Congress Square, Boston
Adding a 7-story curtainwall to three 1900s-era bank buildings in downtown Boston, Arrowstreet’s design team sought a lightweight material to contrast the structures’ original granite and limestone façades. The firm’s solution is reflected in the sparkling jewel box, fabricated with Solarban 60 Starphire glass by Vitro Architectural Glass and featuring a trendy soffit design, that is now perched atop the newly conjoined office buildings.
“We felt strongly the materiality and massing of the new addition needed to be distinct from the existing buildings to preserve their original character,” explains Jason King, AIA, LEED AP BD+C, senior associate, Arrowstreet. “The custom unitized curtainwall system incorporates ultra-transparent Solarban 60 Starphire glass, providing striking views into and out of the building and allowing the addition to feel lighter above the weightier masonry building below.”
To integrate the 24-foot cantilevered glass box, the design bends inward along Congress Street, adjacent to Post Office Square, at the exact point where the 1904 and 1906 building façades connect beneath it. The faceted, angular design then extends downward through the existing building on the north façade, forming the building’s second entry point and connecting it to the popular boutiques and cafés located along Quaker Lane.
“While coordinating these faceted curtainwall panels with the existing structure was challenging, the result is a wonderful moment where the juxtaposition of old and new is no longer experienced from afar,” King adds.
Arrowstreet’s soffit scheme, which is a custom-designed fiberglass-reinforced plastic with a gold finish, conveys a deep, rich texture that enables the glass to float gracefully above the century-old masonry and complement the existing cornice line.
In addition to the glass box, Solarban 60 Starphire glass was installed in 2-story curtainwall sections adjacent to the buildings’ historical main entrance on Water Street. Because the original street-level windows were dark and faced with decorative metal grillwork, the beautifully crafted details of the interior lobby were hid- den from public view.
“By introducing Starphire glass at the ground level, we were able to showcase those historical elements and rebrand the building from dark and uninviting to bright and welcoming,” King says.
The Congress Square renovation consolidated three sets of elevators, restrooms and stairwells from three separate buildings into one central elevator core. By replacing the lightwell, previously obstructed by surrounding buildings, with Solarban 60 Starphire glass, the lobby was transformed into a bright, daylit, energy-efficient space.
The project features exterior roof decks on levels five, 10 and 17, providing beautiful garden-like spaces where tenants can work, meet and take breaks while enjoying fresh air and majestic views of Beantown. While indoors, employees also are afforded striking city views through the low-e-coated Starphire Ultra- Clear glass, which is 87 percent less green in color than ordinary clear glass.
When coated with Solarban 60 solar control, low-e coating, Vitro Architectural Glass’ low-iron glass delivers visible light transmittance of 74 percent while blocking 59 percent of the sun’s heat energy, helping it to create a balance of energy-saving daylighting and solar control.
SOLARBAN 60 STARPHIRE GLASS MANUFACTURER: Vitro Architectural Glass
PHOTO: Vitro Architectural Glass