Investigation Of Model And Influence On Urban Heat Island Intensity In Mid & High-density Urban Residential District

The rapid development of the city has changed the original underlying surface,which change the energy balance of the region,resulting in a higher temperature in the city than in the suburbs.With global warming,the urban heat island effects（UHIs）has led to frequent extreme weather,and the characteristics of outdoor thermal and humid environment in urban are significantly different from those of the suburbs.It has a certain negative impact on residents’thermal health,building energy consumption,and building thermal design.An accurate understanding of the characteristics and causes of the UHIs is a prerequisite for dealing with the negative effects of the UHIs.Due to the natural causality among the various influencing factors of the UHIs,traditional statistical analysis methods are often difficult to separate the influence of a certain factor.The causal relationship between the UHIs and influencing factors such as urban form,climate,and population is still unclear,and it is more complicated due to some hidden thresholds.Therefore,how to study the law and degree of influence of each influencing factor on the UHIs from the physical process of UHIs is still a key scientific issue.Therefore,this research aims to explore the law and degree of influence of various influencing factors on the UHIs.Based on the physical process of UHIs,an urban heat island intensity model of the residential district in mid&high-density cities is established.Then conduct a nationwide study on the UHIs,and analyze the impact of the UHIs on the thermal design of buildings.The main contents are as follows:（1）Based on the energy balance principle of the urban underlying surface and the urban canopy,the energy balance equation is solved through the"analytic method"to construct the urban heat island intensity model.The Global Urban Heat Island Data Set（2013）and observation data in China（Xi’an）,the United States（Madison）,the United Kingdom（Birmingham）,and Switzerland（Basel）were used for validation.The verification results show that:the urban underlying surface energy balance calculation module has high calculation accuracy in both suburban and urban areas（suburban:RMSE<1℃;urban:RMSE<3.2℃）;on the daily scale,the calculation accuracy of the urban canopy energy balance calculation module is RMSE<1.5℃,and with lower accuracy on the hourly scale（Xi’an RMSE=4.03℃,Madison RMSE=3.17℃,Basel RMSE=1.94℃）,which has good consistency with the observation data（R²,NSE and IA are all over 0.85）.The observational data is used to verify the rationality of retaining only the first-order term in the construction of the urban heat island intensity model.The verification results show that retaining only the first-order term also has high accuracy（RMSE<0.7℃）.（2）Using the meteorological data,which from the 1019 stations established by the research team and two stations achieved from Energy plus,the contribution analysis of each influencing factor of the UHIs was studied in China.There are obvious seasonal differences in the contribution of various influencing factors to the UHIs.In winter,the contribution of anthropogenic heat and underlying surface heat storage to the UHIs is more significant（both contributions exceed 1.3°C）;in summer,the contribution of vegetation evapotranspiration to the UHIs is more significant（contribution is around1.5°C）;and the contribution of aerodynamic resistance is very significant throughout the year.（3）According to the"Standard of Climatic Regionalization for Architecture"（GB50178-93）,20 typical cities were selected to analyze the impact of vegetation coverage（ρ_v）,building height（h_b）and building density（ρ_b）on the mitigation effect of UHIs.In the climate zone with low relative humidity（Ⅶ）,the contribution of vegetation evapotranspiration is more significantly affected by vegetation coverage.In Turpan,the contribution of vegetation evapotranspiration decreases by 0.33°C for each 10%increase in vegetation coverage.The contribution of the aerodynamic resistance to the UHIs is negatively related to the building height,that is,as the building height increases,the contribution of the aerodynamic resistance gradually decreases;when the building density is low,the change in building height has a relatively insignificant impact（ρ_b=0.2,0.4-2.9℃）,and when the building density is high,the impact is relatively significant（ρ_b=0.7,1.4-8.4℃）.（4）According to the"Code for Thermal Design of Civil Building"（GB 50176-2016）,select typical cities and analyze the impact of UHIs on the thermal design of buildings.The influence of UHIs on thermal isolation is more obvious in Fuzhou and Guangzhou,which are hotter,with the difference of the inner surface temperature of the roof being1.2°C and 1.1°C respectively,and 0.5-0.8°C in other cities;the difference in duration,which the inner surface temperature of the roof exceeds the specified temperature,is 1.9h and 1.5 h respectively,and 0.6-0.8 h for other cities.The laying of external insulation greatly reduces the heat transfer coefficient of the envelope structure,significantly improves the thermal performance,and improves the ability to resist the adverse effects of UHIs.The differences in surface temperature within the envelope structure and in the duration of time out of specification requirements are significantly reduced.The UHIs has a positive impact on the winter thermal insulation design,and the impacts are different under different climatic conditions and different needs.On the whole,in order to meet the needs of anti-condensation,the UHIs has a more significant impact on the minimum thermal resistance.When meeting the anti-condensation requirements,the UHIs has a more significant impact in non-heated rooms.The difference in the minimum thermal resistance between heating and non-heating rooms is 0.01-0.12 m²·K·W^-1 and 0.05-0.52m²·K·W^-1,respectively.