Comprehensive studies comparing impacts of building and street levels interventions on air temperature at metropolitan scales are still lacking despite increased urban heat-related mortality and morbidity. We therefore model the impact of 9 interventions on air temperatures at 2 m during 2 hot days from the summer 2018 in the Greater London Authority area using the WRF BEP-BEM climate model. We find that on average cool roofs most effectively reduce temperatures (∼−1.2°C), outperforming green roofs (∼0°C), solar panels (∼−0.5°C) and street level vegetation (∼−0.3°C). Application of air conditioning across London (United Kingdom) increases air temperatures by ∼+0.15°C. A practicable deployment of solar panels could cover its related energetic consumption. Current practicable deployments of green roofs and solar panels are ineffective at large scale reduction of temperatures. We provide a detailed decomposition of the surface energy balance to explain changes in air temperature and guide future decision-making.

A. Martilli (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas), J. Taylor (Tampere University), M. Davies (University College London), C. Heaviside (University College London)

Brousse, O., Simpson, C., Zonato, A., Martilli, A., Taylor, J., Davies, M., & Heaviside, C. (2024). Cool roofs could be most effective at reducing outdoor urban temperatures in London (United Kingdom) compared with other roof top and vegetation interventions: A mesoscale urban climate modeling study. Geophysical Research Letters, 51, e2024GL109634. https://doi.org/10.1029/2024GL109634