The Passivhaus, or Passive House standard is tough to meet. (See more on the standard here in TreeHugger) But many believe that the results in energy savings and comfort are worth the trouble and cost. At 270,000 square feet and 26 stories, a new residence being built on New York City's Roosevelt Island for Cornell Tech's new campus is breaking all the records for Passive House height and size. Architect Blake Middleton of Handel Architects tells Adele Peters at Fast Company: "It's been an exploratory process for us, partly because nobody has done anything of this scale."
The Passive House standard has strict limits on energy consumption; in some ways, that is easier to do in a multifamily building because apartments usually only have one wall to the exterior. Here, the exterior walls are fourteen inches thick prefab panels with triple glazed windows. Blake Middleton tells the New York Times:
“The reason we chose a panelized system was both for speed of construction,” he said, “and also to cut down on the number of joints that would be required to be all very carefully sealed by the builder on a floor-by-floor basis.”
Scott Gibson provides more detailed technical information on Green Building Advisor:
Arianna Sacks Rosenberg, senior project manager with the developer, the Hudson Companies Inc., said by email the wall sections are 14 inches thick at their deepest and insulated with 11 inches of mineral wool. Some areas of the wall are thinner. R-values range from 18 to 30, Rosenberg said, with an average R-value for the assembly 20.
The triple-glazed windows, made by Schuco, have a U-factor of 0.156 (calculated by the European method). Windows will be shipped directly to Eastern Exterior Wall Systems, which is manufacturing the wall components, so they can be incorporated during assembly.
The fun will begin when it gets tested for air changes per hour. This is also an easier target for big buildings, since it is measured as a function of the volume of the building and a multi-family building has a lot more volume in relation to its exterior surface area, but things can get weird when buildings get tall and the wind starts acting on them. Buildings flex and low pressure on the downwind side can suck air out through the smallest leak, so those prefab wall panels have to be installed perfectly and sealed carefully. That will be a real challenge. But it is worth it; as Ken Levenson of the NY Passive House org notes, it “is a clear signal that in today’s era of climate change, it’s not enough to simply build tallest. To lead the market, your tall building will need to be a passive house.”
On his own website, Ken Levenson proudly calls it the BOOM! heard round the low-energy/high-performance world, channeling Lisa Minelli and noting that "If Passive House can make it in New York, it can make it anywhere."