A Trend-Setting Building With a Small Carbon Footprint Grows in Brooklyn
Friday, March 11, 2011
A contemporary, gray apartment house on Grand Street in Brooklyn is one of the most energy-efficient buildings in the city -- and may be a symbol of the future of New York architecture. The recently completed building in Williamsburg is the first of its kind in New York City.
Carbon emissions from buildings account for 75 percent of the city's total carbon emissions, but so-called Passive Houses make use of a new architectural trend that relies on thick insulation, air-tightness and warmth from the sun to significantly reduce the carbon footprint of buildings, cutting energy usage by 90 percent.
Architect Sam Bargetz and partner Werner Morath of LoadingDock 5, the firm behind the Williamsburg building, said ventilation is at the heart of how a Passive House functions. While a normal building in New York City lets in air through nooks and crannies, a Passive House is super air-tight, so air can't escape. This is called an "envelope" and is the difference between a house wearing a loose-knit wool sweater and a Goretex jacket.
LoadingDock5 are members of the newly founded group New York Passive House, the local chapter of the National Passive House Alliance, which started in November 2010. The Alliance trains architects, contractors and developers how to plan a Passive House using the software and how to ensure that the construction meets up to standard once it is built.
The high-tech, Passive House system was developed in Germany about 20 years ago. The ventilation system doesn’t just ensure that warm air from the top of the building is circulating to the cooler parts. It also exchanges the hot and stale air inside for cool, fresh air outside -- without losing all the energy in the process.
"This is a heat-transfer system," said Morath, touring the Grant Street building. "The air channels pass by one another, so the heat from the outgoing air passes to the incoming air -- so you don't have to heat so much."
Airtightness isn't enough, however. Passive Houses need to retain heat as well. The stucco façade of the building conceals a super-thick, super-efficient seven-inch layer of foam insulation. In order to figure out how much insulation was needed, Bargetz and Morath used special software that starts with climate data from New York City -- the temperature highs and lows and humidity levels -- and lets them adjust the insulation and size of the heating unit until they hit the magic mark.
"We compare places in Austria where we are from and with our modeling software can switch the climate data," Bargetz said. "If this house was in Europe, it would need double the amount of insulation to meet Passive House standards."
Recently, construction worker Frank Dagasino, who has been working in the apartment all winter, was only wearing a buttoned down work shirt as he plastered over the last remaining holes in the walls.
"Last week, it was nine degrees outside in the morning," Dagasino said. "But it didn’t go below 50 in here, and there is just temporary heat on -- just space heaters and no heat, you know. It's a good design."
The city location is also ideal for a Passive House apartment building because of the bright sunlight that streams in to the building through the solid glass, 20-foot high south-facing wall of what would soon be an open-plan living room in the upstairs duplex apartment. These windows, like the rest in the apartment, are as thick as the walls, super-efficient and triple-paned. The position of the house and its windows are part of the computer calculation for total energy usage.
"One of the main functions of a passive house is that it heats itself by the solar gain," Bargetz said. On average, the sun shines on New York City 234 days of the year.
But the windows are also the reason that the apartment building cost about 5 percent more to build than a normal structure of its size and style: they were imported from Austria. That's not much compared to the early days of Passive House building, where construction markup was more like 20 percent.
A few years back, the architects would have needed to import nearly all of the materials to build in the Passive House style. But as interest has grown along with rising energy costs, so has the market for energy efficient building products like insulation and windows. The architects said the savings on the other side will make up for it.
"We expect to pay 10 percent," said Morath, who will live with his partner in the top duplex. "That means our whole heating bill should be a few hundred dollars –--not per month, but the whole season."
The Urban Green Council, a group that’s worked with the Bloomberg administration on green building legislation, calls the construction "a lighthouse" for the future, but says that the market is not quite there yet. They’re pushing for “Energy Star” standard instead -- given to buildings that reduce energy usage by 25 to 30 percent.
Across the country, there are dozens of Passive House buildings under construction, but after coming late in the game, New York seems to be taking the lead.
"Brooklyn has the highest number of projects in the country based on the number of architects and different projects," architect Ken Levinson said at a recent meet-up of about 25 architects in Williamsburg.