By Rebecca Miller
“With retractable windows operated by climate sensors, winding catwalks and a three-story sky garden, it’s among the boldest design and engineering efforts under way nationwide.” -Lizette Wilson, San Francisco Business Times, 12/9/06
“Most striking are its bold design and social agenda: Skip-stop elevators…and open stairs will foster interaction among employees, with the idea of creating a healthy office environment and a healthy culture.” -The Editors, Businessweek.com, 2006
Hailed as an unprecedented landmark of achievement by the architectural community, the San Francisco Federal building rises on the city skyline as a tribute to the cutting-edge technologies of value-engineering and environmental friendliness. The 18-story concrete structure soars with modern clean lines and sweeping glass expanses, but the façade is only a minute clue to the true triumphs of the design. A Government Services Administration (GSA) commissioned “green” building; the project was awarded to the architectural firm Morphosis under the stringent Design Excellence Program, and meets the highest standards of the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEEDS) program
•No biohazard products
•70% natural ventilation cooling
•Computerized lighting controls
•Perforated metal sunscreens provide shading
•50% slag-concrete mix
•Polished concrete flooring
Under the watchful eye of the GSA and the architectural community at large, the Federal Building was carefully designed and engineered to support the main LEEDS objectives and create a model work environment prototype. Towering in both size and community impact; many hope the project’s innovative design will inspire other buildings in the same tradition.
Highly energy efficient and sustainable, concrete was chosen as a key construction material for the building. “What I see from the architectural point of view is that the designers are trying to show earth’s raw material at its best,” comments Jack Bell, Director of Operations for Perfect Polish, the Tennessee firm chosen to provide the structure’s flooring application.The use of concrete throughout the structure substantially reduces energy consumption by reflecting sunlight and utilizing thermal mass for natural heating and cooling. In conjunction with a remote controlled natural ventilation system, the concrete frame will cool 70% of the Federal Building without the aid of air-conditioning. A unique mix of nearly white cement used in exposed columns, walls and ceilings lightens the concrete to more effectively utilize natural light, potentially reducing energy usage by 50%. LEEDS dictates materials selection as a primary program tenet and concrete, with its multiple environmentally friendly and energy efficient uses, fits the bill.
Over 55,000 square feet of polished concrete flooring completes the “green” interior, adding modern allure to the space. “The floors are the unifying element reflecting the beauty [of the structure]”, says Tim Christ, Morphosis principal and project manager.
The look of polished concrete floors, applied by Perfect Polish, Inc., (Norris, TN), was achieved through their dry-polish process called the Natural Wonder Floor System™, developed in 1998 by parent company Concrete Polishing Technologies. Utilizing unique diamond-leveling technology, the floors were mechanically coarse ground nearly one-quarter of an inch, eradicating all damage done to the flooring during the construction process and revealing the natural beauty of the stones already in the mix. “Problematic concrete damage from construction was mostly on the basement and ground levels,” says David Padgett, Vice-President of Marketing and Business Development at Perfect Polish, and this damage posed severe aesthetic issues which were solved by the initial grinding. “In spite of the extreme abuse that the floors suffered by remaining unprotected [during construction] your team has managed to produce a very convincing product,” comments Christ. The first pass also corrected construction irregularities around doors and elevator thresholds by evening adjoining surfaces. With the patches of delaminated concrete repaired, a non VOC impregnating hardener was applied to increase density while tightening and toughening the aggregate surface. The team then performed a second fine grit diamond polishing step; this step closed any remaining pores in the floor, transforming it to a nearly impermeable surface that is highly resistant to all contaminants including oil and water. After administering a final penetrating sealant the Natural Wonder Floor System was complete—finished with a beautiful low matte sheen that seamlessly reflects contemporary style and functionality.
Value-engineering, essentially using all building materials to full potential, is a hot topic in “green” circles. Padgett explains that polishing the existing concrete value-engineers by eliminating the need to bring in a secondary floor covering, thereby saving time, reducing expense outlay and defraying total resource usage. Concerning the sustainability and durability of concrete he makes a comparison to European structures that are hundreds of years old by asking the question, “What are they built with?” The answer, of course, is mortar stone—a material used since the advent of construction—and used today in the San Francisco Federal Building.
The Natural Wonder Floor System was recommended to Morphosis by the general contractor, Dick Morganti because, as Christ relates, the sophistication of the machinery means better quality control. “It has a higher level of finish, is more durable than other flooring applications, and is more cost effective” he adds.
At a savings of over 50% per-square foot when compared to top competition terrazzo flooring, polished concrete cut Federal Building costs by roughly $750,000 initially, not to mention long-term savings. While other types of industrial flooring, including paint, acrylic, urethane, and epoxy mortar cost as much in re-service as initial investment, polished concrete refurbish rates amount to only half of the original cost. And, unlike many other flooring applications which must be meticulously maintained year after year, the Natural Wonder Floor System will need to be refinished only every four to six years—meaning further sustained cost control for client GSA. Padgett adds, “We helped the general contractor by replacing terrazzo with polished concrete in the spec and kept him from being charged twice as much.” The highly price-efficient result was a durable and lovely finish of which Christ was pleased to report, “Better looking floors equal a happier client!”
Cost, however, was far from the only draw to the service of Perfect Polish, Christ cites management expertise and service as important factors. “We have been huge proponents of the approach that they used at the San Francisco Federal Building.” Completing the entire 18-story, 55,000 sq. ft.+ was no small management feat, especially considering that the Perfect Polish team was coordinating with many other subcontractors. Christ praised their work saying, “Jack Bell is, in our estimation, a miracle worker.” Though the non-hazardous nature of dry-polishing enabled the team to work simultaneously with other tradesmen and the floors may be walked on during the polishing process, it still took a tremendous amount of planning to accomplish the task at hand. “During the work coordination effort we created a schedule of values for every room on every floor,” says Padgett. This allowed Perfect Polish to mobilize fewer times and work effectively. The installation was so clean and environmentally-friendly that downtime was not required: once the Natural Wonder Floor System was complete, the area was put back into full service immediately. Impressed with both the process and outcome, Christ says, “We [Morphosis] will continue to spec polished concrete floors on any of our public jobs where the client can be made comfortable with a concrete flooring solution…[we] plan to continue recommending Perfect Polish to any architects in the US who are looking into ground, polished floors.”
Padgett’s remarks on the finished product include, “It’s an amazing thing to see the polished floors next to all the stainless steel and glass…it looks like the future.”