Overheated children's playgrounds in Central European cities: The effects of surfaces and shading on thermal exposure during hot summer days

Abstract

Thermal exposure in children's playgrounds is a specific issue in relation to outdoor thermal comfort. In moderate climate regions, playgrounds are prone to overheating on hot summer days. When aiming for a safe design for playgrounds, different thermal conditions with various active surfaces and shading solutions, both natural and artificial, should be considered. Twelve case studies were performed in four Czech cities to quantify the differences in thermal exposure between individual types of active surface and shading, using mean radiant temperature and the biometeorological indices UTCI and PET (plus its experimental child-specific adjustments) as an expression of the thermal environment on hot summer days. The highest thermal exposure appeared above gravel, followed by rubber. Nevertheless, apart from a slightly lower thermal exposure above maintained lawn, substantial positive microclimatic effect of natural surfaces, such as bark mulch, sand, or a small water pool, was not confirmed. In terms of shading, trees provide more pronounced cooling effect than shade sails, but even the latter are effective in substantially reducing heat stress. Analyses of experimental adjustment of PET further indicate the importance of considering the specifics of a child's organism and behavioural adaptation measures when addressing thermal comfort and heat stress in playgrounds.