New York City wants to cap fossil fuel consumption on multifamily buildings at 55 kbtu/sf by 2030, a goal that some argue is far too aggressive.
The emphatic dismissal of that concern is Frost Street Apartments, a 47-unit, 45,000-square-foot multifamily property in Brooklyn.
The deeply affordable housing property is rated at 35.3 kbtu/sf, about 36% below the 2030 cap. “The energy efficiency is at passive house level,” reports architect Mark Ginsberg, FAIA, principal of Curtis + Ginsberg Architects, the design team behind the seven-story, $13.3 million project.
$213 per Square Foot versus $375 per Square Foot
At a construction cost* of $213 per square foot (versus an average multifamily construction cost of $375 per square foot), achieving passive house efficiency is the happy result of some very smart early decisions. Notable among them: an envelope of insulating concrete forms (ICF).
The cast-in-place concrete wall system is well-documented for its affordability and resilience to hurricanes and other extreme weather events. What may be less understood is the wall system’s thermal performance characteristics.
“A large part of the energy savings is due to the ICF. ICF provides a really good envelope,” says the award-winning architect. “Basically it gives you passive house performance in very few steps.”
Engineered Simplicity
Emphasize “a few steps.” The engineered simplicity of the all-in-one assembly reduces the number of trades required. Lightweight sandwiched foam bricks are stacked to create a casting form. The foam layers remain in place as interior and exterior insulation. Besides insulation, you can also check off structure, vapor barrier, and air barrier off the to-do list. Metal studs on the inside wall are perfect for drywall hanging, and studs on the outside for brick placement, if specified. “Once you add a temporary roof, you basically have a watertight building,” says Ginsberg. “It’s a really well-insulated façade.”
The Frost Street Apartments project is Curtis + Ginsberg’s ninth ICF structure. “It’s a great product. There are so many design options with ICF. You can use brick, stucco, fiber cement, metal panels, you name it. You’d never know it’s an ICF building. ICF allows you to do things that a block-bearing wall doesn’t allow,” says Ginsberg.
Affordable Housing Reimagined
Frost Street Apartments dramatically illustrates the extra design dimension. The staggered use of setbacks and cantilevered window framing across the front profile complements, if not surpasses, the look of the market-rate apartment complex next door. This is affordable housing as it should be—bright, clean, stylish, and environmentally responsible. Full occupancy was never in doubt. “There were at least 80,000 qualified applicants for the 47 units,” explains Ginsberg, describing the lottery selection process.
Form Fits Function
For Ginsberg and his design team, the opportunity to support the affordable housing industry is always gratifying. Assisting low-income residents with clean, safe housing is imperative for the city. So much so that the mayor has pledged to build 200,000 affordable housing units over the next 10 years. “New York City is building more affordable housing than the entire state of California. Yet, it’s not enough,” says Ginsberg.
The good news is that ICF points a way forward in terms of resilience, energy savings, design flexibility, and project economy that few building methods can match.
To learn more about ICF in your next development, visit BuildWithStrength.com.
*Frost Street Apartments is an inclusionary property; the land cost is donated by the neighboring market-rate development
