Optimizing the Seasonal Shade and Ultraviolet Protection of a Suburban Playground by Utilization of the Playground Shade Index.

The Playground Shade Index (PSI) is introduced as a design metric for assessing the shade and solar ultraviolet (UV) protection provided by eight different cloth weave shade structures currently utilized in public playgrounds across a regional city located in southern Queensland, Australia. The PSI, expressing the ratio of available ambient solar UV exposure relative to the UV exposure received by a shaded 184 m2 playground surface over a whole day in midsummer and midwinter, is used to determine the best design and aspect of all eight existing structures. Unlike subjective shade audits that may only consider the type of shade structure, the number and characteristics of surrounding trees, and surface materials available at a given site, the PSI considers, in addition to previous factors, the available sky fraction and the direct solar UV contribution underneath the shade structure over a full day. By considering the in situ UV protection characteristics of the shade structure, the PSI has demonstrated its value as a robust design metric. Of the eight shade structure styles examined, this research presents the most likely structure best suited for UV protection over the two solar UV extremes in summer and winter, including optimal structure aspect.

The Playground Shade Index: A New Design Metric for Measuring Shade and Seasonal Ultraviolet Protection Characteristics of Parks and Playgrounds.

Current shading strategies used to protect outdoor playgrounds from harmful solar radiation include the placement of artificial cloth weaves or permanent roofing over a playground site, planting trees in proximity to playground equipment, and using vegetation or surface texture variations to cool playground surfaces. How and where an artificial shade structure is placed or a tree is planted to maximize the shade protection over specific playground areas, requires careful assessment of local seasonal sun exposure patterns. The Playground Shade Index (PSI) is introduced here as a design metric to enable shade and solar ultraviolet exposure patterns to be derived in an outdoor space using conventional aerial views of suburban park maps. The implementation of the PSI is demonstrated by incorporating a machine learning design tool to classify the position of trees from an aerial image, thus enabling the mapping of seasonal shade and ultraviolet exposure patterns within an existing 7180 m2 parkland. This is achieved by modeling the relative position of the sun with respect to nearby buildings, shade structures, and the identified evergreen and deciduous tree species surrounding an outdoor playground.