# Impacts of urban adaptation on reducing temperatures and heat-related deaths in Belgium

## TL;DR

This study shows that urban adaptation strategies like cool roofs and vegetation can significantly reduce heat and heat-related deaths during extreme heatwaves in Belgium.

## Contribution

The study quantifies the effectiveness of urban adaptation strategies at city- and country-scale during a real heatwave in a highly urbanized region.

## Key findings

- Cool roofs could reduce daily maximum temperatures by 2.1°C during heatwaves.
- Combining cool roofs with 20% more vegetation could lower daily minimum temperatures by 1.7°C.
- Compact urban areas benefit most from cool roofs, while open areas benefit more from vegetation at night.

## Abstract

•A quarter of heat-related deaths during July 2019's heatwave could have been prevented with adaptation strategies.•A great fraction of the population is exposed to the highest temperatures, but these temperatures can be reduced the most.•Urban morphology strongly affects cooling potential of heat adaptation strategies.

A quarter of heat-related deaths during July 2019's heatwave could have been prevented with adaptation strategies.

A great fraction of the population is exposed to the highest temperatures, but these temperatures can be reduced the most.

Urban morphology strongly affects cooling potential of heat adaptation strategies.

Extreme heat poses increasing risks to urban populations, yet the effectiveness of adaptation strategies at larger scales beyond neighbourhoods remains poorly quantified. The July 2019 heatwave in northwestern Europe, one of the hottest on record, offers a unique opportunity to evaluate city- and country-scale interventions in Belgium, in one of the world’s most urbanised mid-latitude regions. Using high-resolution urban climate modelling, we investigated the benefits of adaptation strategies on urban air temperatures. Our modelling of urban air temperatures suggests that the widespread deployment of cool roofs could reduce daily maxima by 2.1 °C, while combining them with a 20 % relative increase in vegetation could lower daily minima by 1.7 °C. Here, we found substantial temperature differences between compact and open urban areas and, subsequently, in population exposure to extreme heat. Furthermore, we estimate that the implementation of cool roofs could have avoided around a quarter of all heat-related deaths during this extreme heatwave event in Brussels. Our results show that adaptation strategies must be tailored to local urban characteristics to achieve substantial reductions in temperature and mortality, with more compact urban areas benefiting most from cool roofs during the day while the combination of cool roofs and increased vegetation has more impact on reducing nighttime temperatures in open urban areas.