Modeling of rooftop mitigation strategies in arid climates based on local climate zones using WRF

Rapid urbanization and extreme heat pose growing energy and thermal comfort challenges for citizens living in arid cities such as Riyadh. Rooftop-based heat mitigation strategies are being deployed across cities as potential mitigation solutions to extreme heat. However, the city-wide temperature reduction achieved by rooftop strategies under arid conditions remains inadequately quantified across different urban morphologies. This study employs Weather Research and Forecasting (WRF) with the urban canopy model (UCM) to evaluate the cooling potential of cool roofs, green roofs, and rooftop photovoltaic (PV) systems during a six-day heatwave event in Riyadh. The Local Climate Zone (LCZ) framework is used to differentiate rooftop mitigation performance across urban morphologies. The post-processing analysis evaluates air temperature, surface temperature, and surface energy fluxes across the different scenarios. Results indicate that daytime surface temperatures are reduced by up to 1.23 °C for green roofs and up to 4.62 °C for super cool roofs relative to the base case, with the strongest cooling observed over compact low-rise LCZs. Cool roofs also produce substantially lower sensible heat fluxes than green roofs across all urban LCZ Categories. Green roofs provide localized evaporative cooling benefits but are less effective than cool roofs at reducing city-wide temperatures under arid conditions. The results also show that cooling benefits vary across LCZs, with compact low-rise neighborhoods showing the greatest temperature reductions. Overall, the findings demonstrate that modeling frameworks that integrate LCZs and WRF simulations can inform evidence-based rooftop mitigation strategies to enhance heat resilience in arid climates.