The 18-story San Francisco Federal building’s concrete structure is a Government Services Administration (GSA)-commissioned green building; the project was awarded to the architectural firm Morphosis under the Design Excellence Program. Concrete was chosen as a key construction material for the building for its energy efficiency and sustainability. In conjunction with a remote controlled natural ventilation system, the concrete frame will cool 70 percent 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 percent.

“What I see from the architectural point of view is that the designers are trying to show earth’s raw material at its best,” said Jack Bell, director of operations for Perfect Polish, the Tennessee firm chosen to provide the structure’s flooring application. The usage of concrete throughout the structure substantially reduces energy consumption by reflecting sunlight and utilizing thermal mass for natural heating and cooling. 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],” said Tim Christ, Morphosis principal and project manager.

The look of polished concrete floors, applied by Perfect Polish, Inc., (Norris, Tenn.), was achieved through the company's dry-polish process called the Natural Wonder Floor System, developed in 1998 by parent company Concrete Polishing Technologies. Utilizing 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. “Problematic concrete damage from construction was mostly on the basement and ground levels,” said David Padgett, vice-president of marketing and business development at Perfect Polish, and this damage posed severe aesthetic issues that were solved by the initial grinding.

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 low-matte sheen that reflects contemporary style and functionality.

Padgett explained that polishing the existing concrete eliminates the need to bring in a secondary floor covering, thereby saving time, reducing expense outlay and defraying total resource usage.

The Natural Wonder Floor System creates a durable floor that's elegant and requires low-maintenance.

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 added. At an estimated savings of over 50 percent per square foot when compared to terrazzo flooring, polished concrete cut Federal Building costs by roughly $750,000 initially, not to mention long-term savings. Polished concrete refurbish rates can amount to only half of the original cost, and, unlike other flooring applications that must be meticulously maintained year after year, the Natural Wonder Floor System will only need to be refinished every four to six years, the company reports.

The Perfect Polish team was coordinating with many other subcontractors, and though the non-hazardous nature of dry polishing enabled the team to work simultaneously with other tradesmen and the floors to be walked on during the polishing process, it still took a tremendous amount of planning to accomplish the task at hand. Once the Natural Wonder Floor System was complete, the area was put back into full service immediately.