Although passive house products such as imported high-performance triple-paned windows still sell for a slight premium, they significantly pay off in the long run by eliminating thermal bridges, creating airtightness, and increasing comfort for inhabitants. “Consequently, you don’t need to have perimeter radiator heating or air conditioning — you can get rid of all of those mechanical systems and pull them back to the core of the building,” Levenson says. “Because of the optimization, which should be driving energy loads down by 85 or 90%, there typically is 75% reduction in size of mechanical systems needed for heating and cooling.”
One architect practicing in New York has even found a way to incorporate passive house technology into affordable housing. Chris Benedict, principal of Architecture and Energy Limited, has built two 24-unit affordable housing developments in the Bushwick neighborhood of Brooklyn that are on the way to achieving passive house certification. Currently, she is getting ready to break ground on a market-rate 40-unit apartment house, which will be the first passive house residential building in Manhattan.
According to Benedict, who has been designing energy-efficient buildings in New York City since 1996, the growing popularity of the passive house standard has made it easier to sell her specialized skills to clients. “I was in the energy-efficiency world prior to the arrival of the passive house standard in the US,” she says. “Before, if I was going to talk with people about energy-efficient buildings, I would have to talk about tons of different things. Now all I have to do is say passive house.”
In addition to being responsible for several of the largest passive house developments built to date in this country, Benedict has also played a role in getting zoning and building codes changed to make these types of buildings more cost effective for developers. For example, in New York City, prior to zoning code changes, developers interested in more energy-efficient buildings actually stood to lose the amount of allowable floor area because of the extra wall thickness that passive house requires. “In new construction it was a tough nut to crack for developers,” Benedict says. “What is nicer for developers than a glass building where the wall thickness is 2 inches? That is a lot more developable floor area because the wall thickness was counted as part of the floor area of the building.”
However, three years ago, Benedict successfully lobbied the New York City Planning Commission to allow floor area bonuses for extra insulation on both preexisting and new construction. As a result, on new construction in New York City, any building that has a wall thickness of more than 8in does not count as floor area so long as the wall assembly has a higher R-value than the current building code’s R-value requirement.
The change in the zoning code is already paying off for Benedict’s clients. On the market-rate passive house Manhattan apartment building that Benedict designed, she has been able to recover about 800ft2 of floor area for the developer in exchange for providing walls that exceed the New York City Building Code’s insulation requirements. This amount “was the cumulative extra thickness of insulation that didn’t have to count as floor area,” she said.
Currently, there is a debate within the US building science community as to which passive house standard to adopt. Most of the existing passive house buildings in the United States have received their accreditation from the original Passive House Institute (PHI), founded in Germany. And in order to receive PHI certification, an inspection is required by one of the institute’s accredited inspectors. However, there is also a Belgian Passive House standard, as well as a Swedish Passive House standard. In 2007, several architects split from the German passive house standard and founded their own organization called Passive House Institute US (PHIUS).
One of the big bones of contention between the German-based PHI and PHIUS is a difference of opinion over what a building’s maximum energy loads should be in order to qualify for certification. Benedict says that the PHI standards are impractical for very hot or very cold climates in the US that are unlike that of Germany, and that it would be more practical to have limits on peak energy loads rather than on yearly energy use. “One of the reasons we haven’t had the huge launch that could have happened in this country is because of the rift and the fighting that has been going on,” she says. “That has confused the marketplace a bit, and it also has confused practitioners who hear one thing and then another, so they don’t know which way to turn.”
It will doubtless take time for the competition between the different passive house institutes in this country to play out, and perhaps there is room for several different types of standards. Meanwhile, it has become much easier to build these types of buildings as a result of passive house technology becoming significantly more affordable and regulatory barriers being removed in places like New York City. With US cities tightening their energy codes, it seems clear that the building industry in this country will soon need to know a great deal more about passive house technology than it does now.
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