Vegetation structural complexity is a key driver of thermal comfort in small parks. Small urban greenspaces can deliver significant cooling benefits when the vegetation structure includes tall trees and dense shrubs. The modelling of 12 diverse small parks (< 2 ha) in Munich, Germany, showed that, depending on vegetation structure, perceived heat could drop by up to 16°C compared with surrounding built‑up areas. Such a reduction can shift conditions from extreme to slight heat stress in the summer, and highlights the importance of plant design choices for public health.
The cooling potential of greenspaces is commonly reported to increase with size. However, this research demonstrates that cooling potential is also strongly affected by vegetation structure, particularly in small greenspaces. Depending on the vegetation structure a reduction in the heat experienced was achieved by up to 16°C compared to built surroundings. The research developed models based on field measurements and high-resolution vegetation structure to analyse the modified Physiologically Equivalent Temperature (mPET) in central Munich. Vegetation structure was derived from mobile terrestrial laser scanning and combined with sky view factor estimates from hemispherical photographs and micro-meteorological measurements. A change in mPET, such as the 16°C reduction estimated in this research, can translate into a shift from extreme heat stress (> 41 °C mPET) to slight heat stress (23–29 °C mPET). This observed difference can be vital in assessing the impact on a person’s experience of heat in urban areas. However, the research also showed that thermal cooling effects varied greatly between greenspaces, and some greenspace plots provided little to no thermal cooling, or even demonstrated slight warming, compared to the surroundings.
Tree height and shrub density were found to be key factors in the differences in thermal outcome. Greenspace plots with tall, multi-layered vegetation provided strong heat buffering, whereas sparsely vegetated plots offered little to no thermal relief. Overall, shrubs appear to mitigate heat not primarily through shading, but by lowering ground heat storage, increasing evapotranspiration, and modifying air circulation.
Small greenspaces with structurally complex vegetation can substantially reduce air temperatures and may even benefit the local microclimate more than large parks with predominantly grassy areas and low structural complexity, though the effect is variable. Actions such as protecting mature trees, reducing sky openness, and integrating shrub layers can create powerful assets from compact greenspaces for mitigating urban heat in dense city environments.
Arzberger, S., Burger, S., Egerer, M., Suda, M. and Annighöfer, P., 2026. Thermal comfort during hot days in Munich, Germany: How does vegetation structure in small urban greenspaces matter?. Sustainable Cities and Society
