Advancement in Urban Climate Modelling at Local Scale: Urban Heat Island Mitigation and Building Cooling Demand

Abstract

As cities and their population are subjected to climate change and urban heat islands, it is paramount to have the means to understand the local urban climate and propose mitigation measures, especially at neighbourhood, local and building scales. A framework is presented, where the urban climate is studied by coupling a meteorological model to a building-resolved local urban climate model, and where an urban climate model is coupled to a building energy simulation model. The urban climate model allows for studies at local scale, combining modelling of wind and buoyancy with computational fluid dynamics, radiative exchange and heat and mass transport in porous materials including evaporative cooling at street canyon and neighbourhood scale. This coupled model takes into account the hygrothermal behaviour of porous materials and vegetation subjected to variations of wetting, sun, wind, humidity and temperature. The model is driven by climate predictions from a mesoscale meteorological model including urban parametrisation. Building energy demand, such as cooling demand during heat waves, can be evaluated. This integrated approach not only allows for the design of adapted buildings, but also urban environments that can mitigate the negative effects of future climate change and increased urban heat islands. Mitigation solutions for urban heat island effect and heat waves, including vegetation, evaporative cooling pavements and neighbourhood morphology, are assessed in terms of pedestrian comfort and building (cooling) energy consumption.

Urban Heat Island and Its Interaction with Heatwaves: A Review of Studies on Mesoscale

“…In order to mitigate the negative effects of UHI, especially during HWs, numerous strategies have been proposed, such as using permeable pavements [31][32][33] and reflective materials [34,35], increasing vegetation cover [36][37][38][39][40][41][42] and so on. Susca et al [43] evaluated the effectiveness of using vegetation for UHI mitigation in New York City and reported a positive impact since vegetation effectively reduced the building cooling/heating load and the consequent building energy consumption.…”

Representative meteorological data for long-term wind-driven rain obtained from Latin Hypercube Sampling – Application to impact analysis of climate change

“…Buildings further away are not explicitly modeled, but their effects are imposed as ground roughness, as clarified in Section 4.2.1. Such threelevel spatial definition of geometrical details is commonly applied [40].…”

Green roof evaluation and comparison during summer in Central Europe climate

“…Most green roof benefits are connected with the summer, such as reduction of the urban heat island intensity and summer overheating of interiors, rainwater retention and evapotranspiration, dust particles collection, fire safety, various architectural and aesthetic aspects, etc. Effort of researches can be divided into several fields concerning the benefits: reducing the runoff volumes to the drainage network [6][7][8], storm water management [8,9], increasing the green areas within the cities to mitigate the Urban Heat Islands (UHI) [10,11], wetting individual surfaces and more complex simulation of urban environment [12].…”