CASE STUDY | THE HOUSE AT CORNELL TECH HIGH-FLIER The House at Cornell Tech is CIBSEs 2021 Public Use Project of the Year. Andy Pearson spoke to Buro Happold to find out how an integrated approach to building services and faade design proved that highly insulated, airtight buildings can be delivered at scale I t was the CEO of Hudson Companies who threw down the gauntlet and said were going to do Passivhaus on this project, recalls Julie Janiski, a principal at Buro Happold. The project was a new, 352-unit student and faculty accommodation block for Cornell Tech, the technology campus of Cornell University, being developed in the shadow of Queensboro Bridge on Roosevelt Island, Manhattan, New York City. Hudson Companies was one of the universitys development partners, while Buro Happold was the projects MEP, structural and lighting engineer, working with Handel Architects to design what was, at the time, the worlds tallest and largest residential Passivhaus building. Another key member of the team was Steven Winter Associates; the consultant joined the design team as the project progressed, to provide specialist Passivhaus consultancy services. They were familiar with the technology and challenges of designing and building a highly insulated, airtight building envelope, Janiski says. Importantly for this pioneering project, Steven Winter Associates had an established relationship with the Passivhaus Institute in Germany. This meant it was able to have conversations about the details, and how to handle the fact that the building had a different typology from the ones more commonly certified as Passivhaus, such as the single family home. When it came to developing the pioneering Passivhaus for Cornell Tech, the design team was fortunate that the campus masterplan had conveniently placed the building on an east-west axis, so its principal elevations faced due north and south. The buildings orientation and rectangular form are ideal for minimising east and west exposure to low-angle sun and solar heat gain, says Janiski. Although, just to be sure, the team modelled the building in alternative orientations: The impact of changing orientation from facing north-south added up to 15% to its energy demand, Janiski adds. In keeping with Passivhaus principles, and in the context of a climate that spans very cold winters and very hot and humid summers, the buildings envelope is formed from a highly insulated metal-panel cladding system incorporating operable, triple-glazed windows. None of the apartments has a balcony, a feature that helps dispense with tricky airtightness and thermal-bridging details, while making it easier to wrap the insulating faade tightly around the buildings concrete frame. The architect has, in fact, taken the wrap concept and contrived the faade design to make it appear, visually, as if PROJECT TEAM Client: Cornell Tech Architect: Handel Architects M&E and lighting engineer: Buro Happold Passivhaus consultant: Steven Winter Associates Structural engineer: Buro Happold Main contractor: Monadnock Construction 18 April 2021 www.cibsejournal.com CIBSE April 21 pp18-22 House at Cornell Tech.indd 18 26/03/2021 17:26