The Characteristic Of Landscape Microclimate In Campus And Its Optimizing Strategy

The increasing global climate change has posed a severe challenge to human living environment in city.As the tool that coordinate the relationship between human and nature,landscape architecture plays a vital role in climate change mitigation and adaptation.The microclimate in small range is closely related to our daily life.How to optimize microclimate and improve life quality in urban city with the help of the design idea of landscape architecture has become the common focus of scholars and designers.Campus is the most important place for teachers and students to live,study and communicate.Favorable campus environment could improve the level of education and the efficiency of learning.Taking Weigang Campus of Nanjing Agricultural University as research subject,the paper used HOBO Onset recorder to collect temperature and humidity data of 21 sample plots from October 14th,2017 to February 28th,2019 on campus and explored the characteristic,differences and its impact factors of microclimate.Then applying ENVI-met to analyze the campus thermal environment and discussing the impact of climate type,surrounding environment,layout form and canopy shape on the regulation of microclimate.Finally,putting up targeting optimizing strategy of microclimate according to the structure of the paper.The main conclusions are as follows:1)The field measurement shows that there are great differences between each sample plot.Specifically,there are significant differences between the total sum of temperature and humidity in the whole year of all the sample plots.The highest total sum of temperature is 6584.52?,the lowest is 6206.68?,and the average is 6372.87±37.86?.The highest total sum of humidity is 26374.81%,the lowest is 24989.80%and the average is 25656.80±137.79%.At the same time,the differences between each sample plot is more significant in daytime than nighttime,especially in noon and afternoon.At each season,the differences between the temperature of each sample plot is smaller in spring and summer while higher in autumn and winter.The differences between the humidity of each sample plot is smaller in summer and autumn while higher in spring and winter.2)The plants and buildings have marked impact on the cooling and humidification effect of microclimate Specifically,the two-dimension green biomass has positive correlation with the average daytime cooling and humidification efficiency in spring,summer and autumn(p<0.05);the building height has negative correlation with the average daytime cooling efficiency in spring and autumn(p<0.05).While in the night,plants and building have nearly zero impact on cooling and humidification efficiency.Comparing to the building height,the two-dimension green biomass may has more significant impact on cooling and humidification efficiency.The comprehensive influence of plants and buildings on the cooling and humidification efficiency perform differently in different seasons and different time.Specifically,it's mainly has significant impact on the daytime and nighttime average cooling and humidification efficiency in autumn and winter,as well as the daily average cooling and humidification efficiency in spring,summer and autumn.3)The simulation of campus shows that ENVI-met has higher accuracy when simulating the microclimate on summer solstice than winter solstice.The possible reason are ENVI-met 4.0 doesn't have enough plant models,especially lack evergreen plants.While there are many evergreen plants on campus,the simulation results and field measurement may have larger differences because of that.4)Based on the ENVI-met simulation of campus,The thermal environment of campus in summer is comfortable and the daily average of PMV is 1.49±0.33.The shading of buildings and trees are the main reasons of comfortable thermal environment.The uncomfortable areas are parking lots,playing ground and the partial areas between dormitory buildings,where the PMV is over 4.5)Based on the ENVI-met simulation of virtual environment,the surrounding environment,layout form and canopy shape have significant impact on the cooling and humidification effect of microclimate,which performs variously in different climate type.When proceeding the optimizing of microclimate,the first thing is to consider the local climate and realize the microclimate problems that need to be solved.Then taking a survey about the surrounding environment of the specific site and the primary type of activities of people.Last but not the least,choosing the appropriate plants and planting form to create comfortable microclimate.