The paper presents the results of a thermal comfort analysis which was carried out in order to investigate the parameters that influence thermal comfort conditions in urban canyon environment. A ...special computational tool was used for the parametric analysis, so that the degree of influence of each parameter could be examined. Also, a thermal comfort analysis was carried out in order to compare conditions in streets in two different sites, a traditional and a contemporary settlement, using input data from experimental measurements carried out in the two sites. The results are compared to shading simulations and thermal analysis results, as well as to experimental measurements results which have been carried out in urban canyons in the two sites.
► We perform a parametric analysis to investigate thermal comfort in urban canyons. ► We investigate the effect of different parameters on thermal comfort outdoors. ► We investigate the differences between a traditional and a contemporary site.
Aim: Climatic conditions exert a strong control on the geographic distribution of many woodland-to-grassland transition zones (or 'tree lines'). Because woody plants have, in general, a weaker cold ...tolerance than herbaceous vegetation, their altitudinal or latitudinal limits are strongly controlled by cold sensitivity. While temperature controls on the dynamics of woodland–grassland ecotones are relatively well established, the ability of woody plants to modify their microclimate and to create habitat for seedling establishment and growth may involve a variety of processes that are still not completely understood. Here we investigate feedbacks between vegetation and microclimatic conditions in the proximity to woodland–grassland ecotones. Location: We concentrate on arctic and alpine tree lines, the transition between mangrove forests and salt marshes in coastal ecosystems, and the shift from shrubland to grassland along temperature gradients in arid landscapes. Methods: We review the major abiotic and biotic mechanisms underlying the ability of woody plants to alter the nocturnal microclimate by increasing the temperatures they are exposed to. Results: We find that in many arctic, alpine, desert and coastal landscapes the presence of trees or shrubs causes nocturnal warming thereby favouring the establishment and survival of woody plants. Main conclusion: Because of this feedback, trees and shrubs may establish in areas that would be otherwise unsuitable for their survival. Thus, in grassland–woodland transition zones both vegetation covers may be (alternative) stable states of the landscape, thereby affecting the way tree lines may migrate in response to regional and global climate change.
Life quality in urban contexts is related to several interconnected factors. Lots of innovative technologies allow for the gathering of real-time information, which is helpful for analysing and ...interpreting significant urban dynamics and citizens’ behaviours. The presence of people in outdoor environments, particularly for social and recreational purposes, can be considered as a qualitative indicator, giving evidence of a living environment. The relationship between urban areas and the climate context has been addressed in recent years by the scientific literature. However, these studies did not report the direct correlation between people’s presence and outdoor thermal comfort in outdoor spaces. The aim of this paper is to assess whether the presence of people in outdoor public spaces, detected through human presence sensors, can be associated with outdoor microclimatic conditions (both with on-site measurement and software simulation) and outdoor thermal comfort indicators (as physiological equivalent temperature). The question is whether there exists a direct correlation between outdoor microclimate in public spaces and people’s presence, and if a public event plays a role in changing it. The research compares on-site measurements of physics variables (e.g., air temperature) and people’s presence with outdoor microclimate maps by Envi-met. The case study, carried out in the framework of the H2020 project ROCK—Regeneration and Optimization of Cultural Heritage in Creative and Knowledge cities, focuses on two squares located in Bologna’s historic city center. The conclusions show that public events are the main deciding factor influencing square crowding; nevertheless, the study reveals a relationship between thermal comfort and the number of people.
According to the challenge of global warming, trees play an effective role in reducing heat islands and improving thermal comfort. In this study, the impact of urban greening on microclimate and ...pedestrian comfort is studied using ENVI met v4 for a residential district in Tabriz, Iran. In-situ measurements of air temperature and relative humidity have been preliminary performed on ten points in the studied site and collected data used to successfully validate the model. Four scenarios with different trees species and patterns were simulated during typical summer and winter days, to assess benefits and disadvantages during different seasons, in terms of air temperature (Ta) and relative humidity (RH), mean radiant temperature (Tmrt) and physiologically equivalent temperature (PET). Result showed that the best scenario provides great summer cooling without compromising winter comfort. In summer Ta and Tmrt are decreased by respectively 0.29 °C and 20.04 °C; while in winter, they reach respectively 6.92 °C and 13.22 °C, compared the reference scenario characterised by 6.28 °C (Ta) and 23.47 °C (Tmrt). These results in a summer PET improvement from 34.92 °C to 26.16 °C, thus moving from an original hot thermal sensation to a slightly warm one. Based on the outcomes of the study, it is possible to provide useful design recommendation for urban adaptation plans.
•Four scenarios with different trees species and patterns were simulated during typical summer and winter days.•From a qualitative point of view, trends highlight a good agreement among observed and predicted data.•Urban greening design can reduce mean radiant temperatures by 20.04 °C.•The change of RH both in summer and winter is modest and can be considered irrelevant for environmental comfort.
This paper provides an updated literature review about greenhouse systems and helps to identify the most preferable characteristics of a greenhouse for diverse climates and operating conditions. Data ...on appropriate properties of the covering materials and comparisons of several cladding materials were extensively discussed. The selection process of the greenhouse shape and orientation for different climates is presented, and comparisons between several shapes and orientations are made. This paper also examines the existing thermal models and simulation tools used to optimize the thermal operating conditions of the greenhouse. Furthermore, many recent studies are presented where greenhouses are combined with several systems to provide a favorable microclimate for crops, under extreme, tropical and subtropical climates. Finally, other applications such as greenhouse dryers and seawater greenhouse desalination are also discussed.
The built environment modifies energy budget at its proximity and the main related effect is the so-called Urban Heat Island phenomenon consisting in higher air temperature detected in urban contexts ...with respect to rural surroundings. Many studies focus the attention on the existing correlations between cities morphology and Urban Heat Island intensity. Nevertheless, the urban environment is complex and heterogeneous mining that at a lower scale, distinctive microclimate conditions express intra-urban granularity. The intensity of such phenomenon is most commonly analysed by means of a network of weather stations or remote sensing. The current work proposes to analyse the intra-urban microclimate diversification by means of cluster analysis of environmental data gathered through mobile transects at pedestrian perspective. This methodology is applied to four different typologies of urban context, i.e. mainly open site, packed historical, packed low-rise buildings and packed high-rise buildings, where monitoring campaigns are carried out during both day-time and night-time. The obtained results demonstrate potentials of the method in identifying similar morphological structure on the base of row environmental data. The heterogeneity of the selected contexts demonstrates the replicability of the proposed method while suggests the selection of different number of final clusters as function of the monitored context as further development of the study.
•Urban microclimate monitoring through mobile transects.•Pedestrian perspective captured by means of wearable sensing techniques.•Environmental data mapping in variable intraurban contexts.•Urban pattern described from environmental data clustering (bottom-up process).•Wearable sensing as useful tool for microclimate change analysis.
Camping has become a popular outdoor activity in China. However, the long and scorching summers in China's hot and humid regions pose challenges for campsites in maintaining thermal comfort. ...Therefore, we explored the impact of tree species and planting methods on the thermal comfort of urban campsites in hot and humid areas using the ENVI-met model to simulate the conditions of the study area. The reliability of the model was validated by comparing the simulated values of air temperature (T
) and relative humidity (RH) with field measurements. We conducted an in-depth analysis of common trees in hot and humid areas and analyzed the effects of five tree species and four tree planting forms on the microclimate of campsites in such areas, using the physiological equivalent temperature (PET) as the evaluation index of thermal comfort. The results indicated that: (1) trees with larger crown widths were most effective in improving outdoor thermal comfort. The ability of trees to regulate microclimate was more influenced by crown width than by leaf area index (LAI), and (2) trees planted in patches provided the highest level of thermal comfort, whereas single trees provided the lowest. However, relying solely on tree planting made it difficult to significantly reduce outdoor heat stress. Therefore, other methods such as increasing ventilation or mist spray should be adopted to modify camping area. This study provides a reference for the planting design of outdoor campsites in hot and humid regions of China.
•Cooling is not only a function of vegetation and surface materials, but also dependent on the form and spatial arrangement of urban features.•At the microscale, urban form has a larger impact on ...daytime temperatures than landscaping.•In mid-afternoon, dense urban forms can create local cool islands.•Spatial differences in cooling are strongly related to solar radiation and local shading patterns.•The LCZ classification scheme is a useful concept for integrating local climate knowledge into urban planning and design practices.
This study investigates the impact of urban form and landscaping type on the mid-afternoon microclimate in semi-arid Phoenix, Arizona. The goal is to find effective urban form and design strategies to ameliorate temperatures during the summer months. We simulated near-ground air temperatures for typical residential neighborhoods in Phoenix using the three-dimensional microclimate model ENVI-met. The model was validated using weather observations from the North Desert Village (NDV) landscape experiment, located on the Arizona State University's Polytechnic campus. The NDV is an ideal site to determine the model's input parameters, since it is a controlled environment recreating three prevailing residential landscape types in the Phoenix metropolitan area (mesic, oasis, and xeric). After validation, we designed five neighborhoods with different urban forms that represent a realistic cross-section of typical residential neighborhoods in Phoenix. The scenarios follow the Local Climate Zone (LCZ) classification scheme after Stewart and Oke. We then combined the neighborhoods with three landscape designs and, using ENVI-met, simulated microclimate conditions for these neighborhoods for a typical summer day. Results were analyzed in terms of mid-afternoon air temperature distribution and variation, ventilation, surface temperatures, and shading. Findings show that advection is important for the distribution of within-design temperatures and that spatial differences in cooling are strongly related to solar radiation and local shading patterns. In mid-afternoon, dense urban forms can create local cool islands. Our approach suggests that the LCZ concept is useful for planning and design purposes.
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