World’s largest ‘Passive House’ office building uses Elevate insulation by Holcim delivering up to 40% improved thermal performance

  • Winthrop Center is the most energy-efficient large-scale office building ever built in a cold climate
  • Holcim contributed to the project with industry-leading roofing and insulation systems


A typical building loses up to 25% of its heat through the roof. Industry-leading Elevate roofing and insulation systems by Holcim were thus instrumental in the construction of the world’s largest Passive House-certified office building: the Winthrop Center in Boston, USA.

Holcim delivered up to 40% better thermal performance compared to competitive products with its industry-leading Elevate™ ISOGARD™ polyiso insulation, which 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.

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.

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.

Richard Baumert, Partner at Millennium Partners: “Architects and developers are increasingly looking to Passive House to curb energy use. 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. 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. 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.”

Kristin Beck, President of Commercial Roofing Systems & Lining for Holcim: "The Passive House certification of Winthrop Center highlights the superior sustainable performance and quality of our Elevate products. This 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."

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. 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.

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

Discover more about the project here.

About Holcim

Holcim is a global leader in innovative and sustainable building solutions with net sales of CHF 29.2 billion in 2022. Driven by its purpose to build progress for people and the planet, its 60,000 employees are on a mission to decarbonize building, while improving living standards for all. The company empowers its customers across all regions to build better with less, with its broad range of low-carbon and circular solutions, from ECOPact to ECOPlanet. With its innovative systems, from Elevate roofing to PRB’s insulation, Holcim makes buildings more sustainable in use, driving energy efficiency and green retrofitting. With sustainability at the core of its strategy, Holcim is becoming a net-zero company with 1.5°C targets validated by the Science Based Targets initiative (SBTi).

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This document contains forward-looking statements. Such forward-looking statements do not constitute forecasts regarding results or any other performance indicator, but rather trends or targets, as the case may be, including with respect to plans, initiatives, events, products, solutions and services, their development and potential. Although Holcim believes that the expectations reflected in such forward-looking statements are based on reasonable assumptions as at the time of publishing this document, investors are cautioned that these statements are not guarantees of future performance. Actual results may differ materially from the forward-looking statements as a result of a number of risks and uncertainties, many of which are difficult to predict and generally beyond the control of Holcim, including but not limited to the risks described in the Holcim's annual report available on its website ( and uncertainties related to the market conditions and the implementation of our plans. Accordingly, we caution you against relying on forward-looking statements. Holcim does not undertake to provide updates of these forward-looking statements.

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