Millennium Partners Announces Winthrop Center as Boston's First Internationally Certified Passive House Office Building

Internationally recognized developer Millennium Partners has announced that the international research institute Passive House Institute (PHI) has officially awarded Passive House certification to the office portion of the 691-foot, mixed-use tower Winthrop Center as the world's largest Passive House office building, making it the first internationally certified Passive House office building in the City of Boston. Comprising 812,000-square-feet of Global Class A office space and a luxury residential offering spanning 510,000-square-feet, Winthrop Center is designed by Handel Architects in collaboration with Steven Winters & Associates, SOCOTEC, and WSP to incorporate Passive House design in its office portion. With a well-insulated building façade, air-tight exterior envelope, and advanced energy recovery ventilation (ERV) system, the office design results in significant energy savings and superior indoor air quality and comfort.

"The Passive House concept is the only internationally recognized, performance-based energy standard in construction and may soon become the gold standard for meeting energy and carbon emissions reduction goals through the built environment," said Millennium Partners Director of Sustainable Development, Brad Mahoney. "With third-party performance designation from the Passive House Institute, Winthrop Center is at the forefront of a growing movement of energy efficient buildings providing climate change solutions."

A Bold Vision Inspiring More Widespread Adoption of Passive House Design
Conceptualized in 2017 by Millennium Partners, Winthrop Center sets a new global standard for building performance and energy conservation. Its office space was a pilot project for Passive House development, representing the first time a developer applied the Passive House approach to an office building of this size and scale. Working closely with the Passive House designer, Steven Winters & Associates, and experts at the Passive House Institute in Darmstadt, Germany was essential in bringing the vision to life.

"The Passive House offices at Winthrop Center are truly pioneering," said Senior Scientist and Joint Managing Director at Passive House Institute, Jessica Grove-Smith. "As proof of concept that Passive House can be implemented at such a large scale and this type of building, they are an important driver for much needed market change towards highly energy efficient buildings. We thank the team for the vision and commitment and congratulate Millennium Partners on achieving pilot Passive House certification."

Passive House is becoming increasingly adopted by architects and developers for large-scale commercial buildings, including office towers and other complex non-residential typologies across the globe. Adapting the Passive House standard to a high-rise is an integrative challenge in which all variables must work in tandem to achieve optimal energy balance and meet rigorous requirements geared toward minimizing heating and cooling needs and enhancing occupant comfort. These include:

• A highly insulated building façade
• An airtight building envelope
• Superior windows
• An energy recovery ventilation (ERV) system to create a comfortable interior climate

In designing Winthrop Center, Handel Architects chose a triple glazed modular curtain wall system for the office portion with thermal breaks between exterior walls and an internal structure that stops the transfer of heat energy where the panel joints are gasketed and sealed. Winthrop Center's ventilation and heating systems focus on efficiently moving air through spaces and across floors and selecting mechanical systems that can condition vast volumes with minimum energy.

The temperature-controlled indoor environment does not require significant amounts of energy for heating and cooling, in addition to heightened indoor air quality – Winthrop Center's office portion will bring in 30-50% more fresh air than a standard building of this type.

"With Winthrop Center, we wanted to think beyond the status quo, and we were ready to employ an innovative approach in order to deliver an unparalleled experience and quality of life," said Millennium Partners Founder, Christopher M. Jeffries. "With this official certification by Passive House Institute, we are introducing a new era in building design that prioritizes the environment, human comfort, and health. Through collaboration, creativity, hard work, and dedication, we've brought the most energy efficient solution for large scale buildings to the heart of Boston, and we can't wait to see more successful implementations of the Passive House method across the globe."

An Exciting Moment for Boston and Beyond
A typical Class A building in Boston's existing stock uses 150% more energy and existing LEED Platinum buildings in Boston use 60% more energy than Winthrop Center's office space.

Cities and states adopting carbon reduction strategies are increasingly interested in Passive House as a design standard for the future. Massachusetts recently implemented building codes that align with the Passive House standard, including compliance paths for Passive House as well as Passive House components in its energy code (Stretch Code).

Learn more about Winthrop Center at winthropcenter.com.

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