Hot-humid Regions Research Articles

Optimizing Thermal Comfort in Urban Squares of Hot-Humid Regions: A Case Study Considering Tree Growth, Species, and Planting Intervals

The worsening urban thermal environment has become a critical challenge in many cities. Trees, as vital components of urban green spaces, provide multiple ecosystem services, especially in improving the microclimate. However, limited studies address how morphological changes during tree growth influence their cooling benefits. This study combined the tree growth model with ENVI-met to simulate 27 scenarios in a subtropical urban square, considering three planting intervals, three urban tree species, and three growth stages to evaluate their daytime thermal impacts. The key findings include: (1) Tree size and planting intervals are more important than tree quantity in enhancing thermal comfort. (2) Reducing intervals by 2 m enhances cooling effects but minimally affects PET (physiological equivalent temperature). (3) Increasing DBH (diameter at breast height) significantly improves cooling. For every 10 cm increase in DBH, Michelia alba, Mangifera indica, and Ficus microcarpa L. f. reduced solar radiation by 19.54, 18.09, and 34.50 W/m2, and mean radiant temperature by 0.61 °C, 0.68 °C, and 1.35 °C, respectively, while decreasing PET by 0.23 °C, 0.23 °C, and 0.46 °C. These findings provide empirical evidence and practical recommendations for designing comfortable open spaces in subtropical cities.

Wind-Catchers: Tracing Their Historical Identity as Skyline Features and Cooling Solutions in Architecture

Wind catcher towers, known as Baad-geer in Farsi language, are a distinctive feature of the vernacular architecture in both hot-arid and hot-humid regions of Iran and in the middle East. Functioning as a passive cooling system, these structures regulate indoor temperatures during summer by harnessing natural airflow. Installed on the highest part of the buildings, mostly residential, wind catchers have been always exposed to fast deterioration, hence, tracing their exact date of origination and historical evolution seems challenging. This paper adopts a multidisciplinary approach, drawing on insights from archaeology, literature, and architectural studies to investigate the origins of wind catchers. The descriptive analytical methodology has been adopted for processing the data. Based on the available evidence, the research concludes that the origin of wind catchers goes back to pre-Islamic period in Iran.

Influence of view factors on outdoor thermal comfort of residential areas in hot-humid regions.

Sky View Factor (SVF) is commonly used to describe the impact of urban geometry on the urban thermal environment. Shading effects from plants and buildings also exert a considerable influence. To investigate the influence of view factors on outdoor thermal comfort in residential areas, we employed the Physiological Equivalent Temperature (PET) and view factors (SVF, TVF, BVF) as indicators to determine outdoor thermal comfort and the quantity of shaded spaces. Thermal measurements collected from 13 points in Guangzhou, China, Our findings revealed that high TVF points exhibited more stable air temperature throughout the daytime, with average temperature differentials ranging 0.4-1.9°C lower than other points. Air temperature demonstrated a positive correlation with SVF (R2 = 0.53), while exhibiting a negative correlation with TVF (R2 = 0.45). Additionally, shading provided by plants and buildings manifests heterogeneity. At similar SVF levels, points predominantly shaded by plants (TVF > BVF) showcased lower Mean Radiant Temperature (MRT) and PET compared to points shaded mainly by buildings (BVF > TVF). The maximum reduction in air temperature and PET reached 1.1°C and 1.2°C, respectively. BVF exerted greater influence earlier in the morning, as solar altitude angle rises, the average thermal parameters of sites with BVF > TVF escalated rapidly until eventually surpassing sites with TVF > BVF. Last, superior thermal conditions were only ensured under high shading conditions. When the effective shading ratio of plants and buildings diminished (SVF > 0.3), the microclimate of measurement points might be impacted by the long-wave radiation from the underlying surface.

Research on the coordinate regulation behavior of window opening and split air conditioners usage during summer in mixed-cooling houses in hot-humid regions

In the hot-humid regions of South China, it is common for residents to utilize a combination of window opening and split air conditioners to cool their houses during summer. However, existing research focuses on investigating either window opening behavior or air conditioner usage behavior respectively, lacking a linkage study between these two approaches. Addressing this research gap, a novel coordinated regulation behavior model was developed by integrating both window opening and air conditioner usage behaviors. Due to different coordinate regulation modes, the tolerance temperature range in summer varies in mixed-cooling houses. Additionally, a degree of coordination is introduced to signify the level of overlap between window opening and air conditioner usage behaviors, indicating the uncertainty involved in choosing between these two actions. Moreover, residents exhibit a dynamic approach to switching between cooling methods, characterized by a transition range of approximately 2 °C rather than relying on a fixed temperature value. Notably, the simulated energy consumption results demonstrate a significant energy consumption disparity of up to 71 % among different behavior patterns. This study contributes to the academic understanding of the complex interactions between window opening and air conditioner usage and lays the foundation for achieving precise energy consumption simulation of mixed-cooling houses.

Boosting mold aerosol reduction and dehumidification performance in liquid desiccant systems using airborne ultrasound: An experimental study

Indoor mold exposure in hot-humid regions poses considerable risks to public health and food security. Ensuring safe, durable, and energy-efficient air disinfection is crucial for the air-conditioning field. While liquid desiccant air-conditioning (LDAC) systems eliminate condensation-related mold proliferation, their capability to combat airborne mold spores is limited due to the spores' robust resistance. This paper explores a novel airborne ultrasound-assisted liquid desiccant air-conditioning (US-LDAC) system. Experiments were conducted using culture-based methods to compare the system's disinfection capacities against Aspergillus niger spores, a desiccant-resistant species, under ventilation, liquid desiccation dehumidification, and airborne ultrasound-assisted liquid desiccant dehumidification modes. Moreover, the viability and morphological changes of mold spores exposed to airborne ultrasound, with and without liquid desiccants, were analyzed to verify the disinfection effectiveness and extrapolate the improving mechanisms. The results show that irradiating low-intensity airborne ultrasound (∼127 W, harmless mechanical waves) into the dehumidifier significantly increased the disinfection efficiency by 50 % and the dehumidification rate by over 90 % when airflow passed through the dehumidifier (∼0.4 s). The enhanced disinfection is attributed to ultrasonic cavitation, which facilitates the rupture of the desiccant-captured spores through microstreaming-induced shear forces. Notably, the improvements were more pronounced in humid air and with dilute desiccant solutions, suggesting that efficiency can be maintained with lowered desiccant concentrations. The US-LDAC system was particularly adept at removing mold aerosols (2.1–3.3 μm) which are easily inhaled. These findings propose a promising avenue for retrofitting existing LDAC systems to effectively reduce airborne molds and enhance dehumidification, thereby protecting indoor air quality.

Hygrothermal resilience of typical lightweight steel-framed wall assemblies in hot-humid areas under future climate uncertainty

Ensuring the hygrothermal performance of lightweight steel-framed (LSF) wall assemblies is critical for the sustainability of LSF buildings in hot-humid regions; however, climate change poses new challenges. Therefore, this study aimed to bridge the gap in understanding the characteristics of hygrothermal load changes and the hygrothermal resilience of different LSF wall assemblies. Future climate data for each decade of this century (from 2030 to 2090), under various carbon emission scenarios, were generated based on a typical meteorological year (TMY) for hot-humid areas to evaluate the impact of climate change on hygrothermal loads. The hygrothermal resilience of four typical LSF wall assemblies, with either ventilated rainscreen cladding or face-sealed stucco cladding, with or without external insulation, was evaluated through simulation and comparative analysis. The results indicated that the thermal load would increase with increasing carbon emissions and over time, with the annual average external temperature peaking at 25.8 °C by the end of this century. The frequency of months with a high or critical moisture load would increase, although the moisture load may fluctuate across scenarios and years. Consequently, the cooling and dehumidification loads may increase by 52–60 % and 40–88 %, respectively. The hygrothermal risk within the walls may increase, with maximum increases of 2.8–8.0 % in the annual average relative humidity, 2.7–3.0 °C in the annual average temperature, and 10–35 % in the wetness duration. However, the impacts could be reduced by using ventilated rainscreens and external insulation, with further precautions needed to mitigate the increasing hygrothermal risk in areas with thermal bridges and rainwater leakage, as well as at the outer interface of the external insulation. These findings could provide a reference for the design of LSF buildings adapted to climate change in hot-humid areas.

Assessing the winter indoor environment with different comfort metrics in self-built houses of hot-humid areas: Does undercooling matter for the elderly?

Thermal comfort in housing is vital for well-being. Despite hot and humid regions experiencing shorter cold periods compared to heatwaves, vulnerable populations are susceptible to threats from cold snaps. However, existing research overlooks undercooling risks in hot regions during winter. This study examines self-built houses in densely populated, hot and humid areas, mainly occupied by elderly residents. We conducted an on-site measurement recording hourly indoor air temperature, humidity, and black globe temperature during wintertime. Two thermal comfort metrics (aPMV and adaptive regression model) and two resilience metrics (SET degree-hour, Hours of Safety) were used to quantify thermal conditions during cold periods under current and future climate conditions. The results show that undercooling hours in recent years exceed 90 % of wintertime using aPMV index and adaptive regression models. Under future climate scenarios (Representative Concentration Pathways), undercooling hours only decrease by 10 %–25 % from 2020 to 2100 across all metrics. Extreme cold events in 2018 saw SET degree-hours double the thermal resilience threshold, while they pose health risks to the elderly for up to 21 days according to the HOS metrics. This study aims to identify the importance of addressing winter thermal comfort in hot and humid regions and to assess the risk posed by cold snaps to vulnerable populations. By quantifying these risks, the study contributes to better decision-making regarding hot-humid region housing thermal retrofit strategies for architects, engineers, and other stakeholders.

ARCHITECTURAL SOLUTIONS OF SCHOOL BUILDINGS IN HOT-DRY AND HOT-HUMID REGIONS OF IRAN

Iran is characterized by a diverse climate spectrum, covering a temperate and humid climate in the north of the country and in the coastal areas of the Caspian Sea, a cold climate in the west and in the Zagros mountain range, as well as hot dry and hot-humid conditions prevailing in the central part , in the east, in the Persian Gulf region and in the south of the country. This article focuses on the analysis of architectural features of school buildings in hot-dry and hot-humid regions of Iran, taking into account the specifics of the climate of these areas. The main attention is paid to effective orientation of buildings in relation to the sun, optimization of air conditioning systems, adaptation of lighting to the needs of educational spaces, use of green spaces to create shading, as well as selection of the form and design of school interiors and selection of appropriate building materials. Architectural solutions determined by the climatic features of these regions are being considered in order to increase energy efficiency and ensure user comfort. Considering that schools belong to the category of buildings with a high level of energy consumption, such as electricity, water and gas, adaptation of architectural design to climatic conditions can significantly reduce energy costs. The article offers an overview of suitable climate-adapted architectural solutions for school buildings in certain regions of Iran, emphasizing the importance of an integrated design approach in the context of modern requirements for energy efficiency and sustainable development.

Exploring the Impact of Urban Morphology on Building Energy Consumption and Outdoor Comfort: A Comparative Study in Hot-Humid Climates

Research simultaneously examining building energy consumption and outdoor thermal comfort within urban environments remains limited. Few studies have delved into the sensitivity of design parameters based on building energy consumption and outdoor thermal comfort. The purpose of this study is to investigate the correlations between urban morphological design parameters and performance indicators, focusing on building energy consumption and outdoor thermal comfort (UTCI), across different urban block layouts in hot-humid regions, like Guangzhou. By establishing six fundamental morphological models—three individual unit layouts and three group layouts—the research explores both control and descriptive parameters through extensive simulation studies. Scatter plot visualizations provide insights into the impacts of various design parameters on energy consumption and UTCI, facilitating a comprehensive analysis of trends and quantitative relationships. Additionally, the study conducts sensitivity analyses on design parameters under different layout conditions to highlight their influences on target performance indicators. The findings reveal common trends, such as the significant impacts of plan dimensions and the Floor Area Ratio (FAR) on energy efficiency and outdoor comfort, as well as differential patterns, such as the varying sensitivities of the Shape Factor (S/V) and the Sky View Factor (SVF), across individual and collective layouts. Ultimately, this study offers a nuanced understanding of urban block morphology’s role in creating sustainable, comfortable, and energy-efficient urban environments, providing valuable guidelines for urban form design in hot-humid climates.

Beyond skeletal studies: A computational analysis of nasal airway function in climate adaptation.

Ecogeographic variation in human nasal anatomy has historically been analyzed on skeletal morphology and interpreted in the context of climatic adaptations to respiratory air-conditioning. Only a few studies have analyzed nasal soft tissue morphology, actively involved in air-conditioning physiology. We used in vivo computer tomographic scans of (N = 146) adult individuals from Cambodia, Chile, Russia, and Spain. We conducted (N = 438) airflow simulations during inspiration using computational fluid dynamics to analyze the air-conditioning capacities of the nasal soft tissue in the inflow, functional, and outflow tract, under three different environmental conditions: cold-dry; hot-dry; and hot-humid. We performed statistical comparisons between populations and sexes. Subjects from hot-humid regions showed significantly lower air-conditioning capacities than subjects from colder regions in all the three conditions, specifically within the isthmus region in the inflow tract, and the anterior part of the internal functional tract. Posterior to the functional tract, no differences were detected. No differences between sexes were found in any of the tracts and under any of the conditions. Our statistical analyses support models of climatic adaptations of anterior nasal soft tissue morphology that fit with, and complement, previous research on dry skulls. However, our results challenge a morpho-functional model that attributes air-conditioning capacities exclusively to the functional tract located within the nasal cavity. Instead, our findings support studies that have suggested that both, the external nose and the intra-facial soft tissue airways contribute to efficiently warming and humidifying air during inspiration. This supports functional interpretations in modern midfacial variation and evolution.

Evaluation of three suction pretreatment systems for the air compressor

Air compressor, as the power source of pneumatic tools, suffers the problems of low efficiency and high failure rate in summer. In this paper, three suction air pretreatment systems are presented, which are characterized by the cold sources: a vapor compression refrigeration unit, a water chilling unit and a combination of water chilling unit with cooling tower. Models for the thermodynamic and economic performance evaluation of the three systems are established and solved. The moisture diffusion coefficient is applied to consider the influence of the moisture condensation and the Marshall and Swift coefficients is introduced to consider the capital change over time. Formula to calculate the efficiency of refrigeration compressor is adopted. Besides, the system total efficiency, percentage of power saving (PPS) and payback period (PBP) are defined as performance indexes. A comparative study with typical meteorological data of hot-dry regions and hot-humid regions is conducted to analyze the superiority of each system under the operation conditions of varied suction air temperature and volume flow. According to the results, optimal spray water flowrate exists for each operation condition and an air–water ratio of 0.8 is recommended. When the suction air temperature decreases, the PBP of each system increases and a sharp increase occurs when the temperature is lower than the air dew point temperature. A suction air temperature of 26 ℃ is suggested. Direct air cooling with an evaporator is preferred when the suction air volume flowrate is smaller than 60 m3/min for hot-humidity regions. The combined system is significantly superior in hot-dry regions. The PBP of the three systems is all longer than 10 months. How to guarantee the usage rate is the key for enterprises to consider the use of suction air pretreatment systems.

Feasibility Analysis of Indirect Evaporative Cooling System Assisted by Liquid Desiccant for Data Centers in Hot-Humid Regions

The rapid development of data centers (DCs) has led to a marked increase in energy consumption in recent years, which poses a direct challenge to global efforts aimed at reducing carbon emissions. In regions with hot and humid climates, the energy demand is largely driven by air conditioning systems necessarily to maintain appropriate operational temperatures. This study proposes a novel multi-stage indirect evaporative cooling (IEC) system, incorporating a liquid desiccant in the primary air channel to address the cooling demands of such DCs. Our approach involves a two-stage process where the first stage uses a liquid desiccant-based IEC (LD-IEC) for air dehumidification and the second stage utilizes the treated air from the first stage as the secondary air to enhance the cooling effect. A simulation model of the proposed system is established with validation, and the performance of the multi-stage system was also discussed based on different operation modes. Furthermore, a case study was conducted to investigate the feasibility of using this system in the DC under a typical hot and humid zone. The findings reveal that the first-stage LD-IEC is capable of diminishing the wet-bulb temperature of the ambient air. Furthermore, the case study demonstrates that the proposed system can greatly improve the temperature drop by 72.7% compared to the single IEC, which noticeably reduces the operation time of energy-intensive supplementary cooling equipment from 5092 h to 31 h given the supply air temperature threshold of 25 °C. In summary, the proposed system could substantially decrease reliance on traditional cooling systems, which demonstrates a promising avenue to fully use this passive cooling technology for cooling DCs.

Numerical study on heat transfer characteristics of spray cooling double skin façade

Using spray cooling technology to solve the overheating issue in double skin façade (DSF) is an important attempt to reduce building energy consumption. While, the thermal performance of the spray cooling double skin façade (SC-DSF) is not very clear, especially the complicated heat transfer characteristics. In this study, a comprehensive numerical model of SC-DSF system including solar radiation and two-phase flow problem is established by using three-dimensional steady Euler-Lagrange method to analyze the heat transfer characteristics from a microscopic perspective. And the CFD model is validated by the experiment. Meanwhile, a quantitative analysis is conducted to investigate the thermodynamic and kinetic behavior of the SC-DSF in hot humid climate region in China. The influences of outdoor air relative humidity, solar radiation intensity, and outdoor wind speed on the water spray cooling effect of the DSF are analyzed. The cooling efficiency of SC-DSF system is sensitive to the outdoor relative humidity. In a sufficiently cooled condition, the minimum temperature in the cavity is close to the outdoor wet-bulb temperature. The spray cooling efficiency reaches 28.2 % with the outdoor relative humidity of 20 %, but decreases to only 9.3 % as relative humidity rises to 80 %. Outdoor wind speed also has some impact on the spray cooling system, an optimal outdoor wind speed of 1.5 m/s can enhance cooling efficiency by 6.6 %, but it has adverse effect on the cooling efficiency when wind speed exceeds 3 m/s. However, in addition to increasing surface temperature of the DSF, solar radiation has little influence on the cooling performance. Excessive humidity exceeding 80 % and wind speed surpassing 3 m/s may render the spray system ineffective. Therefore, the effects of environmental conditions should be fully considered and utilized in the design and application of spray cooling systems.

Performance analysis of a novel two-bed adsorption humidification-dehumidification desalination system using Metal-organic framework 801

Adsorption desalination techniques have been increasingly studied over the last century as a sustainable option for meeting the rapidly growing demand for fresh water. One of the attractive factors for using adsorption desalination systems is the use of low-grade thermal energy normally wasted in the atmosphere. The current study introduces a novel adsorption desalination system integrated with a humidification dehumidification system for producing potable water. Four system configurations are presented. The main distinction between them is the source of hot water used for the humidifier. Scheme #1 utilizes the heat of condensation, Scheme #2 applies the heat of condensation plus the heat of adsorption, while Scheme # 3 adds the outlet of heating water from the desorber as a source of heat to the humidifier. Scheme #4 is a standalone adsorption desalination system that applies chilled water to cool the condenser. The novelty of this system is the application of the chilled water from the evaporator to the dehumidifier to create the highest possible temperature difference necessary for the humidification and dehumidification process. This advantage allows larger water productivity, especially in hot humid regions. In this case, it is possible to extract water vapour in the ambient humid air, water vapour gained from the humidification process and water vapour condensed in the condenser of the adsorption desalination system. Moreover, we have used a novel material Metal Organic Frameworks 801 as an adsorbent for a highly efficient process. Based on the results, Scheme #3 produced the maximum amount of fresh water, 210 kg/h while Scheme #2 obtained the maximum gained output ratio, 4.4 with a minimum cost of 0.0079 $/L. A standalone adsorption system produced the minimum amount of distillate water and the lowest gained output ratio. It is not advisable to use a standalone adsorption system to produce distillate water; as the full desalination potential is not achieved.

Thermal insulation material produced from recycled materials for building applications: cellulose and rice husk-based material

Construction materials derived from agro-industrial waste are increasingly attractive in the building sector, due to their sustainability and lower environmental impact. Hence, in recent years worldwide the amount of research and publications tending to the development of materials that take advantage of residues from agro-industrial activities has increased. The role of thermal insultation materials in the building envelope is significant, especially in hot-humid region. This study presents the manufacturing and evaluation of a cellulose and rice husk-based insulation material, as a proposal for the reuse of materials considered as value-added waste, such as recycled paper and rice husks. Boards and test specimens were elaborated, as well as mechanical and thermal tests. The material was evaluated by means of thermal tests, in accordance with ASTM C177, to measure the thermal conductivity. Tensile and compressive strength tests were performed, based on ASTM C209 and ASTM C39 Standard, respectively. According to the results obtained, the material shows a thermal coefficient of 0.04 W/m∙K which corresponds to a material with the potential to thermally insulate an enclosure. Maximum stresses were obtained for the 3 compositions in average for a range between 1.31 and 1.76 MPa. Ultimate compressive strength obtained was between 20.19 and 21.23 MPa. The proposed material is presented as a sustainable alternative, which can be used in the field of environmentally friendly buildings, which contribute to reducing the carbon footprint, by energy savings.

Global genetic diversity, introgression, and evolutionary adaptation of indicine cattle revealed by whole genome sequencing

Indicine cattle, also referred to as zebu (Bos taurus indicus), play a central role in pastoral communities across a wide range of agro-ecosystems, from extremely hot semiarid regions to hot humid tropical regions. However, their adaptive genetic changes following their dispersal into East Asia from the Indian subcontinent have remained poorly documented. Here, we characterize their global genetic diversity using high-quality whole-genome sequencing data from 354 indicine cattle of 57 breeds/populations, including major indicine phylogeographic groups worldwide. We reveal their probable migration into East Asia was along a coastal route rather than inland routes and we detected introgression from other bovine species. Genomic regions carrying morphology-, immune-, and heat-tolerance-related genes underwent divergent selection according to Asian agro-ecologies. We identify distinct sets of loci that contain promising candidate variants for adaptation to hot semi-arid and hot humid tropical ecosystems. Our results indicate that the rapid and successful adaptation of East Asian indicine cattle to hot humid environments was promoted by localized introgression from banteng and/or gaur. Our findings provide insights into the history and environmental adaptation of indicine cattle.

Elderly residents’ uses of fragmented outdoor spaces in public housing estates in Hong Kong——Decoding causality and heat-risk exposure

Well-designed open/semi-open spaces in public housing estates (PHEs) are important urban living rooms for urban residents to enhance well-beings, relieve from cramped homes, and cope with hotter climate. In order to understand the elderly residents' space use in light of space/neighbourhood attributes and microclimates, mobile field tests including physical measurement, passive observation, and questionnaire survey were carried out in 33 fragmented outdoor spaces (FOSs) in Choi Hung Estate (CHE) and Upper Ngau Tou Kok Estate (UNTKE) in Hong Kong from June to early October 2022. GIS application was adopted to map the vitality in association with microclimates. The ordered probit model and multilevel regression model were employed to explore the contributions of factors to the elderly's FOSs use. It is shown that the time of the day, microclimate (mPET—modified PET for hot-humid regions & wind speed), FOSs attributes (SVF, nature view, functionality, size), and neighbourhood attributes (accessibility & building density) significantly influence elderly attendance in FOSs. One degree increase in mPET is associated with around 4.7% decrease in the elderly's FOSs use. The elderly is likely exposed to unconscious heat risks under the compensatory effects of space and neighbourhood building attributes on the thermal environment of a FOS, and popular FOSs contribute to an increase in heat tolerance by approximately 5 °C in terms of mPET. A FOS that maintains mPET between 30.8 °C and 33.1 °C in summer, along with other favourable attributes (SVF, accessibility & functionality) may help mitigate the heat risks and increase overall usage rate.

The Multi-Objective Optimization Design and Hydrothermal Performance Evaluation of Anhydrous Calcium Sulfate Whisker and Polyester Fiber Compound Modified Asphalt Mixture in Hot-Humid Areas.

In hot and humid climates, asphalt pavements frequently encounter environmental factors such as elevated temperatures and rainfall, leading to rutting deformations and potholes, which can affect pavement performance. The primary objective of this study was to enhance the hydrothermal characteristics of asphalt mixtures through an investigation into the impact of anhydrous calcium sulfate whisker (ACSW) and polyester fiber (PF) on the hydrothermal properties of asphalt mixtures. In this paper, a central composite concatenation design (CCC) was employed to determine the optimal combination of ACSW and PF contents, as well as the asphalt aggregate ratio (AAR). Each influencing factor was assigned three levels for analysis. The evaluation indexes included dynamic stability, retained Marshall stability, and tensile strength ratio. Using the analysis methods of variance and gray correlation degree analysis, the hydrothermal properties of the asphalt mixture were examined in relation to the contents of ACSW, PF, and AAR based on the CCC results. Consequently, the optimal mix design parameters for composite modified asphalt mixture incorporating ACSW and PF were determined. The results indicated that the asphalt mixtures with hydrothermal qualities exhibited optimal performance in terms of 4.1% ARR, 11.84% ACSW, and 0.4% PF. The interaction between AAR and ACSW content had a greater effect on the dynamic stability and tensile strength ratio of the asphalt mixture, whereas the incorporation of ACSW and PF had a greater effect on the retained Marshall stability of the asphalt mixture. Among the three contributing factors, AAR exhibited the strongest relationship with the hydrothermal characteristics of the asphalt mixture, followed by the ACSW content; the correlation of PF content was the lowest. Therefore, to enhance the hydrothermal characteristics of the asphalt mixture, it is important to conduct a full evaluation of the constituents of ACSW and PF, along with the AAR in hot-humid regions.

Examining the Effects of Tree Canopy Coverage on Human Thermal Comfort and Heat Dynamics in Courtyards: A Case Study in Hot-Humid Regions

Providing thermal comfort in the courtyards of academic buildings is important and increasing tree canopy coverage (TCC) presents a convenient and feasible method to achieve this; however, few studies have comprehensively evaluated the cooling effects of TCC, considering both outdoor thermal comfort and heat dynamics. In this study, we selected two typical academic buildings at Guangzhou University, each with courtyards having different height-to-width ratios (H/W ratios). We employed both field measurements and ENVI-met-based numerical models to simulate scenarios with varying TCCs. The results demonstrated that the cooling effects caused by arranging trees increase with the TCC values. During the hottest hours of the day, trees arranged in courtyards with high H/W ratios exhibited a superior cooling effect compared to those in courtyards with low H/W ratios, with a difference of up to 0.6 °C in the PET (physiological equivalent temperature); however, over the entire daytime, the total sensible heat reduction achieved by trees in courtyards with low H/W ratios surpassed that of courtyards with high H/W ratios, with a difference of up to 0.25 × 104 J/m2. Our findings underscore the crucial role of TCC in enhancing cooling in the courtyard of academic buildings, with important implications for university planning and design.

Performance prediction and optimization of cross-flow indirect evaporative cooler by regression model based on response surface methodology

In recent years, indirect evaporative cooling has rapidly developed with high-accuracy numerical models. As the application of this technology expands from hot-arid areas to hot-humid regions, there is still a lack of regression models of the cross-flow indirect evaporative cooler (IEC) that can be used in different climate regions. Regression models can not only improve prediction efficiency but also be helpful for engineering design. In this study, the regression models of the cross-flow IEC were established based on the response surface methodology (RSM). Eight essential factors, including the inlet air properties, geometric size, and operating parameters, were determined as the input factors, while five indicators were selected as the output responses. The central composite design was employed to generate the matrix for the RSM-based model, and the matrix response data were obtained from an established numerical IEC model validated by the experimental results. The effects of the single and interactive factors are analyzed for each response. Furthermore, the developed models are evaluated by comparing the anticipated results with the on-site measurement data in a real project, and then the multi-objective optimization is conducted for the prediction of IEC performances in five typical cities of China. In summary, the regression models can forecast the cross-flow IEC in a more straightforward approach, which may also assist the design and optimization.