Assessing outdoor thermal comfort in high-density urban Kampungs in Tamansari, Bundung: a microclimate simulation study

At present, the environmental quality of urban regions and outdoor spaces has turn out to be one of the main issues facing both climatologists and designers, which could be identified through their research outcomes. It is argued that the urban configuration affects the micro-climate of the urban outdoor spaces. The street’s orientation form was identified as an element, which impacts the urban environment with regards of receiving passive solar, solar radiation and reflection against urban absorption, wind flow and the possible urban cooling techniques. The key purpose of this study is to look into the urban configuration factors affecting the human thermal outdoor comfort in Jeddah city as an example of hot humid climate regions. To accomplish its aim, the research is divided to two sections. The first one illustrates the problem of the research, then generally reviews the literature associated with the outdoor human thermal comfort; in addition, it discusses the relationship between street orientation and micro-climate. The second section highlight the assessments carried out between four different orientations of urban streets from two different districts in Jeddah city, using ENVI-met software. The research adopts three environmental variables to be examined, namely air temperature, wind speed, relative humidity together with pedestrian thermal comfort as indicators for predicted mean vote, during summer and winter seasons. The outcomes of the comparison assist to identify decisions related street networks to achieve the desirable human outdoor thermal comfort in such an urban environment.

In recent years, the city of Mumbai has been experiencing the pressing challenge of urban heat islands, affecting the thermal comfort of its high-density urban environment, impacting both air and surface temperatures. The Intergovernmental Panel on Climate Change (IPCC) projected that climate change would adversely affect 27 million people in Mumbai (6th assessment report). Understanding the intricate relationship between the built environment and its influence on microclimates and thermal comfort was imperative for creating climate-sensitive designs. This paper investigated the role of urban morphology in improving the thermal comfort of a typical neighborhood in Mumbai. The analysis was based on simulations conducted using ENVI-met, a 3D urban climate modeling tool. The research aimed to comprehend how open spaces, aspect ratio, setbacks, and plot boundary conditions within the neighborhood affected outdoor thermal comfort. The objective was to underscore the significance of urban designers and planners in assessing the impact of built environments on microclimates and leveraging microclimatic insights for the design of public spaces. Air temperature, relative humidity, wind speed, and mean radiant temperature were measured at 15 locations within the neighborhood, Matunga east, and its primary street in February 2023. The recorded data were used to validate the Envi-Met model . Two distinct scales were analyzed: neighborhood-level and plot-level iterations. Neighborhood-level iterations focused on block-level modifications, while plot-level iterations examined street and boundary conditions. Each iteration was evaluated using EnviMet to assess changes in thermal conditions relative to the current site conditions (Base case). The analyses were conducted for the critical summer month (May). The study ultimately revealed that the introduction of road networks in prevailing wind directions and the incorporation of green open spaces within the urban fabric could reduce overall heat stress duration from 12 hours to 6 hours. Smaller-scale interventions, such as 50% porous pavements and strategically placed trees, also yielded positive outcomes. This research aspired to provide urban planners with a comprehensive framework that integrated outdoor thermal comfort as a pivotal aspect in the design of future urban landscapes.

A quantitative evaluation model of outdoor dynamic thermal comfort and adaptation: A year-long longitudinal field study

As a main place for student activities on campus, outdoor spaces have positive impacts on students’ physical and mental health. Namely, outdoor heat and comfort are of great significance to improve activity quality. Here, four unique outdoor spaces were studied to explore the varying effects on human thermal comfort during hot-summer and cold-winter periods. Distinct outdoor spaces (fully open, semi-open, semi-enclosed, and fully enclosed areas) from the southern campus of Anhui Jianzhu University were chosen. The PET was used as a metric for measuring thermal comfort and analyzing correlated spatiotemporal distributions. The results showed that outdoor thermal comfort was derived from multiple factors, including vegetation, underlying surface materials, building presence, and wind-heat environment. Notably, high correlations between Tmrt and thermal comfort were revealed, where such temperatures of places with trees or building shade were low; thus, PET was low. Further, Ws showed a significantly negative correlation with PET. Of the four outdoor space forms, the fully enclosed location had the lowest thermal comfort level, while the semi-enclosed spaces showed the highest level of body comfort. Therefore, semi-enclosed space (U-shaped) is recommended in campus planning and construction. Accordingly, an improved strategy was proposed based on experimental transformation for fully enclosed spaces. The thermal comfort after optimization was simulated to provide references for outdoor space thermal comfort improvement during seasonal extremes.

PurposeComfortable outdoor workspaces are important for employees in business parks and urban areas. Prioritizing a pleasant thermal environment is essential for employee productivity, as well as the improvement of outdoor spaces between office buildings to enhance social activities and quality of outdoor workplaces in a hot arid climate has been subjected to very little studies Thus, this study focuses on business parks (BPs) landscape elements. The objective of this study is to enhance the user's thermal comfort in the work environment, especially in the outdoors attached to the administrative and office buildings such as the BPs.Design/methodology/approachThis research follows Four-phases methodology. Phase 1 is the investigation of the literature review including the Concept and consideration of BP urban planning, Achieving outdoor thermal comfort (OTC) and shading elements analysis. Phase 2 is the case study initial analysis targeting for prioritizing zones for shading involves three main methods: social assessment, geometrical assessment and environmental assessment. Phase 3 entails selecting shading elements that are suitable for the zones requiring shading parametrize the selected shading elements. Phase 4 focuses on the optimization of OTC through shading arrangements for the prioritized zones.FindingsShading design is a multidimensional process that requires consideration of various factors, including social aspects, environmental impact and structural integrity. Shading elements in urban areas play a crucial role in mitigating heat stress by effectively shielding surfaces from solar radiation. The integration of parametric design and computational optimization techniques enhances the shading design process by generating a wide range of alternative solutions.Research limitations/implicationsWhile conducting this research, it is important to acknowledge certain limitations that may affect the generalizability and scope of the findings. One significant limitation lies in the use of the shade audit method as a tool to prioritize zones for shading. Although the shade audit approach offers practical benefits for designers compared to using questionnaires, it may have its own inherent biases or may not capture the full complexity of human preferences and needs.Originality/valueFew studies have focused on optimizing the type and location of devices that shade outdoor spaces. As a result, there is no consensus on the workflow that should regulate the design of outdoor shading installations in terms of microclimate and human thermal comfort, therefore testing parametric shading scenarios for open spaces between office buildings to increase the benefit of the outer environment is very important. The study synthesizes OTC strategies by filling the research gap through the implementation of a proper workflow that utilizes parametric thermal comfort.

Intensified human population encourages urbanization changing the morphology and metabolism of urban environments, thus altering the local climate and outdoor thermal comfort (OTC) in public spaces. OTC is an increasingly urgent area of research for tropical climates. This study explores the literature from the Scopus database on urban microclimate and OTC in public spaces and contrasts the studies in warm-humid cities through a bibliometric mapping of literature. The adapted methodology includes; Bibliometric Search, Scientometric Analysis, and Content analysis using VOSviewer software to identify the evolution paths, gaps, and the most recent movement of OTC assessments in urban public spaces. Results reveal five evolution paths related to all climatic regions; 1) materials and cooling strategies, 2) simulation modeling and urban planning, 3) design parameters affecting thermal perception, 4) cooling effects of green infrastructure, and 5) thermal adaptation in urban design. Although urban morphology and vegetation have been received the highest attention respectively, only a few for blue infrastructure related to warm-humid cities. This review identified five research gaps; the impact of blue infrastructure on OTC, strategies to overcome the effect of reflective materials, vegetation configurations in street canyons with wind flow, OTC improvements in asymmetrical street canyons, and how local climate zone (LCZ) classification approach could be used for OTC assessments. Past empirical studies have revealed that urban vegetation, surface materials, and morphological parameters are of paramount importance. Yet, the urban blue infrastructure has not received adequate research. Recently, the attention of researchers has been drawn to strategies in improving OTC using micro-meteorological simulation modelling to examine the impact of urban design interventions. Finally, comprehensive content analysis, bibliographic coupling based on documents, co-occurrence of all-keywords, are suggested for future bibliometric reviews. Finally, further research on recommended areas would assist decision-makers in planning and design to enhance livability by improving microclimate and OTC in urban spaces.

Studies of thermal comfort and space use in an urban park square in cool and cold seasons in Shanghai

Outdoor thermal comfort improvements due to innovative solar awning solutions: An experimental campaign

Numerical modelling of mean radiant temperature in high-density sub-tropical urban environment

Outdoor thermal comfort and adaptation in severe cold area: A longitudinal survey in Harbin, China

Thermally comfortable urban squares attract people and provide various social benefits to the urbanites. Compared to urban parks, squares are more vulnerable to thermal discomfort due to surrounding buildings and the high percentage of hard surface coverage, especially in tropical climates. The spatial arrangement of green infrastructures can improve Outdoor Thermal Comfort (OTC) by reducing hot air flows, evapotranspiration, and shading to reduce the negative effect of warming urban environments. However, it is not yet adequately discovered the specific correlation of different vegetation arrangements on OTC. Still, urban policymakers are looking for new, quantitative methods to assess the performance of their designs in terms of the cooling effects provided by vegetation. Therefore, the current study investigates the effect of different vegetation arrangements on OTC in a tropical urban public square (Independence Arcade in Colombo) using micrometeorological fluid dynamics (CFD) modeling validated by field measurements. Air temperature (Ta), relative humidity (RH), wind speed (WS), and wind direction (WD) were measured at 1.5 m above ground level as the inputs for the ENVI-met simulation model to assess the cooling performance of proposed scenarios employing Physiological equivalent temperature (PET). Nine scenarios were developed using trees with high leaf area density (LAD) and spherical canopy form to compare OTC improvements of cluster, random and individual planting patterns, and the size of trees (large, medium, small). The results showed that vegetation improves the OTC levels irrespective of the planting pattern. However, linear individual planting pattern with large trees performed the best cooling performance, and scenarios were ranked according to improved PET values. Vegetation parameters are recommended to arrange in different ways to achieve OTC and aesthetics. The study was limited to the existing vegetation database of the ENVI-met software package, but further research could consider the context-specific tree species and the impact of combined landscape scenarios using grass, shrub coverage, and water bodies to find proper arrangements to improve the microclimate and OTC. This study guides urban planners and landscape architects to assess the cooling performance of the proposed designs and arrange urban vegetation to create thermally comfortable urban outdoors in the tropics. 
 Keywords: Vegetation arrangement, Urban square, Outdoor thermal comfort, ENVI-met, PET
 Acknowledgement: Authors acknowledge the assistance of the Accelerating Higher Education Expansion and Development (AHEAD)-DOR Grant, funded by the World Bank

The outdoor thermal environment is an important factor when measuring the livability of a city. Residents will avoid intense heat by reducing their outdoor activities, which decreases the vitality of a city and increases the energy consumed for air conditioning. Outdoor thermal comfort has a great impact on outdoor activities; therefore, we need to evaluate and design the urban outdoor thermal environments in cold regions to improve the outdoor thermal comfort level. In this study, we conducted a questionnaire survey to assess the outdoor thermal comfort and adaptive thermal comfort in four different urban forms in Xi'an during July 2019, and measuring meteorological parameters, such as the temperature, relative humidity, wind speed, and black bulb temperature. The results are showed as follows. (1) In the cold study area, urban residents generally perceived the outdoor climate as relatively hot during the summer. (2) The participants exhibited psychological and physical adaptations in terms of their thermal comfort. In particular, when the PET was 30°C, the MTCV was about 1.25 points higher in the later summer period than the early summer period. (3) The neutral PET differs among regions, and it is affected by the climate zone and latitude. Comparisons of our results with thermal comfort studies in different regions such as Singapore and Umeå in north Sweden showed that the thermal comfort is correlated with the regional climate and latitude. The neutral PET is higher in tropical regions. Our findings support the theoretical understanding of adaptive thermal comfort in cold regions and they provide a reference for formulating policies related to adaptive thermal comfort.

Linking landscape spatial heterogeneity to urban heat island and outdoor human thermal comfort in Tokyo: Application of the outdoor thermal comfort index

Urban outdoor space is an important activity place for residents, and its thermal environment directly affects residents’ quality of life and physical and mental health. Due to global climate change and the acceleration of urbanization, the outdoor thermal comfort of urban residents has seriously declined, causing more and more scholars to pay attention to this problem and to carry out research. This paper summarizes the development history and evaluation principles of outdoor thermal comfort evaluation indices and sorts out the methods for achieving outdoor thermal comfort. This paper reviews the effects of urban climate, local microclimate, physiological, psychological, social, and cultural factors on outdoor thermal comfort. In addition, strategies for improving thermal comfort in urban outdoor spaces are discussed from the aspects of urban geometry, vegetation, surface materials, and water bodies. Finally, the existing problems and development directions of current urban outdoor space thermal comfort studies are pointed out. This review paper can provide a reference for the scientific planning and construction of urban outdoor spaces to improve people’s thermal comfort.

Investigation of outdoor thermal sensation and comfort evaluation methods in severe cold area