Located in the Bronx, New York City’s northernmost borough, 425 Grand Concourse is a new mixed-use and mixed-income development that will create 277 units of affordable housing. The two-story base will house a medical facility, a supermarket, community support space, and a new student services center for CUNY Hostos Community College—each also designed by Dattner Architects. (Dattner Architects)
The green building standard known as “Passive House” is starting to see adoption in New York City, where multiple new projects are opening soon. Most significantly, the largest Passive House–certified building in the United States, 425 Grand Concourse in the Bronx, just closed its housing lottery for applicants in April.
Passive House construction is meant to conserve energy by providing an airtight insulated environment that retains heat in the colder months and keeps it out in the summer. A matrix of specialized triple-pane windows and complex energy recovery ventilation systems dramatically reduces energy consumption, saving residents money and greatly reducing the carbon footprint of a home.
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Buildings with Passive House construction standards, known as Passivhaus in the original German, have long been considered a boutique commodity due to elevated costs and norms outside traditional building codes. But as cities get more serious about fighting climate change, that may be changing.
“Passive House has been around for decades, but it’s really been embraced here in the U.S. in the last decade,” says Thomas Brown, vice president of development at Trinity Financial.
“What there is lacking in the development community is real life examples of Passive Houses being developed and testing the performance over a number of years,” says Brown, whose company forms half of 425 Grand Course’s development team with the MBD Community Housing Corporation. “The entire industry is looking at how these buildings performed and our building in particular, which is coming online now.”
The 425 Grand Concourse mixed-use structure stands 26 stories tall, with 277 units of affordable housing backed by Low Income Housing Tax Credits and local funding. It also contains a supermarket, a community health center, and a variety of educational institutions.
What really sets it apart, however, is the design promises an airtight building envelope that will allow for low emissions temperature control—and low utility bills for tenants. Like most Passive House designs, it is equipped with heat and energy recovery ventilators that whisk out stale air and brings in fresh air.
“In the affordable housing world, there’s been a real move towards Passive House,” says Mark Ginsberg of Curtis + Ginsberg Architects, who designed the Passive House project Park Avenue Green, which is also income protected. “They tend to be quieter because they are better insulated. You tend not to smell your neighbor [or suffer allergy attacks] because you have fresh air. There are a number of other advantages besides the low energy usage.”
There is an opening for Passive House standards to make an impression as policymakers and the housing industry focus on climate change. Buildings are a quiet contributor to the carbon emissions that fuel global warming. Heating and cooling the built environment is responsible for 35-to-40 percent of global energy consumption, which is often fueled by dirty sources like coal, gas, and oil. Many buildings are simply inefficient, leaking warmth in the winter months while creating oven-like conditions in the summer.
New York City is one of the greenest locales in the United States, partly because of its high residential density and low levels of car ownership. But its older building stock is extremely energy inefficient, and buildings represent a more sizeable part of its carbon footprint than the American norm. (In the country overall, transportation is the largest source of carbon emissions.)
As a result, in recent years policymakers have been attempting to address this conundrum by retooling the city’s energy code to require the largest buildings to adopt aggressive new emission standards.
“The energy code has been ramping up and getting more demanding of building performance,” says John Woelfling, a principal with Dattner Architects. “That’s been something that has pushed many projects to that threshold where it makes sense to do Passive House. The contractors are getting more accustomed to these new technologies and new systems and there is a much greater degree of comfort with putting in bids on them.”
Passive House buildings use dramatically less energy than their traditional counterparts. According to Woelfling’s predictive model, the Energy Use Intensity (EUI) for 25 Grand Concourse will be about a third of that of a typical building. Ginsberg agrees that the energy consumption of Passive House developers is generally about 50-to-70 percent less than conventional buildings.
It has taken a while for Passive House to gain popularity in America because energy is cheaper here than in Europe or Asia and so there hasn’t been the same impetus to tackle the model’s higher upfront costs. Historically, building using Passive House techniques have been more expensive than in the conventional counterparts. After all, this is specialty construction that requires heavier insulation and unique internal systems that many construction industry actors are unfamiliar with.
But as Passive House becomes a known quantity, and more players in the building industry have experience with it, Passive House is shedding some of its boutique reputation—at least in New York City.
That’s partly due to New York City as an ideal testing ground for Passive House building. These designs benefit from density of occupants and from having less exposed walls per unit than a single-family house. Multifamily housing naturally warms neighboring units, and design further enhances that already more energy efficient benefit. In an apartment or condo building with 1,000 residents, hundreds of people are using appliances and lighting at any one time-- generating heat gain that is recycled within the structure.
“In the wintertime you can heat your apartment with basically a hand dryer, as opposed to some large boiler that’s delivering steam to radiators,” says Woelfling, who led the 425 Grand Concourse project. “That ratio of exterior wall to density really is what makes multifamily and Passive House work so well together.”
By contrast, building single-family, stand-alone structures, requires higher installation costs on every one of the exterior walls. A standard American house is a six-sided box, with a lot of exposed exterior surface area that will have to be insulated. In a multi-family building each unit will only have one or two exposed exterior walls and everything else will be shared with interior spaces. There’s a lot less exterior envelope per person, which plays to Passive House’s advantages.
The specialty mechanical systems required for Passive House building will also be more expensive in a single-family setting. In multifamily construction, the costs can be amortized over more square footage.
“No matter what you do, Passive House is more complicated than standard construction so you’re going to pay a premium,” says Woelfling. “But that premium is coming down partly because there’s a lack of fear factor [as builders] get more comfortable with the system. And it’s coming down because there’s more manufacturers out there providing the equipment that needs to go into these buildings.”
Woelfling himself has become more comfortable with Passive House because of 425 Grand Concourse. That was his firm’s first project of that kind. Since then, they’ve designed three more that are now near completion. They have another series of projects on the boards now too.
“There’s a big move in New York State to electrify buildings, so it’s critical that we drive down the amount of energy that we’re using in buildings,” says Woelfling. “Passive House is a good way to do that. We have not only a housing crisis on our hands, we have a climate change crisis. Passive House just seems like the right thing to do.”
