Studies Of Greening’s Effects On Its Thermal Environment

Greening has important effects on the outdoor thermal environment quality and thepedestrian thermal comfort. However, there lack enough systemic studies for a long term,including that how plants affect the thermal environment around them, how to describe andsimulate these effects. In this paper, method of numerical simulation and experimental researchare used to study the influence of the crown on the surrounding environment. Author carried outthe following research.Firstly, a lot of filed experiments were carried out to understand the effects of plant greeningson the thermal environment and the different characteristics among them.Secondly, in order to study the influence of the crowns on the temperature field around trees,the simplified two-dimensional geometric model of canopy and corresponding parameters,i.e., thefractal dimension D, density SVF and leaf area index LAI, are used iced simulation andexperimental measurement, and the effects of the canopy morphological structural parameters onthe temperature field behind the tree are discussed. Through regression analysis with the results ofnumerical simulation, the equation of the relation between temperature distribution inside thecrown and the structural parameters is given. The experimental results show that the test dataagree well with the simulation formula, besides the leaf area index is extreme large, betterconsistency in the changing trends. The temperature around the canopy increases with increasingleaf area index, and decreases with the increase of the wind speed.Third, carried out a common outdoor thermal environment simulation system, it is thecombination of general radiation calculation system, three-dimensional plant canopy flowsimulation method, heat balance of plant canopy and surface, building thermal calculation method,etc. And simulated the outdoor temperature field and flow field of two models, in one model the building is surrender by trees, and the other is only have the building. Then the simulation resultsare compared and analyzed to verify the impact of greening plants on the building flow field andthermal environments.The work of this thesis lays a foundation of accurate prediction and comprehensiveevaluation of the outdoor thermal environment, and lets it possible to guide greening planning anddesign by simulation to improve the outdoor thermal environment.