Comparing the annualised dynamic shade characteristics of twenty-one tree canopies across twenty-six municipalities in a high ambient UV climate, Queensland - Australia

Standardised assessments comparing the surveyed shade quality characteristics of twenty-one trees currently established and growing in public parks and playgrounds in Queensland, Australia are presented for informing local government, shade designers and municipal planners. Assessments focus on the ultraviolet protection of individual tree canopies which are reported in terms of the Shade Protection Index (SPI) and Ultraviolet Protection Factor (UPF) assessed at fine temporal resolution and averaged over a full calendar year. The UPF and SPI are used to determine tree species best suited for optimal shade with respect to twenty-six regional cities spanning 17∘ in latitude. This assessment included all local coastal districts from Bamaga (−10.89∘ S, 142.39∘ E) to Southport (−27.97∘ S, 153.42∘ E) showing a general (species dependent) decline in ultraviolet protection with increasing southerly latitude. Survey tree species are ranked and listed in order of best ultraviolet protection for respective localities enabling the quality of protection provided by living tree canopies to be compared across a range of environments

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