Study On The Calculating Method Of Sky View Factor And Urban Heat Island Effect Analysis

In the traditional sense,urban heat island effect refers to the phenomenon that urban temperature is higher than suburban temperature.The reasons for this phenomenon are uneven artificial terrain,the decrease of vegetation,and the heat output caused by human activities.In recent years,many cities in China have been affected by the high temperature weather in summer.More extreme weather,such as extreme high temperature and heavy rain,has greatly reduced the comfort of cities.For the heat island effect of large cities,there are more complex changes and characteristics than before,such as more solar radiation absorption,more anthropogenic heat emissions,and a wider range of high temperature areas.Urban heat island effect is closely related to urban spatial structure.The proposed sky view factor can better reflect the complexity of urban space than two-dimensional method in describing urban spatial structure.This paper mainly studies the sky view factor.The concept and nature of the sky view factor are further interpreted and studied by theoretical research and computational analysis.According to the nature of urban heat island effect research,a new method of calculating the sky view factor is found from a new angle,and the urban heat distribution is analyzed by a new method.The main conclusions of this paper include the following aspects:1.Studying the shape and distribution of buildings in space is helpful to analyze the heat island effect,describing and measuring the spatial shape and distribution of buildings.Previous studies mainly focused on the ratio of building density to spacing and height.These factors can only be described in two dimensions,which is far from enough for the complexity of space.Sky view factor is a more appropriate description method.2.Because of the difficulty in calculating the sky view factor in the actual environment,the previous studies on the sky view factor are limited to the calculation of geometric values.In the study of urban heat island effect,we can just regard the radiation as solar radiation,so that the sky view factor can reflect both the openness of space and the energy gain.3.This paper presents a new calculation method,that is,the physical meaning of the sky view factor is reflected by the solar radiation obtained from the calculation area,which is referred to as the calculation method of the solar radiation area.Comparing with other methods,solar radiation calculation method has no limitation in the area of research.In the aspect of result presentation,solar radiation calculation method mainly outputs in the form of images,which can achieve the presentation of calculation results of continuous sky view factor in a larger area and upgrade from point to surface.4.The searching radius of the sky view factor is over 80 meters,and the floating of the sky view factor is stable.The calculation results of the above 150 meters have not changed.Therefore,the applicable range of the searching radius is 80 to 150 meters.The calculation results are effective,reliable and save time and resources.5.In the spatial distribution,the materials are the same,the arrangement is denser,the sky view factor is smaller,and the solar radiation is less or less;the building density is small,but the underlying surface material has a low heat absorption rate,the sky view The domain factor is large in geometry definition,but it is reduced in physical definition.