A clamshell roof made of Makrolon 15 PC sheet from Bayer MaterialScience, Pittsburgh, was used in the latest addition to the building that houses the San Francisco-based California Academy of Sciences which serves as a natural history museum, planetarium, leading-edge scientific center, and educational facility.
The original roof designed used a retractable fabric screen system to allow for ventilation and natural light for the piazza space below. While the fabric met those needs well, it did not provide sufficient protection from the elements. To maximize aesthetics, minimize structural costs, and protect against nature, the design was changed to a clear operable roof that would seemingly “disappear” when closed and require minimal structural support. This required a clear material with long-lasting weathering performance and extreme strength for earthquake resistance.
Makrolon 15 PC sheet was selected for the retractable panels in this new living roof design over glass because it required fewer structural stainless steel supports, while providing aesthetic and cost benefits. The piazza atrium’s retractable roof is made of two 18-by-48 foot sections. Each section consists of six panels supported by eight 66-foot-long rectangular tubes that arch up eight feet at the center of the arched tubes with an edge flap providing a weather-tight seal between them. When open, the panels rest on the sides of the roof opening. The open-air piazza’s functionality makes it a key contributor to the climate control on the main floor, as the Academy uses no mechanical heating or cooling for the space.
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