Heat Mitigation in Cities: A Catalyst for Building Energy Saving

Abstract

Overheating of cities increases the cooling energy consumption of buildings and the corresponding peak electricity demand. Advanced urban heat mitigation technologies that involve the use of super cool photonic materials combined with properly designed green infrastructure, lower the urban ambient and land surface temperatures and reduce the cooling energy consumption at the city scale. Here, we present and report the results of the world’s largest heat mitigation project in Riyadh, KSA. Daytime radiative coolers as well as cool and super cool materials combined with irrigated or non-irrigated greenery, have been used to design eight holistic and integrated heat mitigation scenarios, properly assessed by mesoscale climatic models covering the whole city. We assessed the impact of the scenarios as well as the corresponding energy benefits of 3323 urban buildings. An impressive decrease of the peak ambient temperature, up to 4.5°C, is calculated, consisting of the highest reported urban cooling performance, while the cooling degree hours in the city decrease by up to 26%. We found that innovative urban heat mitigation strategies contribute to remarkable cooling energy conservation by up to 16%, while the combined implementation of heat mitigation and energy adaptation technologies result in a decrease in the cooling demand by up to 35%. It is the first article investigating and reporting the large-scale energy benefits of modern heat mitigation technologies implemented in large cities as well as the dynamic and complex interdependencies between urban buildings and the urban environment as well asthe suitability and the corresponding cooling and energy conservation potential of current and advanced heat mitigation technologies. It finally explores pathways to optimise urban heat mitigation and the related energy conservation strategies in cities.