Passive House Standard Evolves From Residential To The Skyline-Altering In Boston
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Boston developers are turning to a small-scale building standard for sky-high projects in an effort to cut energy costs and build more sustainably.
The Passive House building standard aims for projects to achieve near net-zero energy use through qualities like effective window sealing, quality insulation and heat recovery. The standard’s emphasis on airtightness to reduce energy consumption has made Passive House popular with single-family homes, as certification can be achieved more easily with fewer windows.
But developers in Greater Boston are beginning to seek Passive House certification, which originated in Germany, on projects like student housing buildings and the future fourth-tallest building in the city.
“Proposing Passive House for the commercial part of a building is a little bit funny,” Boston Planning & Development Agency Senior Architect for Sustainable Development John Dalzell said. “But you know what? A lot of things start out that way.”
The 691-foot Winthrop Center under construction in Boston could become the largest Passive House office building in the world if its developer gains certification for the 750K SF office component of the $1.35B, 1.56M SF mixed-use development.
The entire development is designed to achieve LEED Platinum certification, but the Passive House designation differs from LEED due to its focus on energy consumption once construction is complete.
A soaring glass tower isn’t the norm for Passive House, given developers and designers usually rely on fewer windows to achieve the standard’s calls for airtightness. Millennium Partners declined to comment for this story, but Dalzell said he welcomes the developer’s intent to stretch the definition of Passive House.
Others are finding a welcoming audience on college campuses.
“If you talk to the sustainability leaders at a lot of higher education institutions, they get excited when they hear what we’re doing,” SGA Director of Higher Education Jacob Higginbottom said. “They’re abandoning LEED as a metric for measuring in favor of this.”
SGA has designed the first two student residence halls in Massachusetts to seek Passive House certification, a 16K SF project at Williams College and a 45K SF residence hall at Wheaton College. Expected to open in 2019, the residence halls averaged a 2.5% construction cost premium, but are designed to achieve 50% to 80% savings in energy costs. Wheaton expects to recoup the construction premium on its residence hall after 10 to 12 years of energy savings.
Colleges and universities have driven much of the demand for Passive House as part of a greater push by students for sustainability. Net-zero energy consumption may be ideal, but it typically comes with higher construction costs. A net-zero energy residence hall in New England can cost $620/SF, while a Passive House one is just under $500/SF, Higginbottom said.
“It’s not a lot of added cost to basically get to net zero,” he said. “With those parameters, we’re seeing a lot of schools get excited by us.”
Passive House may still be in its infancy in the commercial sector, but more developers are beginning to take note. Bernstein Real Estate is developing a 24-story, 55-unit multifamily project at 211 West 29th St. in New York City’s Chelsea neighborhood. If it achieves the Passive House certification, it would become the second-tallest Passive House building in New York after a 250-foot Cornell Tech residential hall.
The 65-unit The Distillery in South Boston is the city’s largest Passive House residential project, and more multifamily buildings like it could become the new normal.
The larger the project, the lower the construction premium, according to The Passive House Institute U.S. While a single-family home with Passive House certification can cost 5% to 10% more than a conventional home, multifamily Passive House projects have between a zero to 3% construction premium depending on their size.
But not all is down and out with LEED.
Dalzell says Millennium seeking a LEED Platinum designation at Winthrop Center is still a high environmental bar to build to thanks to its emphasis on broad categories like water efficiency, sustainable sites, materials used and proximity to public transportation. The city of Boston also requires any building over 20K SF to report annual energy use, like Passive House’s energy audit in the certification phase.
The U.S. Green Building Council has also weighed in by recognizing a Passive House certification can be used to help a building attain a higher LEED standard. Rather than an either-or position, Dalzell sees a need in Boston for multiple ratings systems when it comes to energy and environmental standards.
“It’s important to keep an eye on this whole idea that an endeavor can be better and do good,” he said. “A LEED Platinum building will attract better tenants more quickly who will pay more.”