Experimental Analysis of the Influence of Urban Morphological Indices on the Urban Thermal Environment of Zhengzhou, China

Summer extreme high-temperatures occur frequently in large cities; urban spatial form is the primary factor affecting the urban thermal environment. Thus, planning and arranging urban spaces is a key approach to regulating urban microclimates. Studies into how urban spatial forms influence the formation of urban microclimates have been carried out for multiple cities in warm and hot regions; however, few studies of this kind have been carried out for cities in cold regions. In this study, we analyze Zhengzhou, a city located in a cold region of China, using summer 2017 measurement data to determine why high temperatures develop in cold areas. We investigated how temperature and humidity vary during the morning, at noon, and in the evening given different land use properties (commercial and residential) and different spatial forms (building height, building density, green coverage rate, and plot ratio); we then studied the correlation between urban spatial form and the urban thermal environment. Our research results indicate that the commercial district’s thermal microclimate was related to PR and BH in the afternoon and GCR in the morning and at night. In the residential district, the key urban morphology factors related to its thermal microclimates were BD, PR, and GCR during almost the whole day.

Climate maps as instruments for urban planning

There has been a significant increase in studies on climatic mapping linked to urban planning, with the spatialized distribution of urban microclimates, in order to guide municipal actions, aiming at environmental comfort. In this research, various climatic studies have been reviewed so as to develop maps for climate analysis and to draw up recommendations on the use and occupation of land. Climatic classification was adapted for topoclimates, through the overlapping of layers and by attributing heat accumulation values to the base layers. In the city of Recife, fourteen microclimates were identified, categorized into coastal, plain and hillside macrozones. The neighborhoods of Boa Vista and Soledade presented eight microclimates, synthetized into three classes of heat accumulation, which were predominantly high, chiefly in areas of densification, and verticalization. The recommendations aim to assist in urban management, so as to act more precisely in the critical areas, and thereby, as a result of reviewing the urban parameters, provide guidelines for more effective projects on both urban and architectural scales.

A seasonal assessment of urban outdoor thermal exposure in a humid continental climate using the MaRTy observational platform

<p>Many cities in the northern hemisphere experience both extreme heat and extreme cold weather. Pedestrians are exposed to these thermal extremes, causing bodily stress. With a growing and ageing urban population, city design that contributes to the mitigation of summer heat exposure while also reducing winter cold exposure is of increasing importance. Pedestrian thermal exposure depends on several microclimatic factors in addition to air temperature, including wind speed, humidity, as well as shortwave and longwave radiation, which can be quantified by the mean radiant temperature (<em>Tmrt</em>). There has been little study of the impacts on pedestrian thermal exposure in climates with high humidity during summer and snow cover in the winter. We gathered seasonal radiation data from varied urban microclimates using the six-directional <em>Tmrt</em> method in a Canadian city. We deployed a mobile human-biometeorological weather station (<em>MaRTy cart</em>), which has previously been used primarily in hot, dry climates. <em>Tmrt</em> profiles are decomposed into their directional components, and they demonstrate substantial differences in the drivers of thermal exposure between seasons and locations within the city.</p>

Differences in the Influence of Microclimate on Pedestrian Volume According to Land-Use

Identifying how the urban environment affects pedestrian volume is a traditional urban planning topic. Recently, because of climate change and air pollution, interest in the effects of urban microclimates has been increasing. However, it is unclear whether the effects of microclimate on pedestrian volume can vary depending on the urban environment. This study determines whether microclimate’s influence on pedestrian volume differs according to land-use in the urban environment in Seoul, Korea. We constructed eight models with microclimate factors (temperature, precipitation, and PM10) as independent variables, using pedestrian volume as the dependent variable. We classified the models according to season and land-use and conducted a negative binomial regression analysis. The results confirmed that the effect of microclimate on pedestrian volume varies by land-use. A summary of the results is as follows. First, residential areas had more microclimate factors that significantly affected pedestrian volume compared to commercial areas. Second, for microclimate variables that had significant influences in commercial areas, the size of their influence was greater in commercial than in residential areas. Third, the influence of microclimatic factors on pedestrian volume in mixed-use areas has intermediate characteristics between residential and commercial areas.

Using ENVI-met simulation to analyze heat island intensity in megalopolises

Introduction. The simulation of urban microclimates, including the urban heat island (UHI) phenomenon, has turned all the more important for urban planning. Presently, the analysis of this phenomenon is feasible thanks to high computational power of computers and links between computer modeling instruments and databases that contain information on urban environments. Advanced hardware helps to study characteristics of urban microclimates by analyzing and assessing their exposure to various climatic and anthropogenic urban factors (urban morphology, land use, construction sites, albedo, etc.) Materials and methods. ENVI-met is a software model used to simulate microclimates in urban environments. This software can optimize proportions of buildings and streets, outdoor shading, outdoor space planning, air movement, and use of construction materials in respect of thermal comfort and measures taken to mitigate consequences of urban heat islands within the framework of environmental planning of new districts. The co-authors analyze Ha Dong, a Hanoi district characterized by the high density of high-rise buildings. The co-authors consider the example of this district to study the process of detailed simulation, analysis and assessment of UHI effects. Results. ENVI-met and its simulation capacity is employed to prove that the air temperature in Wang Fu, an urban area, gradually rises from 8 am to 5 pm, when the air temperature reaches its maximal value of 32.28 °C during the period of sixteen hours. UHI intensity was maximal between midnight and 1 am on May 29, 2017, when it reached 2.41 °C. Conclusions. Cities are complex systems exposed to a wide array of interactive factors that influence the urban climate change. The value of R2 equal to 0.94 has proven the reliability of ENVI-met applied to simulate and imitate the climate of Hanoi, which is a hot and damp tropical city.

Packaging Environmental Sensors for Monitoring Urban-Microclimates

An internet-of-things (IoT)-based low-cost sensor network can be used to collect the data necessary to study both Urban Heat Island (UHI) and air pollution. There are several key challenges associated with an IoT-based solution to environmental data monitoring, including packaging and deployment. This study explores these challenges by looking at effects the packaging has on the deployed environmental sensors. Several packaging designs are numerically studied using a computation fluid dynamics (CFD) model. Two sensor designs are chosen using results obtained from CFD modeling and then experimentally deployed. The findings conclude that the IoT sensors chosen for this study are not significantly affected by flow velocities or require advanced packaging designs when paired with street-side outdoor digital displays.

A Microclimate Study of Traffic and Pedestrianization Scenarios in a Densely Populated Urban City

Urban streets are known to have a significant role in creating urban microclimates. This study aims to empirically quantify temporal and spatial microclimate variation within the same street configurations with pedestrian schemes. To evaluate the urban microclimates at the pedestrian level, a detailed monitoring project was performed at five representative locations near intersections, within a busy street canyon of the typical urban community in a densely populated urban city. Monitoring was done for warm and cool seasons. A strong, significant correlation (p<0.01) was found under multiple time scenarios (traffic, nontraffic, and as a whole) and for both seasons. These findings suggest that the average urban daily temperature was not significantly reduced when there was no vehicular traffic present, whereas pedestrian activity contributed to urban heat regardless of the season. These findings provide an essential foundation for further studies on urban microclimates within pedestrianized areas and will likely lead to better urban design and policy management, especially concerning thermal comfort and Quality of Life at the pedestrian level.