The Manifold Challenges for Modeling the Urban Heat Island

Abstract Urban heat islands (UHIs) can have negative effects on cities. Under tropical climate and for large and high-dense mega cities like Singapore the elevated temperature levels yield to higher energy consumption for cooling, reduced outdoor thermal comfort, and a lowered quality of urban living in general. While modeling and simulation of UHIs has been done successfully for the temperate zone and cities of either dominantly flat roof-scape (i.e. in Europe) or repetitive urban layout (in the U.S.), the same approach cannot be applied to Singapore. Three-dimensional cellular automata (3D-CA) are here proposed as means to model the manifold vertical features, which are not sufficiently taken into account with current state-of-the-art methods: the heterogeneous high-rise landscape and convection as a major heat rejection mechanism. As we demonstrate 3D-CA enable a new approach of UHI modeling where traditional urban microclimate models fail and computational fluid dynamics are not applicable due to the large scale.