Handel Architects designs world’s first Passive House tower
Designing Cornell Tech’s 26-story residence hall to consume 60 to 90 percent less energy called for a robust and thoughtful building envelope, AIA partner Rockwool explains
Located on Roosevelt Island in New York City, The House at Cornell Tech is among the world’s largest passive house buildings and the first residential Passive House tower in the world, rising 26 stories and comprising 352 residences. Built to house students, staff, and faculty, the project was designed by Handel Architects to meet stringent Passive House standards that aim to achieve aggressive efficiency targets of 60 to 90 percent less energy consumption than a standard building.
In the densely packed metropolis of New York, the built environment creates 70 to 75 percent of the greenhouse gas emissions, nearly all generated by heating and cooling systems. The city is aiming to reduce Lower Manhattan’s CO2 emissions by 50 percent by 2030, with an 80 percent reduction citywide by 2050.
Better buildings are the solution. The House at Cornell Tech demonstrates the scalability and potential of Passive House principles to achieve significant carbon reductions in the multi-story urban environment. The tower’s built-in efficiency measures are anticipated to save 882 tons of CO2 per year, equal to planting 5,300 new trees.
In order to achieve its ambitious energy conservation targets, The House at Cornell Tech needed to be super insulated and tightly sealed, almost completely eliminating thermal bridging and reducing air leakage.
High-quality insulation is central to Passive construction, creating an optimal indoor climate by minimizing the need for active heating and cooling. In The House, architects integrated Rockwool stone wool products into the building’s prefabricated panelized wall system. An 11-inch thickness of Cavityrock semi-rigid insulation boards, as well as AFB and Rockboard, wrapped the building in an insulated blanket that delivers an impressive average R-value of 19 in the walls.
“The building envelope was constructed to exacting standards,” says Debra Moelis, AIA, senior associate for Handel Architects. “To achieve efficiency, new products, procedures, and innovative details were incorporated, including continuous insulation, overlapping vapor barriers, meticulous taping methods, and thermal separation of metals. Extensive, specialized training ensured that installs and sealing were carried out with precision.”
“Sustainability is not just about hitting energy usage targets; it’s about wonderful places to live and work.” - Daniel Huttenlocher, dean of Cornell Tech
In addition to helping The House meet the Passive House standard, non-combustible stone wool provides the fire safety and acoustic insulation for sound control that’s essential in multi-story residential buildings.
In the end, the architects achieved the super-tight building envelope they sought. Moelis notes that the building “heroically passed the notably difficult Passive House blower door test, with results that were four times better than required.”
Additional energy reduction and sustainability measures included an energy recovery ventilator that uses hot and cold energy from exhaust air to condition and circulate fresh air throughout the building, improving indoor air quality; glazed, triple-pane windows; and maximized natural lighting to Passive House standards. Geothermal-powered heating and cooling systems are located in a louvered ridge running up one side of the building. Residents can access energy usage data, further encouraging conservation. Rainwater collection helps to irrigate landscaped areas and native plantings around the building.
“Sustainability is not just about hitting energy usage targets; it’s about wonderful places to live and work,” says Daniel Huttenlocher, dean of Cornell Tech. To that end, The House at Cornell Tech sets the bar, creating an eco-conscious living space that’s efficient, comfortable, quiet, safe, and resilient.
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