Research On Benefit Evaluation Of Urban Heat Island Mitigation Based On Quantitative Simulation Analysis

High energy consumption has resulted in many serious environmental problems such sa air pollution, global warming, urban heat island effect, deterioration of ecological environment etc. Deteriorating urban environment and the growing urban heat island effect have strengthen the people to adhere to the aspirations of sustainable development, strengthen the search for a rational and efficient urban heat island mitigation strategy needs. This dissertation aims to summed up the urban heat island mitigation techniques and the quantitative simulation methods of urban heat island mitigation based on analyzing the current situation of urban development at home and abroad, and evolution of heat island. The urban heat island mitigation benefit evaluation system was founded on this basis, to set up the relationship between the urban heat island mitigation strategies and its effectiveness, to provide the guidance and reference to the urban heat island mitigation, urban heat environment improvement, urban energy conservation, urban planning and management and other related areas to some extent, and to provide a scientific basis and technical guidance to the environmental improvements for human living, life, work, recreation and so on.Firstly, the dissertation described the mechanism of urban heat island, including the changes of urban land use, reduction of natural land surface, urban anthropogenic heat emissions, etc.; which launched the urban heat island mitigation strategies; also summed up the heat island mitigation technologies, which is relatively widespread use of, including trees and vegetation, green roofs, cool roofs, pavement cooling, etc.Secondly, based on the analysis of the urban heat island formation mechanism and the urban heat island mitigation strategies, the quantitative simulation of urban heat island mitigation on different scales was studied, including urban scale and block scale. The results indicate that the urban heat island mitigation the main man-made controllable factors on the urban scale includes vegetation index(NDVI), surface albedo, building density, floor area ratio and building height, whose relevance order was:NDVI> albedo> building density> building height> floor area ratio; and three-dimensional distribution of thermal environment on block scale is affected by surface material, the ratio of building distance and height, construction enclosure, etc.; especially in the vertical direction, the main factors and distribution of the temperature change as the story is different.Thirdly, on the basis of quantitative simulation of the urban heat island mitigation, benefit evaluation factors of the urban heat island mitigation were selected on different scales, including economic evaluation factors (energy savings, cost savings, etc.) and social evaluation factors (human comfort, work efficiency, health standards, disaster frequency, etc.). Analytic Hierarchy Process (AHP) was used to comparative analysis economic benefits and social benefits under different heat island mitigation strategies on different scales.Finally, a certain range in west of Hangzhou city (221.16km2) on summer was selected as a case study. The results show that different heat island mitigation measures by not changing the volume within the study floor area ratio, increasing the vegetation within the study area index (0.01), surface albedo (0.05), the average building height (30) and to reduce the building density (-6); or not changing the surface albedo or building density, but increasing the vegetation within the study area index (0.09), the average building height (25) and reduce the floor area ratio (-0.5), and so on, can reach a mitigation benefits of the temperature dropped 1.28℃; energy savings of 3.41×108kJ; electricity demand savings of 16.81×104kwh and cost savings of 12,563,900 RMB.The dissertation concluded that the major controllable man-made factors of the urban heat island mitigation, like the vegetation index, surface albedo, floor area ratio, etc. can be changed in order to mitigate the urban heat island effort, which can generate considerable economic benefits, achieve "win-win" for the urban ecology and economy, improve the urban thermal environment, provide reasonable mathematical support and scientific basis for the implementation of urban planning and management, and contribute to the energy saving and sustainable development of mankind, in urban planning or construction by quantitative simulation of heat island mitigation and simulation of the benefit evaluation based on the quantitative estimates.