Urban heat island mitigation in Singapore: Evaluation using WRF/multilayer urban canopy model and local climate zones

Abstract Mitigation and adaption measures must be designed strategically by urban planners, designers, and decision-makers to reduce urban heat island (UHI) related risks. We employed the Weather Research and Forecasting (WRF) model to assess UHI mitigation scenarios for the tropical city of Singapore during April 2016, including two heat wave periods. The local climate zones for Singapore were used as the land use/land cover data to account for the intra-urban variability. The simulations show that the canopy layer UHI intensity in Singapore can reach up to 5 °C in compact areas during nighttime. The results reveal that city-scale deployment of cool roofs can provide an overall reduction of 1.3 °C in the near-surface daytime air temperature in large low-rise areas. Increasing the thermostat set temperature to 25 °C from 21 °C in city-wide buildings can potentially reduce the air temperature due to less (~20%) waste heat discharge from air-conditioning units. A densification scenario considering an increase from approximately 7 841 people/km2 (2016) to 9040-9,600 people/km2 (2030) under the current climate leads to air temperature increase of 1.4 °C, which demonstrates the importance of limiting the densification of less compact areas in maintaining thermal comfort in the future.