Recent advances in numerical tools and data for the study of urban microclimates have helped to evaluate countermeasures for urban heat in heterogeneous and high-rise cities such as Hong Kong. Thus, two ventilation strategy designs, point ('oases') and linear ('corridors') features, were numerically simulated during a typical heatwave using the multi-layer coupled MesoNH-SURFEX-TEB mesoscale atmospheric model.

These strategies proved to be effective at night with respect to thermal comfort but caused a localised increase in heat stress during the day in the ventilated areas, which were less shaded. There was no significant deterioration in the wind performance around the developments that were redesigned to accommodate the displaced population due to the construction of the ventilation features; however, an improvement was observed in thermal comfort during the daytime. The simulated impacts were relatively localised, suggesting the importance of increasing porosity across the entire urban fabric. The corridors, especially when built along the axis of the prevailing winds, exhibited better ventilation at the pedestrian level than the oases. Nevertheless, the oases remain interesting features in the context of progressive urban ventilation planning that involve the implementation of isolated, connected, and eventually a network of features to provide benefits at the megalopolis scale.