Physical and Geographical Analysis of Urban Heat: the Urban Cooling Potential Indicator

The performance of a number of urban cooling techniques has been thoroughly studied by the scientific community. However, decision-makers lack simple tools to spatially analyze their deployment as part of their urban cooling and climate change adaptation strategies. Among other indicators, a spatial assessment of the cooling potential of a given area is lacking.

To this end, we analyze the physical mechanisms on which these techniques are based and identify corresponding geographical indicators that influence their cooling performance. Depending on the cooling target, different energy balance equations are relevant. Solar irradiance, existing material properties and urban vegetation stand out as essential indicators for this purpose. These data also offer the advantage of often being easily accessible at high spatial resolutions by urban stakeholders. A simple empirical combination of these parameters is proposed for the analysis of daytime Urban Cooling Potential (UCP) which can be analyzed using GIS software.

Over the last ten years, our team has evaluated urban cooling techniques for approximately 20 different sites under radiative conditions, with fixed and mobile weather station monitoring, while the UCP has been mapped for a number of these sites.

In this communication, the UCP indicator will be presented and compared with daytime microclimatic measurements conducted at several monitored sites, in particular those studied during the ERDF UIA OASIS project, where ten schoolyards were monitored before and after transformation to evaluate the cooling effects of their transformation. The correlation of UCP and relative heat stress levels is discussed as well as paths for improvement of the UCP indicator as well as certain use cases by municipalities.