East Village Passive
Affordable Multifamily to Passive House Standard
New York, NY
NYC HPD selected us to develop this project under the City’s Neighborhood Construction Program. Asian Americans for Equality is the sponsor and Leroy Street Studio is the architect. The project includes two buildings in the East Village, one with 44 residential units, the other 10, both with ground floor commercial and community facility. The larger will be built to Passive House standard and the smaller to Enterprise Green Communities certification.
The larger building is a shoe-in for Passive House. It is bulky enough to have a very low surface area:floor area ratio, and has near-perfect solar orientation and exposure. Preliminary modeling shows the project easily meeting PH certification with code-compliant insulation levels in all components.
This says something about building energy code: it is catching up with best practice. In my opinion, code R-values are very stringent, with the exception of windows. And it's great news that code is finally catching up with air tightness, even requiring blower door testing for residential buildings and some commercial buildings. So how will this Passive House differ from ordinary construction?
First, the NYC code limit of 0.4 cfm75/ssf is much less stringent than Passive House, which for this building would be 1/4 (PHI) or 1/6 (PHIUS) as much.
Second, to meet PH energy targets, balanced mechanical ventilation with heat recovery will be required. Code does not require this, although I think it should. As our buildings get tighter, even while we give people plenty of opening windows, research seems to show that air quality still gets worse. For health reasons, we should be putting balanced mechanical ventilation in all new construction, and at that point, we might as well add heat recovery. People older and wiser than me agree.
Third, the Passive House method ensures that design R-values are realized in the final construction. This is very different from NYC code, primarily because code does not yet govern thermal bridging, for example at slab edges, balconies, parapets, cladding supports, and window installation. We worked on this in the last round of city code advising and are hoping to drive it home in the next round.
The smaller building, more exposed to the cold and shaded from the winter sun, will pose a serious challenge to Passive House, but that won't stop us from making an exceptionally healthy, comfortable, economical, sustainable building.