Winthrop Square

Winthrop Square, a mixed-use high-rise in the heart of downtown Boston, will feature retail, office, and residential spaces. This iconic project incorporates an ambitious green building strategy that includes pursuing LEED© Platinum certification for the entire building, plus certification through the Passive House Institute and WELL Building Standard™ for the nineteen-story office space located above four floors of retail space. In total, the project will comprise 1.5 million SF, including 750,000 SF of office space.

The project team employed Steven Winter Associates, Inc. (SWA) and the Passive House Institute to assess the feasibility of achieving PH standards for a project of this scale. Because of the unique nature of this project, the Passive House Institute has agreed to use it as a PH Pilot Project intended to better understand and define the implications of building a high-rise office space to PH standards in a cold climate.

Office spaces face particular challenges with respect to meeting PH standards such as high internal gains from occupants, office equipment and lighting, as well as significant shading from neighboring buildings. Key high performance features designed to overcome these challenges include a unitized curtain wall façade to achieve superior thermal efficiency and air tightness, an optimized four-pipe fan coil heating and cooling system, demand control ventilation with energy recovery, and advanced lighting controls. Designing to Passive House standards will drastically reduce the project’s greenhouse gas (GHG) emissions, making the building well-positioned to help the City of Boston meet its stringent GHG emissions reductions targets. If certified, the project is slated to be the largest Passive House office space in the world.

SWA performed a range of Passive House feasibility consulting services including PHPP modeling with variant analysis, 3D thermal bridge modeling, and direct coordination with the certifying body on specific certification requirements for this very unique project. Thermal modeling in Heat3 provided the project team with a detailed performance-assessment of a custom unitized curtain wall design. This assessment allowed the project team to determine if the available curtain wall systems that meet the required structural and constructability requirements for Winthrop Square will achieve the necessary level of thermal performance for Passive House certification. Currently, SWA is working collaboratively with the Passive House Institute and the development team to move the project forward towards PH certification.

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