三坊七巷小黄楼庭院空间的气候适应性模拟

为探究植被对人体舒适度的影响及庭院在极端季的微气候环境,文章以福州古典园林典型庭院小黄楼东花厅为研究对象,运用ENVI-met建立实际模拟和仅乔木模拟两种方案进行对比研究,并对实际方案进行量化模拟研究。结果表明:1)当乔木覆盖率达40%时,从时间和空间维度,两种方案的PMV值拟合度均较高,此时乔木对人体舒适度有强烈影响;2)夏季9∶00-17∶00,冬季9∶00前、17∶00后游人不宜长时间在室外活动,应适当调整小黄楼这类庭院的开放时间,如延长夏季开放时间;3)应加大对传统庭院与建筑的宣传保护力度,适当开展戏曲、灯展等文教活动,弘扬传统文化;或将庭院景观与灯景结合,提升景观观赏价值。     

南京市寒冷季节景观树种对人体热舒适度影响的数值模拟研究

开展景观植物对人体热舒适度影响的研究对于优化景观设计和园林绿化植物配置具有一定的理论指导意义。在验证ENVI-met模拟精度的基础上，以南京市寒冷季节为气候背景，选取南京市6个不同规格常绿及落叶乔木、灌木树种进行微气候效应模拟，通过Rayman平台计算其热舒适PET值，分析与空地对照组的差异性及影响规律。结果表明，寒冷季节植物对PET有不同程度提升作用。其中乔木对PET影响白天强于夜间，常绿小乔木强于其他乔木，但乔木对PET的影响整体上不显著。寒冷季节灌木对PET影响强于乔木，整体上白天强于夜间，常绿灌木强于落叶灌木。常绿灌木对PET的影响程度与灌木高度呈负相关，与叶面积密度（LAD）和郁闭度呈正相关。     

Effects of vegetation,urban density,building height,and atmospheric conditions on local temperatures and thermal comfort

This paper shows the effects of several variables, which co-cause the Urban Heat Island effect on temperature distribution and outdoor thermal comfort (by using the Predicted Mean Vote, PMV) on dense urban environments. The study was conducted by means of a three-dimensional microclimate model, ENVI-met 3.1, which forecasts the microclimatic changes within urban environments. The effects of building density (% of built area) and canyon effect (building height) on potential temperature, mean radiant temperature, and Predicted Mean Vote distribution are quantified. The influence of several types of green areas (vegetation on the ground and on roofs) on temperature mitigation and on comfort improvements is investigated for different atmospheric conditions and latitudes in a Mediterranean climate. The research quantifies the effects of the variables investigated on temperature distributions and in determining outdoor comfort conditions. Vegetation on the ground and on roofs mitigates summer temperatures, decreases the indoor cooling load demand, and improves outdoor comfort. The results of the study demonstrate that density and height of buildings in a city area influence potential temperature, mean radiant temperature, and Predicted Mean Vote distribution; for most of the cases examined higher density causes higher temperatures and with taller buildings vegetation has higher cooling effects. Considering the cooling effect of vegetation, a difference can be noticed depending on the amount of green areas and vegetation type. The results of this study show also that vegetation is more effective with higher temperatures and lower relative humidity values in mitigating potential temperatures, mean radiant temperatures, and PMV and in decreasing the cooling load demand.     

基于ENVI-met的道路绿带植物配植对PM2.5浓度影响模拟

为改善城市道路人行空间的空气质量,以杭州市临安区武肃街为研究对象,将道路分车绿带和行道树绿带两两组合,构成乔灌-乔草(Ⅰ)、乔灌-乔灌(Ⅱ)、灌草-乔草(Ⅲ)和灌草-乔灌(Ⅳ)4种配植方式,并以无植物种植的道路为参照(CK),采用实地监测与ENVI-met软件模拟相结合的方法,探究道路绿带内不同植物配植方式对PM2.5浓度的影响。结果表明,实测PM2.5浓度日变化(8:00-16:00)表现为上午和下午较高、中午低的趋势;人行道的PM2.5浓度实测值与模拟值呈极显著正相关(P <0.01,R~2=0.944)。模拟显示,CK的PM2.5浓度最高值出现在机动车道处,PM2.5随风向向外扩散;相较于CK,在垂直方向上,非机动车道和人行道处Ⅰ和Ⅱ的PM2.5扩散高度均低于Ⅲ和Ⅳ的,且人行道处Ⅲ和Ⅳ在4~6 m高度处均有PM2.5聚集现象;在水平方向上,非机动车道处4种配植方式的PM2.5消减率均下降,人行道处Ⅰ和Ⅱ的消减率分别增加1.94%和0.87%,而Ⅲ和Ⅳ的消减率分别减少0.51%和0.89%。乔灌型分车绿带和乔草型行道树绿带是道路绿带的最佳植物配植方式。     

Effects of green roofs’ variations on the regional thermal environment using measurements and simulations in Chongqing,China

In the present work, field measurement and simulation method were employed to investigate the effects of several green roofs variables on regional thermal environment in Chongqing (29°N, 106°E), China. Field experiments were conducted in two typical places. The real influence of green roofs on ambient environment was analyzed and compared with the simulation results. The software ENVI-met was employed to simulate 29 cases with different factors, including green roofs types, vegetation coverage, building height, arrangement position and regional layouts. With the aim to investigate the effect of the green roofs thoroughly, different design factors of green roofs were taken in consideration. From the aspect of cooling effect, it can be found that enclosing layout has the maximum air temperature drop, which is up to 0.5 °C. From the perspective of the uniformity of regional environmental temperature distribution, the regional thermal environment of scattered layout is better than enclosing and array layout as a whole. In addition, with the same vegetation coverage, the effectiveness of air temperature dropping of the whole region differed according to the arrangement position. Centrally arranging the green roofs upwind can effectively reduce the air temperature of the whole region. These findings can be used to improve the regional thermal environment by designing the green roofs reasonably.     

Using green infrastructure for urban climate-proofing: An evaluation of heat mitigation measures at the micro-scale

Urban green infrastructure (UGI) has been increasingly promoted as a key measure to mitigate heat stress in cities caused by the urban heat island effect and climate change impacts, including climate variability and extremes. However, comparable information concerning the performance of different UGI types to moderate such impacts is mostly lacking. This creates serious challenges for urban planners who need to decide on the most effective measures while considering spatial and administrative constraints. This study investigates how different types and quantities of UGI, i.e. trees, green roofs, and green facades, affect pedestrian thermal comfort. The study was applied to high-density residential areas under current and future climatic conditions. Climate change will on average increase afternoon Physiological Equivalent Temperature (PET) values by 2.4 K; however, this could be vastly reduced by different UGI scenarios. Planting trees had the strongest impact with an average PET reduction of 13% compared with existing vegetation. Trees shade open spaces and provide evapotranspirative cooling. Another valuable adaptation option is green facades, which have mitigating effects of 5%–10%. In contrast, the effects of green roofs were negligible. Our results indicate that increasing the share of green cover did not directly correspond to the magnitude of the PET reduction. Placing vegetation strategically in heat-exposed areas is more effective than just aiming at a high percentage of green cover. We conclude that our extensive comparative analysis provides empirical evidence to support UGI on the micro-scale and assists planners and decision-makers to effectively select and prioritise concrete measures to adapt to climate change.     

Enhancing the thermal comfort on urban level in a desert area: Case study of Dubai,United Arab Emirates

The urbanisation of deserts in Dubai is one way in which this city can expand and explore its full potential. In this piece of research, a case study of the Dubai International Academic City was used as a basis from which to study the importance of planning and orientation of projects in open, unpopulated land. It demonstrates the various alternatives for project orientation relative to the sun and wind, its effects on temperature and wind readings and consequently on outdoor thermal comfort levels. ENVI-met was used to simulate various scenarios generated from the existing base case in both summer and winter. The orientation which best promoted and allowed for higher wind flow through the project was found to record the best outdoor predicted mean vote levels, approaching a neutral state. The findings of this research may be used for setting up regulations regarding the planning of desert areas in Dubai on the basis of early assessment of designs.     

道路植被结构对大气可吸入颗粒物扩散影响的模拟与验证

为了研究道路植被结构对城市内可吸入颗粒物（简称PM10）扩散的影响,该文设计不同道路绿化布局模式,在夏季和冬季不同的风向条件下,利用三维微气候模型（ENVI-met模型）模拟大气颗粒物扩散的规律;另外,该文选择百子湾路、林大北路、交道口东大街、东直门北小街、农展馆南路6条不同绿化布局的道路作为北京市街区道路的典型案例,监测夏季和冬季不同绿化布局道路的可吸入颗粒物浓度,并与ENVI-met模型模拟结果进行对比。结果表明：在高宽比一定的情况下,乔灌草的布局方式对PM10浓度降低作用最明显,其次是乔灌组合方式,乔木对降低PM10浓度的作用较弱,灌木对降低PM10浓度的作用最弱;在植被布局相同的情况下,街道高宽比值越小,PM10浓度降低的越明显。实测和模拟结果对比发现：两者相对误差分布在10%以下的占全部的71%,相对误差分布在10%至20%占全部的22%,相对误差分布在20%以上的仅占全部的7%;模拟值和实测值拟合的决定系数R2为0.9894,RMSE为8.399 μg/m3,说明模拟结果精度较高,因此ENVI-met模型能够合理模拟道路植被结构对大气颗粒物扩散的影响,对PM10浓度降低作用角度考虑乔灌草的布局方式最优。     

不同绿化改造方案对小区微气候环境影响的ENVI-met模拟研究

【目的】利用数值模拟不同绿化布局方案对居住区微气候的影响,以期获取最优绿化方案。【方法】以广州某老旧小区为研究对象,选取典型湿热天气条件,对研究区的室外微气候要素进行测量;利用模拟软件ENVI-met构建实况数值模拟模型,将模拟结果与实测值进行对比分析,验证模型精度和质量;对研究区预设的3种绿化方案微气候特征进行模拟分析。【结果】清理灌木后温度较现状平均升高0.1℃,湿度平均降低0.51%,可适当改善低处通风情况;去除乔木后温度升高近0.4℃,湿度降低1.18%,整体风速明显增大;屋顶简单式绿化具有一定的降温增湿效果,温度降低0.16℃,湿度增加1.17%,风速较现有绿况变化不大。【结论】ENVI-met能够较好地预测温度和湿度的日变化趋势,能有效地评估老旧小区空间的营造与绿化改善效果。     

The influence of spatial configuration of green areas on microclimate and thermal comfort

It has been shown that the spatial configuration of a green area can strongly influence its cooling effect. However, the specific correlation has not been sufficiently studied. To systematically clarify the correlation between the spatial configuration and the cooling effect of green areas, 25 idealized scenarios are designed and simulated using the microclimate model ENVI-met. These 25 scenarios represent green areas with five different spatial configurations (integrated green area, sparse dotted green areas, dense dotted green areas, belt-shaped green areas parallel to wind direction, and belt-shaped green areas vertical to wind direction) and five vegetation types (trees with big canopies, trees with small canopies, hedges and shrubs, 50 cm grass, and 10 cm grass). The human thermal comfort of each scenario is evaluated by means of physiologically equivalent temperature (PET) using Rayman. The results reveal the influence of the fragmentation degree (quantified by the patch density and edge density), shape complexity (quantified by the land shape index), orientation of green belt, and vegetation type on the cooling effect of a green area. The spatial configuration and the vegetation type of green areas were found jointly affecting the efficiency of the green areas’ cooling effect. The highest cooling effect appears at 2 pm, reaching 6.3 K in the scenario of belt-shaped green areas parallel to the wind direction and with big canopy trees. The conclusions of this paper can provide suggestions for the climate-adaptive design and planning of urban green areas in the future.