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A Seismic Advance in Performance

181 Fremont was engineered for performance, including a unitized curtainwall featuring Solarban® 70XL solar control low-e glass.

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September 06, 2019 |

Pre-certified as LEED® Platinum, 181 Fremont is fully glazed with Solarban® 70XL Glass (now Solarban® 70 Glass) by Vitro Architectural Glass.

Designed to be the most resilient tall condominium on the West Coast, every square-inch of 181 Fremont’s 435,000 square-feet was engineered for superior performance, including the innovative, unitized curtainwall system.

Pre-certified as LEED® Platinum, 181 Fremont incorporates a floor-to-ceiling façade designed to enhance the energy performance of the 55-floor, mixed-use tower, fully glazed with Solarban® 70XL Glass (now Solarban® 70 Glass) by Vitro Architectural Glass—an advanced, triple-silver-coated, low-emissivity (low-e) glass that blocks 73 percent of the sun’s heat energy in a 1-inch insulated glass unit (IGU) while still enabling 64 percent of daylight to pass through.

The design by Heller Manus Architects creates a sawtooth pattern with angled window mullions that face slightly inward against one another throughout the curtainwall that acts as a passive solar control system. The low-e glass accentuates the performance of the angled window mullions, which function as shading devices.

Glazing contractor Benson Industries Inc. took an active role in working through the complex glass geometry. As the glass fabricator, Hartung Glass Industries, a member of the Vitro Certified™ Network, worked closely with Benson Industries to make the project a success.


Solarban® 70 Glass blocks 73 percent of the sun’s heat energy in a 1-inch insulated glass unit (IGU) while allowing 64 percent of daylight to pass through.


“With the proposed sawtooth adjoined diagonal panels, it created hundreds of unique curtainwall units,” said Jeffrey Heymann, vice president of business development for Benson Industries. “Each unique unit had its own 3D model, where the connections and milling could be studied in depth.”

With the steel exoskeleton, the diagonal elements required retention cages that encroached on a typically clear anchor zone. Getting the right fit took several months of modeling, yet the finished result can handle high wind forces and seismic events up to 8.0 magnitude.

To dissipate wind forces along the glass-walled amenity terrace located about 500 feet from the ground, the tower embodies an open, chevron-shaped midway. Due to the open nature of the terrace, wide panels of Solarban® 70XL glass were required to achieve the prescribed level of wind deflection.

To maximize resilience, engineers used a 44-caisson system with a series of dampers to conserve the structural weight. Individual caissons were driven an average of 262 feet into the ground to enhance structural and non-structural design to limit damage and improve egress systems—earning it a Resilience-based Earthquake Design Initiative (REDi™) Gold rating.

Occupant Evacuation Operation (OEO) elevators were used in place of stair towers, maximizing availability of office and residential leasing space.

Completed in May of 2018, 181 Fremont includes 435,000 square feet of Class A office space and 17 floors of luxury condominiums—including a $42 million penthouse. The building’s office space has been fully leased by Facebook. In addition, homeowners have purchased almost all of the dozen residential units, which offer bridge-to-bridge views of San Francisco and the Bay.

To learn more or request a sample of Solarban®70 Glass, visit 

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