Microclimate measurements for quantifying climate adaptation impact of urban redevelopment

It is well established that ongoing climate change is leading to more heat stress events, which have a significant negative impact on public health. This is especially the case for urban environments, where the largest portion of the population lives and, depending on the metric, increased levels of heat stress can be found. Depaving cities and implementing green- and blue infrastructures (GBI) results in less heat accumulation, lowering the urban heat island (UHI) effect, and the shade of tree canopies act as a buffer for extreme temperatures during the day. 

The implementation of these solutions is, however, less evident in practice, due to the complexity of the urban redevelopment process. A plethora of aspects play an important role in (re)design, planning and construction, and more traditional concerns - such as mobility, accessibility, and maintenance - are often prioritized over human thermal comfort. Tools and evidence-based knowledge are needed to emphasize the value of climate adaptive design and nature based solutions such as GBI. The value of these tools for urban redevelopment professionals lies, for example, in their ability to visualize and quantify the impacts of climate-related hazards, both with and without GBI, thereby demonstrating GBI’s potential to mitigate these hazards while preserving priority functions. 

In the urban development field, many tools are available for professionals active in different aspects of the urban (re)development process. The most applicable type of tools to directly assess the future heat mitigation impact of a design are microclimate models, such as ENVI-Met and UMEP. However, when these tools are used to compare current and future urban environments, there is a lack of observations to validate the outcome of these models. The main reason for this lack is the complexity of such a measurement campaign. Besides common technical issues regarding sensors, data logging and long-lasting measurements in public spaces, multiple other practical difficulties arise, mainly related to practical feasibility, variability, comparability, and, most notably, time. 

This study presents an attempt to undertake this kind of measurement campaign. Three urban areas in three different Belgian cities were redeveloped for the benefit of climate adaptation. Four microclimate stations were placed in each location, both before and after redevelopment, with the goal of observing changes in microclimate and, more specifically, investigating the role that the newly implemented GBI play in these changes. Three stations were placed to measure a representative microclimate both before and after redevelopment, while a fourth was placed outside yet close to the project area where no changes occurred, to serve as a reference. 

This presentation will focus on the practical and technical implementation of these measurement campaigns. Difficulties and limiting factors will be highlighted. Moreover, based on the conducted measurements, it will be shown how urban redevelopment and GBI can be evaluated based on their impact on thermal comfort.