Urban cooling: which façade orientation has the most impact on a microclimate?

Abstract Deploying solar reflective materials on urban surfaces is known as an effective heat mitigation strategy. Several studies have shown their cooling impacts; however, most of them have focused on rooftops rather than facades. The novelty of this paper is related to exploring the impact of each facade orientation on the corresponding microclimate and energy balance. High albedo materials were implemented on facades with different orientations to explore the potential of each facade. Computer simulations were employed to calculate the insolation of different facades, ground surface temperature, and surface energy balances. The simulations are done for the longest day of the year (21st of June) to have the maximum solar radiation on all facades. The results showed that east-west canyons receive 6 hours more direct sun than north-south canyons. This proved that eastern and western facades have the most impact on the microclimate. Cooling east and west facades led to the maximum net radiation reductions for the ground surface. Furthermore, north and south facades had negligible contributions to pedestrian thermal comfort. By understanding the role of each facade, designers and policy makers could deploy cooling materials more effectively on building surfaces.