Cooling Strategies for the Effective Mitigation of Summer Thermal Stress in City Laneways

This study explored a range of cooling interventions suitable for city laneways where space for greening opportunities is constrained. Five individual cooling interventions namely, PVC shading, cool pavement, small canopy trees, green wall and water mist, as well as multiple combinations of these individual cooling interventions were tested in a narrow laneway in the temperate setting of Melbourne, Australia. The impact of various cooling interventions was assessed by evaluating microclimatic parameters—air temperature (Ta), relative humidity (RH), mean radiant temperature (TMRT)—alongside two thermal comfort indices, Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI). When each intervention was analysed individually, water mist was the best performing with Ta, PET and UTCI reduction. This was followed by PVC shading, small canopy trees and green walls. Cool pavement had the lowest Ta reduction and minimal thermal comfort impact. While green provided marginal reductions in thermal comfort indices, the effects were insufficient for standalone cooling. They were most effective when integrated with other cooling interventions. For example, when green walls were combined with water mist, a Ta reduction of 1.49 K and a TMRT reduction 2.57 K were obtained. The water mist system as an individual cooling intervention or as part of a combined intervention had an impact on Ta with a reduction of maximum 1.3 K and 1.76 K, respectively. The water mist had a UTCI reduction of 1.25 K, and the water mist combined with green wall had a PET reduction of 1.84 K. The novel contribution of this study to climate-sensitive urban design is the suite of practical, site-specific interventions for extreme summer conditions. These findings provide a framework for planners and designers to evaluate and implement optimal cooling strategies tailored to the unique microclimate demands of narrow urban laneways.