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An elliptical office building goes with the flow in Boston

Exterior design cuts waste, saves energy, says Building Team members.

August 17, 2018 |

The 121 Seaport building in Boston includes two floors of prime retail space, and a tree-lined promenade at its base. Image: CBT

121 Seaport, a 440,000-sf Class A office tower within Boston’s Innovative Seaport District, recently accepted its first tenant, with Alexion Pharmaceuticals leasing 150,000 square feet on floors three through eight. Internet of Things (IoT) technology provider PTC is leasing 250,000 sf, and will move in early next year, according to Skanska, this building’s GC, developer, and owner.

The 18-story building, which was completed this Spring, is distinguished by its elliptical exterior design that required 10% less facade, which helped reduce construction costs and waste. The shape also cuts the surface area of the building that’s exposed to the sun, so there’s less heat gain, which translates to 15% energy savings.

121 Seaport is targeting LEED Platinum certification.

Boston-based CBT designed the building. BD+C spoke with two of CBT’s Principals, Phil Casey and David Nagahiro, about this project, whose design began in 2014.

Casey says the Building team had to rethink what a seaport office building would look like. He notes, too, that the site dictated the shape and orientation of the building. For one thing, the building had to navigate around a corner of the site that intersected with a tunnel for the Boston’s Silver Line bus service, which connects the seaport to Logan Airport.

Part of the site is also within the Federal Aviation Administration’s zone for Logan, which limited the height of the building. “Moving the building outside of the zoning envelope was liberating,” says Nagahiro. (The completed building is just under 250 feet tall.)

The shape of the building creates an aerodynamic plane that minimizes the impact of wind, which meant that less lateral steel reinforcement was needed, and thereby improving the efficiency of the building’s floorplate.

The building's lobby is designed to give visitors and pedestrians a calming sense of place. Image: CBT


The building’s lobby is positioned toward Central Square, the Seaport’s green space, thereby cultivating a welcoming urban experience for pedestrians. “When you walk into the lobby, you know you’re in a different building,” says Nagahiro.

The building’s interior features include virtually column-free floorplates, elevated 10-ft ceilings, and access to outdoor terraces. Other amenities include 24/7 concierge service, a private fitness center, green roof over the 50,000-sf retail podium, and a rooftop terrace with striking views of the city.

At the base of this building is a 70-ft-wide promenade called Harbor Way with 20,000 sf of open space and an interactive walking museum. A parking garage underneath the building can accommodate 270 vehicles and 270 bikes.

Since launching its commercial development business in 2009, Skanska has invested nearly $500 million into sustainable developments in Boston. Aside from 121 Seaport, it has two other developments at the Seaport: 101 Seaport, the North American headquarters for the accounting and consulting firm PwC; and Watermark Seaport, a two-building 300,000-sf LEED Gold residential high rise with ground-floor retail, and 15,000 sf of indoor/outdoor space for residents that includes an 18th-floor sky deck.

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