The effect of urban green and blue on mitigating urban heat islands and improving thermal comfort: a case-study in Leuven, Belgium

High air temperatures form a significant problem for human health, leading to an excess mortality of 6% or more than 2 000 extra deaths during the summers of 2003, 2006 and 2010 in Belgium alone. Projections show that climate change will induce increasing average air temperatures and will lead to an increased frequency and severity of heat waves. The consequences of these projections are even greater in urban areas where the urban heat island (UHI) effect can significantly increase air temperatures within the city center compared to their rural and more natural environment. The creation and enhancement of urban green and blue infrastructures (UGIs and UBIs) is one of the most promising solutions for mitigating urban heat through evaporation and shading. These cooling benefits are however highly affected by their spatial composition and configuration. Knowing the optimal spatial configuration of UGI and UBI would help managers and decision makers to plan and manage their urban green and blue in order to maximize their cooling effect. We know from previous research that a well-established urban green and blue infrastructure will lower urban air temperatures and consequently reduce human heat stress, but only a few studies have been able to quantify these heat-related health benefits. In this research we will therefore study the effect of the spatial composition and configuration of urban green and blue on heat mitigation in relation to human health and well-being. This will be done through a combination of remote sensing technology, a dense weather station network and citizens engagement across multiple spatial and temporal scales.