A typical building loses up to 25% of its heat through the roof. To ensure an office building in Boston could buck that trend, building designers and contractors turned to Elevate roofing and insulation systems by Holcim for the construction of the world’s largest "Passive House"-certified office building: the Winthrop Center in Boston. buzz

Designed by Handel Architects in collaboration with Steven Winters & Associates and conceptualized by the internationally recognized developer Millennium Partners, the Winthrop Center is the most energy-efficient large-scale office building ever built in a cold climate. Companies SOCOTEC and WSP incorporated the Passive House design in its office portion.

Passive House principles encompass various aspects of a building, including its walls, roofs, windows, ventilation, and heat exchange systems, all working in harmony to achieve high levels of energy efficiency.

“Architects and developers are increasingly looking to Passive House to curb energy use," said Richard Baumert, partner at Millennium Partners. "Winthrop Center’s recent achievement in being certified by the Germany-based Passive House Institute as the largest Passive House office building in the world is exciting news for the development community."

The Passive House approach used at Winthrop Center is critical to significantly lower heating demand through the winter and cooling demand through the summer. A typical Class A building in Boston’s existing stock uses 2.5 times more energy than Winthrop Center’s office space. As an iconic building whose office space delivers dramatic energy savings while bringing in 30-50% more fresh air than a standard building of this type, Winthrop Center stands out as a showcase project for Passive House development and sets a high standard for future projects. 

"This demonstrates that Passive House and its energy saving principles can be applied to an office building at a size and scale that has never been achieved before," said Baumert. "Innovative building envelope solutions such as Holcim’s are integral to creating a more sustainable future through the built environment and we are proud to have partnered with them in the development of Winthrop Center."

Holcim, through its Holcim Building Envelope division, delivered up to 40% better thermal performance compared to competitive products with its Elevate™ ISOGARD™ polyiso insulation, which the company says has the highest thermal efficiency per inch available on the U.S. market. Elevate UltraPly TPO SA membrane was also installed as part of the roofing system to provide a protective, waterproof barrier from driving rain and moisture. Winthrop Center also incorporates a well-insulated façade and an air-tight exterior building envelope. 

"The Passive House certification of Winthrop Center highlights the superior sustainable performance and quality of our Elevate products," said Kristin Beck, president of Commercial Roofing Systems & Lining for Holcim. "This [Passive House] certification reinforces the effectiveness of Holcim's innovative building envelope solutions in significantly reducing energy consumption, and it also sets a standard for sustainable construction in cold climate regions."

Driving energy efficiency is one of the main ways to decarbonize cities by addressing the operational emissions of buildings. Holcim says its range of solutions, from advanced roofing systems and insulation to concrete thermal activation, are designed to make buildings around the world more sustainable in use.