Boston soon to be home to one of the largest 'passive' design buildings

Winthrop Center office building in downtown Boston is one of the largest buildings in the world to use passive house design. (Credit: MP Boston)
Winthrop Center office building in downtown Boston is one of the largest buildings in the world to use passive house design. (MP Boston)

An office building in downtown Boston is expected to become one of the largest buildings with a "passive" design after it cleared a certification milestone earlier this week. The concept involves a combination of strategies that drastically reduce energy use as much as 70%. The 812,000-square-feet Winthrop Center space passed several key tests Tuesday; offices are expected to operate this summer.

The passive house design concept starts with the facade, which has to be well-insulated and air-tight, said Brad Mahoney, director of sustainable development at Millennium Partners Boston, which owns the building.

“You're adding an extra layer of glass, you're adding more insulation. So if I were to be sitting by the exterior right now, I would not be cold. It wouldn't be noisy,” he said.

Because of the building’s air-tight design, it also has a ventilation system that brings in fresh air. The developer said Winthrop Center provides 30% to 50% more fresh air than comparable buildings.

And the passive house design greatly reduces the need to heat and cool the building — up to 10 times less compared to typical buildings. The system is more efficient, but what drives the lower demand is the building's insulation and air-tightness.

In Boston, buildings are responsible for nearly 70% of greenhouse gas emissions, so reducing their energy consumption could make a significant impact. Typical comparable office buildings use 150% more energy than Winthrop Center, while LEED certified buildings use about 60% more, according to the developer.

On Tuesday the building passed a series of tests to become certified by the Passive House Institute in Germany. It was also awarded The Passive House Trailblazer award.

“When we started this back in 2017, I think there were probably a handful of passive U.S.-certified buildings here in Massachusetts. And they were small and they were residential,” Mahoney said.

Using passive house design costs about 2% to 3% more than constructing a regular building, Mahoney said.

The complex was built on a plot of land purchased from the city. The proceeds from the land sale will go toward renovations of public spaces such as the new Franklin Park plan.


Headshot of Paula Moura

Paula Moura Reporter, Climate and Environment
Paula Moura was a reporter on WBUR’s climate and environment team.



More from WBUR

Listen Live