft²/yr 2.86 kBtu/ft²/yr
Treated floor area 22,755 ft²
Air Leakage ACH50

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