Summer Thermal Comfort Research Articles

Estimation of Longwave Radiation Intensity Emitted from Urban Obstacles in Each Direction Using Drone-Based Photogrammetry

Longwave radiation is a crucial factor affecting human thermal comfort and thermal stress, especially in outdoor spaces in summer, owing to the vast effect of longwave radiation emitted from high-heated asphalt roads, building walls, and automobiles. Although controlling the longwave radiation environment to improve thermal comfort in summer is crucial, the prediction of the longwave radiation environment is frequently conducted only at the assessment stage of the final proposal because of the high computational cost of radiation calculations and unsteady heat balance analysis considering multiple reflections. This is a significant constraint for the design of urban and architectural environments. A previous study proposed a method to rapidly estimate the longwave radiation environment based on a point-by-point method with longwave radiation intensity distributions of the heat sources. To use this method, 3D models of the geographical objects in urban areas, such as buildings and trees, must be accurately generated, and these models should have information on the longwave radiation emitted in each direction from each object. However, no specific examples of a 3D model and longwave radiation intensity distribution have been presented. In this study, a 3D modeling method for geographical objects in urban areas with longwave radiation information based on drones and photogrammetric techniques was utilized. Moreover, a 3D model of a small-scale building was generated. A longwave radiation intensity distribution was produced for the building. Based on the distribution data, the directional characteristics of longwave radiation were discussed, and the availability of the proposed method was assessed.

The Impact of Different Types of Trees on Annual Thermal Comfort in Hot Summer and Cold Winter Areas

Trees positively improve the annual thermal comfort of the built environment in tropical areas, where climate change is slight throughout the year. However, for areas with high changes in climate all year, the current studies have only explored the summer cooling performance of trees without the impact of different types of trees on annual thermal comfort, especially in cold seasons. Therefore, to quantify the impacts and scientifically guide the optimization of green space layout in hot summer and cold winter areas, this study selected Changsha City as the study area and analyzed how the annual thermal comfort is affected by evergreen trees and deciduous trees, which are two common types of trees in hot summer and cold winter areas. The analytical results indicated that the difference in the effect of deciduous and evergreen trees on outdoor thermal comfort was insignificant in summer, where the difference in the monthly mean PET for the three summer months was slight, being 0.28 °C, 0.14 °C, and 0.29 °C, respectively. However, evergreen trees greatly exacerbated winter cold compared to deciduous trees, with a monthly mean PET decrease by nearly 1.0 °C and an hourly PET reduced by up to 3.57 °C. The difference is mainly attributed to the absorption and reflection of solar radiation by the tree canopy, as well as the cooling and humidifying effect of the tree leaf. In hot summer and cold winter areas, outdoor thermal comfort is still in the “comfortable” and “slightly warm” acceptable stage despite the warming effect of deciduous trees in the spring and autumn seasons. Planting evergreen trees is an inevitable thermal mitigation choice for tropical areas. However, for the areas with high annual climate change, such as hot summer and cold winter areas in China, a change in empirical tree planting patterns and selecting deciduous trees where appropriate will improve year-round outdoor thermal comfort.

Developing simplified metamodels for assessing urban park cooling effect on the thermal behavior of the residential buildings: A case study in Nantes, France during a heat wave

The objective of this research is twofold. First, it aims to evaluate the impact of an urban park on the thermal behavior of residential buildings. Second, it focuses on developing and validating metamodels for predicting the cooling needs and summer thermal comfort of three types of residential buildings: single-family houses (Low-rise), small collective housing (Mid-rise), and large collective housing (High-rise). The metamodels are created through regression analysis, using a set of dynamic thermal simulations conducted with TRNSYS software. The number of dynamic simulations is efficiently reduced using the design of experiments method, and the accuracy of the metamodels is further validated through additional simulations. This study was conducted considering the climate weather conditions of the city of Nantes, France. The results demonstrate that an urban park can achieve a maximum reduction of 12.53 % in cooling needs and a 12.50 % maximum reduction in degree hours of discomfort, particularly when the building is protected from solar radiation. Furthermore, developed metamodels show high accuracy with regression coefficients over 0.96. This study aimed to create a decision support tool for local government departments to optimize urban cooling, improve thermal comfort, and reduce cooling loads in buildings by guiding the design of parks and their surrounding built environment.

Improving kitchen thermal comfort in summer based on optimization of airflow distribution

To quantitatively analyze the comfort of kitchen environment, this paper presents a thermal comfort analysis method for kitchen with air-conditioned range hood. It corrects the deficiency in the original comfort formula involving humidity, thereby reasonably quantifying the impact of the cooling airflow from air-conditioning, including humidity, on kitchen thermal comfort. By adjusting the structural parameters of the air conditioning system, the airflow distribution in the kitchen space during summer has been optimized, thereby further enhancing its thermal comfort. This method employs Fluent analyses and its User-Defined Functions (UDF) to analyze the indoor flow field, temperature, humidity, and the distribution of PMV-PPD within the kitchen equipped with air-conditioned range hood. Additionally, experimental data are applied to validate the accuracy and effectiveness of the simulation model. The results indicate that under high temperature climate conditions in summer, air-conditioned range hood significantly enhances the thermal comfort of kitchen environment during cooking. Moreover, optimal thermal comfort for both the kitchen space and local respiratory area of the human body is achieved when the air supply angle is set at 45°, the air conditioning outlet flow rate is 5.5 m3/min and the air supply temperature is set at 21 °C. Compared to the initial operating conditions, Human thermal sensitivity weighted PMV decreased by 98.17 %, and the weighted PPD decreased by 82.07 %. This study provides valuable insights for the design and operation of air-conditioned range hoods, contributing to improved thermal comfort and energy efficiency in residential kitchens.

Integrated effect of aspect ratio and tree spacing on pedestrian thermal comfort of street canyon.

Increasing heat stress in urban environments due to climate change has a significant adverse impact on human work and daily life. Street canyons as the main component of the underlying surface of the city and the main place of residents' activities, a comprehensive understanding of street morphology and tree planting practices can help to improve thermal comfort. Based on survey data and field experiments, this study designed 30 scenarios and employed ENVI-met model (version 5.0.3) to quantify the effect of street aspect ratio (H/W: H is building height and W is street width) and tree spacing (TS) on pedestrian thermal comfort in two differently oriented streets (north-south and east-west) in Taiyuan, China. Results showed that H/W ratio and TS significantly influenced the street thermal comfort mainly owing to shading. H/W ratio played a pivotal role in reducing mean radiant temperature (Tmrt) and physiological equivalent temperature (PET), and was negatively correlated with Tmrt and PET. Compared to no-tree scenarios, street trees significantly improved thermal comfort (mean reductions of Tmrt and PET were 12.74℃ and 5.66℃, respectively), and PET and Tmrt were significantly negatively correlated with TS. The improvement effect of street trees on Tmrt and PET in east-west oriented street was better than north-south oriented street. H/W = 1.0 and TS = 6m appeared as the proposed combination to mitigate the summer thermal comfort in the temperate monsoon climate zone. These quantitative results provide new insights into renewal and design strategies for future urban planning.

Design optimization of an assisted living facility to improve summer thermal comfort in warming climates

Assisted living facilities with optimal summer thermal comfort are necessary to ensure improved quality of life for the older individuals in warming climates. Older individuals are exposed to higher mortality risks during periods of excessive heat. This study aims to identify and optimize key design variables for a passive house certified assisted living facility in Belgium with high comfort expectations using EnergyPlus to improve indoor thermal comfort during extreme climates. The sensitivity analysis used the Standard Regression Coefficient method with Latin Hypercube Sampling for eighteen design variables under four categories: layout, envelope, operation, and system. The analysis identified flat roof and external floor insulation as the most influential parameters, whereas lighting gain and cooling setback temperature were the least influential parameters. Furthermore, optimizing the reference building with the most sensitive design variables using a genetic algorithm based on the NSGA-II method found ideal configurations that would ensure minimum thermal discomfort hours during extreme summers. The study findings provide an evidence-based approach for building engineers and designers for early-stage design of assisted living facilities that maintain optimal comfort in mixed humid climates of Europe.

In situ air change rate estimation from metabolic CO2 measurement. Summer experimental campaign in a single-family test house

Night ventilation is one of the most promising approaches for reducing the cooling-energy consumption of buildings while improving the summer thermal comfort of occupants. More accurate measurement of the air change rate (ACR) through window openings may help promote this approach. Indeed this is still an active research topic that requires well-controlled experimental data. This article aims to expand the application scope of the tracer gas methodology for dynamic estimation of ACR in residential buildings. Controlled inputs, such as human metabolic CO2 emissions and various window-opening configurations, are chosen to represent the actual use of a single-family house during the cooling season. The measurement dataset – including weather on site, wind on the walls, indoor air speed, temperature, relative humidity, CO2 concentration at various positions and at a time resolution of 1 min – is processed for sharing. Wind fluctuation on the external wall emphasizes the dynamic nature of ACR. Indoor temperature and CO2 concentration measurements showed a mean spatial heterogeneity of 1.0 °C and 625 ppm, respectively. Indoor CO2 levels are low (<2000 ppm), which is a limitation in the use of the tracer gas equation. Thus, the potential of the dataset for dynamic ACR estimation is discussed by introducing and analyzing two indicators. Finally, the ability of the dataset to compute dynamic ACR is demonstrated through deterministic solving of the tracer gas equation.

Multi-objective optimization for generative morphological design using energy and comfort models with a practical design of new rural community in China

In recent years, the development of new rural communities has emerged as a pivotal new trend in china, aimed at enhancing energy efficiency and residential comfort in rural regions. This study introduces a multi-objective optimization design framework for the morphological design of residential area, with a focus on performance objectives such as building energy use intensity, summer thermal comfort, and winter thermal comfort. A case study of a new rural community design project in Hongnan Village, Yancheng City, was conducted. Utilizing the Rhino-Grasshopper parametric platform, this study undertook parametric modeling, performance simulation, and multi-objective optimization to receive the Pareto-optimal solutions. ParetoResults indicate that in the Pareto-optimal morphology scheme for the Hongnan Village community, open spaces are predominantly located on the upwind side with respect to the prevailing summer winds of the site. The number of duplex houses is often 28, and the building orientations are predominantly aligned at 23°, mirroring the direction of the surrounding structures. There is a significant correlation between residential unit configuration, building spacing, and energy use intensity, with correlation coefficients of 0.53 and −0.43, respectively. This study would like to offer valuable insights into the energy-efficient design of new rural communities, thereby contributing to the creation of a more sustainable and habitable rural living environment.

Potential of Nature-Based Solutions to Diminish Urban Heat Island Effects and Improve Outdoor Thermal Comfort in Summer: Case Study of Matadero Madrid

Urban heat island effects and climate change are climatic phenomena responsible for periods of extreme heat in summer which severely impact citizens’ well-being and health. In this alarming context which questions the livability of our cities, Nature-Based Solutions (NBSs) are considered an unavoidable component of the complex strategy in diminishing urban temperatures. The present work aims to show the relevance of NBSs in urban temperature regulation through the estimation of their potential to improve outdoor thermal comfort of the heritage site Matadero Madrid. To this end, this article evaluates the effects of a scenario combining different solutions including NBSs and identifies which solutions are the most effective. The results show that this scenario has an impact on direct solar radiation and wind speed but does not affect air temperature and relative humidity. Furthermore, even if this scenario combining a fabric canopy, tree canopy, and green area significantly improves thermal conditions, it does not allow us to reach an optimal level of thermal comfort for visitors. To consider the implementation of more meaningful interventions, existing legal, administrative, and cultural limitations of the case study should be omitted. This would enable us to identify which restrictions could be adapted, thus unlocking the adaptation potential of Matadero Madrid.

Employing the spray system to alleviate the thermal action of air-conditioning in summer

Widespread adoption of air-conditioning significantly enhances indoor thermal comfort in summer, but the heat dissipation from these outdoor units contributes to an increase in ambient air temperature, exacerbating urban heat island effects. Consequently, as outdoor thermal conditions worsen, the energy consumption associated with air-conditioning is likely to escalate. The spray system becomes a suitable choice due to the obvious advantage of heat absorption through the droplet evaporation. To assess the effectiveness of the spray system in reducing heat release, a comparative study was conducted between two identical buildings with the same air-conditioning system, but only one of which incorporated the spray system. Three installed locations are considered with the spray location in inlet (Case 1), outlet (Case 2) and both inlet & outlet (Case 3) of outdoor units. The results demonstrated the average temperatures of air outlet were reduced by 4.0 °C, 6.3 °C, and 7.9 °C for Cases 1–3, respectively, accompanied by a reduction in energy consumption of the air-conditioning system by 18.8%, 13.9%, and 37.3% respectively. The most significant benefits were observed when the spray location was installed in both outdoor unit inlet and outlet (Case 3). The spray system established a virtuous cycle in heat dissipation improvement, evaporation enhancement, and air temperature reduction.

La traduction des vagues de chaleur, un frein au développement des réseaux de froid : Une étude empirique en France

In the context of climate change, heatwave events are becoming more frequent, severe, and prolonged, exacerbated in urban areas by the effects of heat islands. The need for summer thermal comfort and coolness emerges as a major health issue. This study is based on exploratory research conducted with 33 stakeholders involved in heat and cold networks, aiming to understand how these stakeholders engage with the debate on heatwaves and what solutions they envision. We identify that the limited growth of cold networks is due to the absence of climate-related considerations by key actors, even though these networks offer a solution to mitigate climate change and adapt to heatwaves.

Energy Performance of Vernacular Architecture in Various Desert Climates

Summer 2022 is officially the 2nd hottest summer in France since 1900. It resulted in three episodes of heat waves over a total of thirty-three days. Heat waves are characterized by very high temperatures (exceeding seasonal averages) during the day and night for at least three consecutive days. According to initial estimates, it caused a surplus of more than 11,000 deaths in 2022 in France. In France, despite new thermal standards, the thermal comfort of new housing in hot weather remains very inadequate. Thanks to these empirical developments vernacular architecture has demonstrated its adaptation in particularly harsh climates. The objective of this research is to understand the design strategies of four vernacular houses located in four deserts (Algerian Sahara, Arizona, Libyan desert, and Yemen) to ensure summer comfort in hot environments. The thermal behavior of these four vernacular houses has been studied through dynamic thermal simulations performed with the software ‘ArchiWIZARD’, using the same climate conditions. The results are interpreted in terms of operative temperature and related to building compacity. They show how vernacular architecture, located in desert climates, considered summer thermal comfort with design strategies. The thermal inertia of the four case studies is characterized by the daily thermal damping. The results also show the contribution of natural night ventilation on the energy performance of these four vernacular architectures in hot and arid climates.

Dynamic modeling of airflow rate through window openings based on CO2 data

Better estimation of air change rate in naturally ventilated buildings is a key for supporting passive summer thermal comfort strategies. In window aired configurations, this estimation is challenging either with measurements or building simulation methods. In this study, we describe and apply the state space modeling methodology based on the carbon dioxide concentration (CO2) mass balance equation to a simple test case with numerically generated data. We show that a two-state CO2 / Air Change Rate model is suitable. As a modeling novelty, we demonstrate the benefit of improving the formulation with a variable diffusion term for the air change rate state equation. From the test case study findings, we emphasize that a lower interior-exterior CO2 difference results in weaker performance and we list some prospects for future work.

Field Study to Compare and Evaluate Summer Thermal Comfort of School Buildings with Different Moderate Thermal Mass in Their Building Elements

Previous studies show that moderate thermal mass in school building elements can positively impact the winter indoor thermal environment in a temperate climate with mild, humid winters. Based on a field study, this research contributes new physical data of the summer indoor thermal environment of Auckland school buildings with different designs of moderate thermal mass in their building elements to add to the previous winter field-study data and demonstrates that a school building with moderate thermal mass is adequate in a temperate climate with mild, humid winters and warm, dry summers. This field study compared and evaluated the summer indoor thermal environment of classrooms with different moderate thermal mass in their building elements during the summer school term and the summer school holidays. This study found that a classroom with thermal mass in its building elements has 19% to 21% more time in summer than a classroom without any thermal mass in its building elements when indoor air temperatures are within the thermal comfort zone, which was solely impacted by the building’s thermal performance. This study established a suitable research method to analyse the field-study data and identify the differences in the indoor thermal environments of the school buildings with different designs of moderate thermal mass in their building elements.

Impact of Material Solutions and a Passive Sports Hall’s Use on Thermal Comfort

High outdoor temperatures and thermal gains due to solar radiation, which penetrates the interior of buildings as the climate warms up, pose a major challenge to maintaining thermal comfort in passive sports facilities. Superbly insulated and airtight envelopes, specific microclimatic requirements and very high user activity can easily lead to overheating and thermal imbalance during summer. This paper focuses on the influence of the varying thermal capacity of external walls and night-time cooling on thermal comfort in a passive sports hall building. Based on experimental studies of the thermal conditions in the building, a model of it was created in Design Builder. Through simulation, the program initially analysed the thermal conditions that arise under different envelope assemblies. Two different ways of cooling the building at night were then analysed: mechanical and natural. The results presented showed that in a well-insulated sports hall with a large volume, the type of wall material alone had only a limited influence on thermal comfort in summer. In contrast, night-time cooling in integration with the accumulation of cold in the building’s structural components had a significant impact on protection against overheating during the summer. The type of envelope material is even more important when night-time air exchange is high. Intensive natural ventilation is associated with the highest number of hours in the comfort range—28.1–32.4% more hours in relation to the variant without night ventilation. The use of mechanical ventilation, operating at night at maximum capacity, will result in an increase in the number of hours with air temperatures in the −0.5 &lt; PMV &lt; +0.5 range by only 14.1–21.3%. The high thermal mass of the envelope, combined with adequate ventilation, reduces the occurrence of very high indoor air temperatures, thus alleviating the nuisance of overheating. The maximum internal air temperature during the day is lower by 2.4–3.3 K, compared to the case when no night ventilation is used. Mechanical ventilation operating at its maximum capacity can reduce the maximum internal temperature by 1.2–1.6 K.

A Simulation Study of the Impact of Urban Street Greening on the Thermal Comfort in Street Canyons on Hot and Cold Days

The urban heat island effect has become a widely concerning issue worldwide. Many researchers have made great efforts to improve the summer thermal comfort of urban street canyons by optimizing street greening. Relatively less research has focused on how to improve the thermal comfort of street canyons by optimizing street greening during cold days. Many researchers have proposed strategies to improve the summer thermal comfort of street canyons using road greening. This may have a significant negative impact on the winter thermal comfort of street canyons due to the lack of consideration of the impact on hot and cold days simultaneously, especially when the road green space is mainly composed of evergreen tree species. We aimed to explore the impacts of urban street greening on thermal comfort on hot and cold days at the same time. We used Zhutang West Road in Changsha, China, as an example and built six different models to explore the impacts of the street vegetation types, number of street trees, tree heights, crown widths, and Leaf Area Index on the thermal comfort of the street canyon. In addition, we also considered the impact of different building features and wind directions on the thermal comfort of the street canyon. We employed ENVI-met (version 5.5.1) to simulate different urban street greening models. The results show that the model with a high tree canopy density, tall trees, large and dense crowns, and sufficient building shade has good thermal comfort on hot days (the average physiological equivalent temperature (PET) is 31.1 °C for the study period) and bad thermal comfort on cold days (the PET is 13.3 °C) when it is compared with the other models (the average PETs are 36.2 °C, 31.5 °C, 41.5 °C, 36.2 °C, and 35.5 °C, respectively, on hot days and for other models). In addition, the model with a very large number of short hedges has a positive impact on thermal comfort during hot days (the PET is 31.1 °C). The PET value of another comparable model which does not have hedges is 31.5 °C. Even if the model with a small building area has good ventilation, the small building shade area in the model has a more obvious impact and the model has relatively good thermal comfort during cold days (the PET is 14.2 °C) when it is compared to models with bigger building areas (the PET is 13.9 °C). In summer, when the wind is parallel to the direction of the street canyon, the wind speed in the street canyon is high and the model has relatively good thermal comfort (the PET is 35.5 °C) compared with another model which has different wind direction and lower wind speed at the street canyon (the PET is 36.2 °C). In winter, when the wind is perpendicular to the direction of the street canyon, buildings and trees have a strong windproof effect and this is beneficial to the improvement of thermal comfort (the PET is 15.3 °C for this model and 13.9 °C for another comparable model). This research lays a solid foundation and encourages people to think about the impact of building and tree composition and configuration on the thermal comfort of street canyons during hot and cold days simultaneously.

Impact of Canopy Coverage and Morphological Characteristics of Trees in Urban Park on Summer Thermal Comfort Based on Orthogonal Experiment Design: A Case Study of Lvyin Park in Zhengzhou, China

As an integral part of urban forests, urban parks play a vital role in mitigating urban heat islands (UHI) and providing residents with comfortable outdoor recreational plots. For high-quality use of the trees in regulating the thermal comfort of urban parks, previous studies primarily focused on the microclimate variations caused by tree coverage and morphological features separately. However, there is still a lack of systematic understanding of how tree canopy coverage (TCC) and its morphological elements, including leaf area index (LAI), trunk height (TH), and crown diameter (CD), combined affect the thermal comfort in the urban park. This study employed an orthogonal experiment design and ENVI-met software to simulate the microclimate of various multi-factor combination models in the case of a typical urban park in a temperate continental climate zone in China, analyzing the simulated result through physiological equivalent temperature (PET). Results show that the contribution ratio of various elements to the thermal environment vary over time. In studied elements, the contribution ratio of TCC to PET is consistently higher than 50% during the morning, midday, and evening periods, reaching a peak of 67% in the evening. The maximum contribution ratios for CD, TH, and LAI occur during midday, morning, and midday, respectively, with corresponding contribution ratios of approximately 22%, 10%, and 9%, respectively. The ranking of elements affecting thermal comfort in the urban park generally is TCC, CD, LAI, TH throughout the day, apart from the morning, when the influence of TH is greater than LAI. The optimal combination of elements is 85% TCC, 4m TH, 3.9 LAI, and 7m CD, and thirteen combinations of element cases meet the thermal comfort requirements during summer. The research findings highlight the significance of optimizing the configuration of trees in creating a more comfortable and inviting space for human activities.

On the effectiveness of passive controls for summer thermal comfort in highly insulated dwellings

ABSTRACT Among environmental controls, solar shading and ventilative cooling are widely considered as key passive strategies for limiting the overheating risks in buildings. While their application is encouraged through Energy Performance of Buildings Directive regulations, several studies have shown that summer thermal comfort in heating-dominate temperate climates still requires deeper investigation, particularly in low-energy residential buildings. Based on qualitative and quantitative data collected through surveys and monitoring in 147 highly insulated houses in Wallonia (Belgium), this paper gives an overview of the implemented passive strategies and discusses their effectiveness. Statistical tests are conducted to evaluate their impact on both perceived and measured indoor conditions. In general, the results highlight a limited impact of the implemented strategies, questioning their proper operation. Operational modes for environmental controls thus appear crucial, and should better respond to occupants’ needs, preferences and control opportunities. At a more general level, the study calls for a better understanding of the barriers inhibiting successful integration and operation of environmental controls, in order to effectively reduce overheating risks in residential buildings and limit future diffusion of active cooling systems with their induced environmental impacts.

The Influence of Residential Block Form on Summer Thermal Comfort of Street Canyons in the Warm Temperate Zone of China

The residential block is the cognitive unit for residents to constitute urban imagery. As one of the most frequently used urban outdoor public spaces by residents, the thermal comfort of street canyons is an essential indicator for assessing sustainable and livable cities. The problem of the uncomfortable summer climate in the warm temperate zone of China has not been adequately studied. The study aims to analyze the influence of the building layout form of residential block units and block configuration on the outdoor summer thermal comfort of street canyons. Outdoor air temperature (Ta), mean radiant temperature (Tmrt), wind speed (Va), and physiological equivalent temperature (PET) were simulated using ENVI-met. A new index, PETws, was introduced based on a statistical analysis of the PET index to assess the overall street canyon thermal comfort of the block. The results indicate that the number of rows of buildings in the building row layout has a more significant effect on the summer thermal comfort PET of street canyons than the number of columns in the warm temperate zone, especially on N–S-oriented streets. Reducing the number of rows can increase the overall thermal comfort PETws of street canyons by a maximum of 2.2%. The best choice for the number of building columns is two columns. Adopting different block configurations can increase the thermal comfort PETws of street canyons by up to 2.5%. An optimal block form has been created to improve the overall street canyon summer thermal comfort of the block.

A Parametric-Simulation Method to Study the Interconnections between Urban-Street-Morphology Indicators and Their Effects on Pedestrian Thermal Comfort in Tropical Summer

Numerous studies have explored the impact of urban morphology and geometry on outdoor thermal comfort, intending to provide practical guidelines for urban designers. However, research findings have been inconsistent, in part due to differences in the climatic settings and the investigated heat-stress indicators. This study proposes a parametric-simulation framework to observe the behavior of thermal comfort according to the possible combinations of building density (BD), street aspect ratio (AR), and orientation. Conducted specifically under a hot-and-humid tropical-savanna summer condition, the study found that building density and aspect ratio were negatively correlated to the Universal Thermal Climate Index (UTCI), with R2 coefficients of 0.99 and 0.91, respectively. The UTCI was improved by a 1.0 °C per 10% increase in BD and by a 1.02 °C per unit of AR increase. The performance of street orientation was significantly influenced by wind direction, and strong inter-influences were found between the three morphology factors. These findings are useful guidelines not only for designing urban morphology but also for intuitively identifying the need for complementary vegetation and cooling materials when morphology indicators cannot reach their efficiency targets (e.g., when AR &lt; 3.0 or building density is limited by local regulations and project specifications).