Winthrop Center | 2018-2023

Location: Boston, Massachusetts, USA
Architect: Handel Architects
Lead Architect: Blake Middleton
Construction Manager: Suffolk Construction
Interior Designer: Handel Architects
Sustainability: Steven Winter Associates
MEP: WSP
Structural: DeSimone Consulting Engineering
Envelope: SOCOTEC
Client: Millennium Partners
General Contractor: Suffolk Construction
Photographers: Bruce Martin and Steelblue

Located in Boston's Financial District, Winthrop Center is the largest Passive House commercial building in the world. It includes over 1.8M sq. ft. of residential, office, and retail space. The building is a new beacon on the Boston skyline, designed to give definition and vitality to this part of the city. Winthrop Center seeks to enhance and revamp the existing Winthrop Square, creating new open space to serve Boston, and linking together several other adjacent outdoor spaces.

A grand new public space entitled the Connector anchors the building and traverses the site between Federal and Devonshire streets. This space is a year-round gathering place that includes activities such as art shows and farmers’ markets, as well as more permanent retail establishments and restaurants. Winthrop Center has been designed to use 65% less energy than the average Boston office building, and uses three separate sustainability standards: Passive House, WELL Gold, and LEED Gold.

The entire building is LEED Gold, while the office program is also Passive House and WELL Gold Certified. This is achieved through a high-performance façade, low-energy mechanical system design, and an operational approach focused on improving tenant health. To meet the high bar for energy performance, particularly at the office program, the exterior envelope needed to meet rigorous quality control during installation. The curtainwall design employs a robust, triple glazed insulated glass window unit coupled with glass spandrel panels to obtain an average R-value of 7.35 Btu/hr.ft².°F.

To reduce energy loss, 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. Space cooling is provided by state-of-the-art variable-speed magnetic levitation chillers, which are highly efficient when not operating at peak load. This provides big energy savings, since the high-performance façade limits the amount of time the interior spaces require peak cooling.

Fresh, filtered, outdoor air is delivered to all spaces by a Dedicated Outdoor Air System (DOAS) outfitted with energy recovery and variable speed-fans, whose enthalpy wheels recover more than 70% of the thermal energy before air is exhausted. Hot water is provided by condensing boilers that are nearly 20% more efficient than traditional gas boilers. The office portion of the building is designed to use 50% less water than the baseline condition through low-flow plumbing fixtures and storm water recycling.