Numerical and experimental study on integrated strategic simulation model of urban environment

城市地区的小气候参数对建筑物的能源性能和被动冷却措施的潜力有重要影响。例如，城市热岛效应导致城市地区的局部大气和地表温度比周围农村地区高。因此，城市热岛将增加过热的风险和建筑物的峰值冷负荷。在炎热的天气期间，它可能特别对城市热岛内的夜间降温策略产生负面影响。有效的城市规划和建筑设计可以对城市气候产生有益的影响，并有助于降低城市热岛的强度，从而改善生活空间的条件，并直接降低建筑物的峰值冷负荷。该项目的愿景是通过使用数字单元模型（DEM）存储城市建筑物的几何形状和边界信息，并将其与耦合的热和气流模型相结合，开发出一种实用的、鲁棒的城市热模拟方法。DEM是一种使用高程值的2D矩阵存储3D信息的紧凑方式;每个像素代表建筑物高度，并可以显示在灰色阴影的数字图像中，其灰度与城市表面的水平成比例。DEM能够在更短的时间内处理大量的数据。它还能够呈现研究区域内建筑物之间的几何关系。它已被证明是一种有效的城市分析方法。该模型将用于对城市形态和纹理、建筑和路面材料以及植被的各种配置进行参数研究，以分析城市热岛（UHI）缓解策略和节能建筑的潜在被动措施。本计画为期三年，主要目的为：（1）发展一个结合数位单元模式（DEM）的热力与气流动态耦合的都市模式，并结合都市峡谷的实验研究来验证此模式;（2）将建议的数值城市模型与现有的热量和气流建筑物模型连接起来（由PI制定），以分析城市微气候与建筑物能源性能的相互关系;（3）进行城市参数研究，分析城市热岛缓解策略的潜力及其对城市环境和能源消耗的影响（4）评价城市和建筑热舒适性。预期交付成果为：第一天：一个与数字单元模型（DEM）相结合的热力和气流耦合城市动态模型，以及一系列用于城市环境分析的不同城市配置的数值和可视化模拟结果; D2：一个综合的城市微气候和建筑物能源模拟模型; D3：一系列用于城市环境和城市热岛缓解策略潜力的参数评估; D4：城市环境中节能建筑设计被动措施的一系列评估。

The microclimate parameters in urban areas have important impacts on the energy performance of buildings and the potential of passive cooling measures. For example, the urban heat-island (UHI) effect results in increased local atmospheric and surface temperatures in urban areas compared to the surrounding rural areas. Thus, the UHI will increase the overheating risk and the peak cooling load of buildings. It may particularly have a negative impact on night cooling strategies within the UHI during periods of hot weather. Effective urban planning and building design can have a beneficial effect on the urban climate and contribute towards reducing the intensity of the urban heat island, which improves the conditions in living spaces as well as directly reducing the peak cooling load of a building. The vision of the proposed project is to develop a practical, robust, urban thermal simulation method by using Digital Element Model (DEM) to store urban building geometry and boundary information and integrating it with the coupled thermal and airflow model. The DEM is a compact way of storing 3D information using a 2D matrix of elevation values; each pixel represents building heights and can be displayed in a grey-shaded digital image, which has a grey-level proportional to the level of the urban surface. The DEM is capable to handle large amount of data in less time. It is also able to present the geometrical relations among the buildings in the studied area. It has been proven to be an effective way of urban analysis. This model will be used to perform parametric study for various configurations of urban form and texture, building and road surface materials and vegetation in order to analyse Urban Heat-Island (UHI) mitigation strategies and potential passive measures of energy-efficient buildings. The principal objectives of this proposed three-year project are: (1) To develop a dynamically coupled thermal and airflow urban model integrating with the Digital Element Model (DEM), and to validate the model in association with experimental investigations in the urban canyon; (2) To link the proposed numerical urban model with the existing thermal and airflow building model (developed by the PI) to conduct an analysis of the interrelationship of the urban microclimate and building energy performance; (3)To perform an urban parametric study and analyse the potential of UHI mitigation strategies and their impact on the urban environment and energy consumption (CO2 emission) and (4)To assess urban and building thermal comfort. The prospected deliverables are: D1: A coupled thermal and airflow urban dynamic model integrated with the Digital Element Model (DEM) together with a series of numerical and visualised simulation results of different urban configurations for urban environment analysis; D2: A integrated urban microclimatic and building energy simulation model; D3: A series of parametric assessments for the urban environment and the potential of UHI mitigation strategies and D4: A series of assessments for passive measures of energy-efficient building design in the urban context.