Additional daylighting and delivery of 100% filtered outside air are two benefits of placing utilities under a raised-floor system.
At 30 stories and 450,000 sq. ft. of commercial office space, 350 Mission Street is situated at the corner of Mission and Fremont Streets, directly across the street from the new Transbay Transit Center in downtown San Francisco. While not the tallest building in the city skyline, it’s definitely one of the most ambitious. The first LEED-Platinum-certified highrise in the city, 350 Mission Street was designed with sustainability at the forefront of every decision. In fact, Chris Heimburger, senior vice president of development for Kilroy Realty Corporation & Management, San Francisco, described the project goal as the creation of a “high-performance work environment” in every aspect, from employee performance to optimized operating costs.
While several sustainable strategies were used in the design, including high-performance insulated glass as part of the building’s cladding, rainwater harvesting, and gray-water recycling for non-potable uses, it was the access floors that provided several of the keys to creating a truly modern and sustainable facility.
Designing the project with an access-floor system from Tate Inc., Jessup, MD, made it possible to place multiple services, including cables, piping, and ductwork, under the floor. Moving services under the floor allowed the building’s concrete ceilings to remain exposed, creating an 11-ft. floor-to-ceiling height, which increased overhead space for employees and provided room for larger windows to improve daylighting. Additionally, using an under-floor air-distribution (UFAD) system allowed 100% filtered outside air to be brought into the building and distributed in an energy-efficient manner.
Saied Nazeri, principal-in-charge for engineering firm WSP, Montreal, said, “In addition to sustainability concerns, it was important to provide flexible office space. Under-floor air is a great way to meet both demands and was the best means to achieve the project goals.” UFAD, combined with other energy-conservation strategies, is expected to reduce energy costs by about a third.
In addition to helping achieve sustainability and energy-efficiency goals, the access-floor system fit seamlessly into the aesthetic vision that was developed for the building interior.
The top four floors comprise a group of executive suites and meeting spaces that needed to convey a high-end professional feel while maintaining the access-floor benefits. To achieve this, architecture firm Mark Cavagnero Associates, San Francisco, developed a free-flowing conceptual design with specific material requirements, including teak plank wood and multi-piece porcelain. Vendors then used custom engineering and manufacturing capabilities to produce a factory-laminated hybrid panel solution that features a curved transition. The hybrid panels arrived ready for installation and provide a seamless transition from one finish to the other on a single panel without sacrificing any accessibility to the under-floor services.