15 Shade Planning for America’s Schools Chapter 2 Sun Protection Factor (SPF) What Does SPF Mean? The common interpretation is how much longer skin covered with sunscreen takes to burn as compared to unprotected skin. Sunscreens can be rated for their protective factor against either UVA or UVB radiation or both. The thickness and thoroughness of application, the type of sunscreen, and the frequency of reapplication factor into whether or not sunscreen delivers the protection for which it is rated. Advantages • Can be relatively inexpensive to construct. • Generally requires minimal upkeep. Disadvantages • Provides varying UV radiation protection. • Can be susceptible to weather damage. • Has a shorter life span than solid roof structures. Considerations • Because the UV protection qualities of shade cloth and other structural fabrics vary widely, care should be taken in determining the most appropriate fabric. • Care must be taken in the positioning of supporting posts so that they do not create a danger to children at play. • As with any other structure, one of shade cloth should be positioned for maximum sun protection. • The structural integrity of a fabric structure is related to its curvature and positioning. Structures must be designed to withstand the snow and wind loads that can be expected in their locations. • The design and installation of these structures should be left to specialists. Names and contact information of organizations that design and install fabric shade structures can be found at the end of this chapter. Natural Shade Incorporating natural shade into the overall design offers several advantages. The best approach to creating shade is one that provides protection from the sun’s harmful radiation during the spring, summer, and fall, yet does not completely block the sun’s warmth during winter months. Incorporating deciduous trees, shrubs, and vines into the design provides the seasonal variation in protection that structures alone cannot provide. Likewise, evergreen trees, vines, and shrubs planted alongside structures can serve to block wind in the winter and provide protection from scattered UV radiation during the rest of the year. Advantages • Reduces the ambient temperature more so than structures. • Provides seasonal sun protection. • Provides low-cost alternatives. • Improves the aesthetics of the school grounds. • Provides an opportunity for students to learn about nature.