The influence of vegetation and shade on thermal comfort perception among urban park users in the central European city – the case of Warsaw, Poland.

Urban parks are generally acknowledged to alleviate thermal stress, as they provide a cooling effect on hot days through transpiration and shading by tree crowns. However, in temperate climate their potential to improve residents’ thermal comfort varies throughout the year. Seasonal fluctuations in tree foliage and related changes in biothermal conditions will affect the perception of the thermal environment of green area users.

In this study we aim to determine how the thermal perception of Warsaw parks visitors varies depending on the type of vegetation and the shading it provides in the summer and transitional seasons. Almost 2800 respondents were surveyed in the six selected urban greenery complexes. In every location, thermal perception research and biometeorological measurements were carried out at least at two sites – in full sun and in the shade of trees. Individuals’ thermal comfort assessment and preferences towards particular weather elements were compared with measured meteorological parameters and UTCI values concerning the Sky View Factor, tree crown cover in a 50 m radius and vegetation types in each site. The possible impact of actual physical activity, thermal history and clothing of interviewees on their thermal sensations was also controlled. The biggest differences in thermal sensations (TSV) between sun-exposed and shaded locations were recorded in the summer – shade decreased perceived thermal conditions by approximately 0.5 point on the 7-point scale.

The results of our study provide a better understanding of how different park arrangements can affect residents' thermal perception and can help city authorities design and revitalize green areas to better adapt to climate change in the temperate climate zone.