14 Shade Planning for America’s Schools Chapter 2 • Exposed roof supports may be attractive nesting sites for birds. Strategies to deter this should be incorporated into the building’s design. • Lighting will allow for evening use of the building. • To provide additional light during daytime hours, polycarbonate panels can be incorporated into the roof design and provide a great deal of light while blocking up to 99% of ultraviolet (UV) radiation. • No matter what type of design is selected, all buildings require maintenance. A maintenance schedule and estimated costs should factor into the design selection process. • In the design of the structure, efforts should be made to close off the view of the sky by extending the eaves as far as possible. If the sky can be seen by people under the structure, they are at risk for exposure to indirect UV radiation. • The design of any structure should ensure access for people with disabilities. • If the structure is to be used as a classroom or meeting room, the acoustics of the building should also be addressed. Outdoor classroom at Hermantown School Duluth, Minnesota Constructed by the Duluth Skyline Rotary Club as a gift to the Hermantown School District, the outdoor classroom is directly behind the Hermantown Elementary School. Besides serving as an outdoor classroom, the building is accessible to elementary school students during recess periods. According to Fred Majeski, the Superintendent of the Hermantown School District, the building, with its metal framing and roof and concrete floor, would have cost the school well over $25,000 to build, had it not been donated by the Rotary Club. Shade Cloth Structures Another strategy for providing shade on school grounds is the use of shade cloth or structural fabric supported by a framework or poles. This strategy often is used when the goal is to cover large play areas without employing extensive structural support. Shade cloth is typically a knitted or woven fabric that is rated as to how much sun is blocked. Transmission of the sun’s rays through the fabric depends on the tightness of the weave or knit, with more densely woven or knitted fabric blocking out more of the sun’s radiation. Fabrics with a looser weave transmit between 50% and 80% of the sun’s harmful rays and are typically designed for horticultural applications. Shade cloth that blocks 80% of solar radiation provides the approximate protective equivalent of sunscreen with a sun protection factor (SPF) of 6.7, whereas shade cloth that blocks 94% of solar radiation provides the approximate protective equivalent of sunscreen with an SPF rating of 15. Shade cloth rated to block 94% of solar radiation is the minimum that schools should consider.