Tallest Passive House Building in the World

The Cornell Tech dormitory will be the tallest Passive House building in the World. Artwork by Handel Architects.

By George Harvey

Cornell Tech, part of Cornell University, is a new applied-sciences campus in New York City, on Roosevelt Island. The first classes started in 2013 at temporary quarters in a building Google owns on EighthAvenue. Construction began on Roosevelt Island late the same year.

The campus will be very environmentally friendly. A lot of green space is designed in, and the buildings are all being designed and constructed to the highest standards. Consideration for carbon emissions has been particularly painstaking.

The university is working with the Hudson Companies and the Related Companies to develop the campus’ dormitory, which is 250 feet tall and will house 520 people, including students, faculty, and staff. It is a noteworthy structure for many reasons, two of which are of particular interest. One is that it will be the first high-rise residential building ever to meet Passive House standards. The other is that it will be the tallest Passive House building in the world. The building’s design is being undertaken by Handel Architects.

One of the toughest problems in building to the Passive House standard is dealing with air infiltration and ventilation. Every tiny crack has to be sealed to prevent untreated cold air from entering the building and wasting heat. At the same time, ventilation has to be maintained for the health of the occupants, and preservation of the contents of the building. The design team specified a special heat-retaining ventilation system that was not covered yet in the building codes of New York City, so special permission had to be obtained for it to be installed.

Standard construction for the Passive House standard requires a doubled outer wall for insulation. To meet that standard, the amount of glass was significantly reduced. Fully glazed walls might have been nice because of the rather grand views the building would have, but they were not included because of costs. The designers opted for somewhat smaller windows instead.

The Passive House standard brings a building to the point that ordinary human activities provide enough heat for comfort, nearly all the time. The occupants’ body heat, cooking, and electrical equipment such as computers, and solar gain are all heat sources. A Passive House building should have backup heat, but it should not be needed much at all.

In the end, the design of the building makes it possible to reduce energy consumption by 70%. Remarkably, this is accomplished by a 5% increase in the cost of construction. Since the cost is $115 million, this is not an insignificant figure. Nevertheless, with such a large reduction in heat consumption, the cost increase should be recovered rather quickly, and will be repaid many times over in the expected lifetime of the building. The elimination of 882 tons of carbon dioxide each year is just one more benefit.

Because it is so visible, the Cornell Tech dormitory is expected to influence building design elsewhere. It will be an object of study for current architects and builders. It will also be an object of inspiration for the students who live there.