Boston’s Winthrop Center is officially the world’s largest passive house office building. The 52-story mixed-use office and residential building was developed by MP Boston and designed by Handel Architects. The Passive House Institute certified the building in October 2023.
The building features an airtight envelope, triple-plane windows and an innovative cooling and heating system. The structure is enclosed in blue glass, and thanks to the aluminum-framed façade’s pleated, layered geometry, it resembles a shimmering prism.
To create the structure’s 10-foot-high windows, Sotawall, part of Apogee Enterprises, provided 10,000 aluminum frames and 1,250 vents totaling 600,000 square feet of material. The company partnered with Karas & Karas Glass Co. (Karas) on the curtainwall installation. Karas also designed, sourced and installed other façade elements, including metal panels, glass guardrails, copings and entrances, among others, to provide an entire envelope solution.
The project features triple glazed insulating glass units with glass spandrel panels to obtain an average R-value of 7.35 Btu/hr.ft².°F, according to Handel Architects. Architects add that all connections between the exterior wall and the interior structure are thermally broken to minimize heat loss through thermal bridging, and all panel joints are gasketed and sealed to prevent air leakage. Interpane was the glass fabricator.