Hot-humid Regions Research Articles

Techno-economic evaluation and environmental benefit of hybrid evaporative cooling system in hot-humid regions

Reducing the energy consumption of buildings is of great importance to achieve carbon neutrality targets. The air conditioning (AC) system in buildings, as a large energy consumer, should be taken into account as one of the main building service systems for energy saving integrated with energy-efficient and environmental-friendly technologies. Indirect evaporative cooler (IEC), constrained by its cooling principle, originally exerts energy saving potential in hot-arid regions. Recently, progress has been made in expanding its application to hot-humid regions. However, due to the large cooling load in hot-humid regions, an IEC-integrated hybrid system should be developed as an improved solution to effectively save energy and maintain the indoor thermal comfort. In view of the lack of a complete hybrid IEC system being reported thus far, in this study, the IEC is combined with a cooling coil unit as a primary air handling unit (IEC-PAU) for fresh air handling and supply. Accordingly, the model of the IEC-PAU with indoor fan coil units (FCUs) is constructed and incorporated into a typical office building, and the results are compared with a baseline case under hot-humid climate conditions. Comprehensive energy, economic, and environmental benefits are analyzed considering different setpoint temperatures in typical cities of the Great Bay area (GBA) of China. Results show that the proposed system could reduce the energy consumption of 4.6 kWh/m2 on average, with the acceptable thermal comfort level as they are in the reference cases. The greatest energy saving ratio is 8.3%, while the performance of the proposed system declines under the higher setpoint temperature. The saved electricity expenses can lead to the average discounted payback period of 8.2 years in the GBA cities. Furthermore, an annual greenhouse gas emission of 4.8 t on average can be diminished. In summary, this work demonstrates the feasibility of the hybrid IEC system as an effective approach for energy saving in hot-humid regions, which is promising to prompt the carbon neutrality in China.

Low-temperature solar thermal-power systems for residential electricity supply under various seasonal and climate conditions

In this work, the performance of low-temperature (<100 °C) solar thermal-power systems to satisfy residential electric loads was analyzed. The solar-driven system was designed to provide a fraction of the total electricity demand in a complementary operation with the electric grid. The analysis was conducted for an coperation during seven days each season, considering real solar and climate variables and residential loads at different climate zones in the United States. The efficiency of the system strongly depends on the solar radiation profile and the ambient temperature. Maximum efficiencies of around 9.5% were obtained in the cold and marine climate zones due to the high solar energy input and low heat dissipation temperatures. In these two zones, the system could supply more than 98% of the electricity demand all seasons. At mixed-humid and hot-humid regions, the system supplied around 50% of the electric load in three of the four seasons, but it only supplies about 27% of the electricity needs in the mixed-humid zone during summer and hot-humid zone during winter. The effect of the solar collector field area and the tank volume was also analyzed. In general, larger solar fields positively impact the efficiency. However, the impact of the tank volume varies depending on the solar radiation profile and the load requirements. Average efficiencies for the seven-day operation can be larger than 6% with a proper selection of the solar collector area and tank volume for an Organic Rankine Cycle with a capacity of about 2.6 kW. Finally, an economic analysis of the system was conducted, and the results were compared with a solar PV + battery system of similar capacity. It is expected that the cost for the analyzed solar-thermal system decreases in the coming years with the increased interest on low temperature applications.

Hygrothermal performance optimization of lightweight steel-framed wall assemblies in hot–humid regions using orthogonal experimental design and a validated simulation model

As a layered construction, lightweight steel-framed (LSF) wall assemblies are applicable to different climates and used worldwide. Due to ill-informed construction and material designs, moisture-related durability problems occur, especially in hot–humid areas. Here, a hygrothermal simulation model of typical LSF wall assemblies was validated, and the influences of six construction layers (each with three sets of parameters) on the overall properties and performance were investigated via orthogonal experimental design (OED). Each layer exhibited various impact trends and contribution ratios at different positions. To reduce moisture risks, LSF wall assemblies should generally prevent the infiltration of outdoor moisture as much as possible while strengthening the inward drying capacity. The optimal configuration should comprise multiple water and vapour barriers with a ventilated layer, external insulation, permeable cavity insulation and interior sheathing board with a finish. Finally, this optimization method comprising the hygrothermal simulation and OED techniques could be applied to the hygrothermal performance of LSF wall assemblies under certain climatic conditions.

Impact of coupled heat and moisture transfer on indoor comfort and energy demand for residential buildings in hot-humid regions

Moisture significantly affects indoor thermal comfort and energy demand. However, the coupled heat and moisture transfer (HAMT) effect inside the wall assemblies is often ignored in building performance calculations. To quantify its impact on building performance under hot and humid climates, the thermal environment and energy demand of an apartment in Guangzhou (China) were evaluated with and without HAMT finite element algorithm, respectively. The HAMT effects are quantified and analyzed in different periods. Different boundary conditions regarding climate uncertainty, wind-driven rain effect, and wall solar absorptance are considered. The results show that under naturally ventilated conditions, ignoring the effect of HAMT in walls can lead to an overestimation of indoor operative temperature by 1.2 °C in summer and an underestimation of 1.7 °C in winter. The deviation in indoor operative temperature calculated by the two models is noticeable from noon to midnight. On the other hand, cooling and dehumidification demand energy demand can be underestimated by 8.4% and 12.4%, respectively, without consideration of HAMT. The HAMT also increases the probability of high hourly energy demand for cooling and dehumidification under the HAMT effect. These findings emphasize the importance of considering the HAMT effect when evaluating building performance in hot and humid regions.

Experimental investigations on thermal performance of spray cooling double skin façade in hot humid climate region

Thermal performance of the spray cooling double skin façade in hot and humid climate region are experimentally investigated in this study. Two identical double skin facades are constructed for the comparative analysis. Thermal performance of the spray cooling double skin façade is evaluated by the indicators of cavity air temperature, glass surface temperature, the U-value, and solar heat gain coefficient. The influences of the ventilation mode (open conditions of the top and bottom vents in the double skin façade system), operation time (spray and interval time of the spray system), and spray direction on the cooling effect of the spray cooling double skin façade are experimentally compared and analyzed, and the operation mode of the spray cooling double skin façade with the best thermal performance is obtained. The results demonstrate that the appropriate operation mode of the spray cooling double skin façade is that the top and bottom vents are opened, and the spray direction is from up to down with the operation time of 10/15 min (spray/interval time). The average temperature of the cavity and inner glass decreased by 8.1 °C and 3.7 °C, respectively. The mean U-value and SHGC of the spray cooling double skin façade are 2.13 W/(m2·K) and 0.25, respectively, which are smaller than the most stringent limit values of the current national standard. The spray cooling double skin façade has good thermal performance in hot humid climate region in China.

Developing methodology to assess the thermal comfort of traditional Malay house

The natural harmony between people, houses, and the environment is frequently highlighted in studies on traditional architecture. Traditional Malay house architecture, for example, is designed in hot-humid regions to promote maximum thermal comfort with natural ventilation while minimizing dampness. However, further research is required to determine if the traditional house is a sustainable design that can still adapt to current climate conditions due to global warming’s increased indoor environment. This paper intends to identify and discuss the thermal comfort assessment approach by implement empirical research through field measurement. The assessment involves physical measurements and a satisfaction survey—the data analysis using a statistical adaptive model, computer simulation, and comparative analysis. Lastly, the data is verified based on the ASHRAE Standard 55 and hypothesis-testing. The finding will contribute to aiding the stakeholders and designers to adapt the traditional Malay house construction as an example of the best or alternative designs of climate-responsive architecture. Thus, the idea of producing a climate-responsive recommend simulation research.

Energy and exergy simulation analysis and comparative study of solar ejector cooling system using TRNSYS for two climates of Iran

This paper addresses hourly simulation of 3.5 kW Solar Ejector Cooling System (SECS) using R600a and R290 hydrocarbon refrigerants for application in two office buildings in semi-arid and hot-humid climates of Iran. During the period of the study, thermodynamics energy and exergy of the cooling systems when charged with the two refrigerants are fully assessed by simulation at the two study sites. The simulation studies of the entire cooling system indicate that the most irreversible process and hence the prime exergy destruction is related to the solar collector system followed by the ejector component in the cooling cycle. The ejector is a constant-area mixing (CAM) type which is mathematically modeled in Engineering Equation Solver (EES) software. Generator of the cooling cycle is modeled in EES using ε−NTU method and a simulation program is developed on TRNSYS-EES co-simulator for dynamic study of the cooling cycle. For comparison of efficiency of the two refrigerants, working conditions are set to be the same. The systems are equipped with auxiliary heaters to provide constant inlet temperature of 85C∘ for the generator when solar radiation is partially in phase with the building sites. The hourly and monthly simulation of both SECS in June, July, August and September 2019 demonstrate that R290 is more efficient for increasing the overall COP(=0.2844) of the system than R600a (COP=0.2797) of the building office in the semi-arid region where the generator receives most of its thermal energy from solar radiation in July 17, 2019. Although, the same refrigerant is also more efficient than R600a in the hot-humid region system in the same day, but the system compensates shortage of its necessary solar thermal energy mostly from the auxiliary heater.

Thermal Environment and Energy Performance of a Typical Classroom Building in a Hot-Humid Region: A Case Study in Guangzhou, China

Buildings and the construction sector account substantially for global energy consumption. In hot-humid areas of China, suboptimal thermal comfort in classrooms has heightened their cooling load and energy consumption. It is necessary to renovate the buildings of outdated code according to the current weather conditions to save energy. This study thus aimed to examine the thermal effects of such designs on the cooling load, based on an actual classroom building during summers in hot-humid southern China. Using air temperature and PMV values to evaluate thermal comfort, this study conducted simulation through EnergyPlus and DesignBuilder. The resultant updated typical meteorological year (TMY) and the monthly and hourly analyses of indoor thermal comfort revealed persistent classroom overheating. To mitigate the cooling load, numerous design variables were investigated: space form, roofing, external walls, windows, and shading devices. Evaluative comparisons found that appropriate choice of external windows and shading devices represented the two most effective strategies in mitigating the cooling load. Furthermore, jointly applying effective retrofit strategies to the building yielded a favorable reduction in the annual cooling energy consumption by 16.6%. The findings herein are envisioned to provide evidence-based referential guidance for building designs for classrooms in a hot-humid climate.

Sustainable active cooling strategies in hot and humid climates – A review and a practical application in Somalia

Providing spaces with thermal comfort is a critical need, particularly in hot-humid regions, where more than a third of the world's population are settled. In terms of space cooling technologies, the global market is largely dominated by window air conditioners and ductless mini-splits. However, numerous other options are available and require more exploration to clearly identify their advantages against conventional systems. In this regard, there are plenty of studies about active cooling systems, but still little is known about the best choices for their application in high-density buildings in extreme humid climates, where latent loads are dominant. In such a framework, this paper briefly examines and identifies possible solutions for space cooling in non-residential buildings in hot-humid climates. In this sense, an all-air system with heat recovery and a radiant ceiling coupled with air handling were identified as the most recommended options for such environments, based on their working principles. Furthermore, the study includes a detailed assessment of the application of these solutions on a case-study building in Mogadishu, Somalia, from the point of view of the cooling demand to the energy consumption of the selected cooling systems. The findings of this work can be extrapolated to be then applied in other developing cities, and outline the path future research should follow to improve the systems.

A Solution-Processed Inorganic Emitter with High Spectral Selectivity for Efficient Subambient Radiative Cooling in Hot Humid Climates.

Daytime radiative cooling provides an eco-friendly solution to space cooling with zero energy consumption. Despite significant advances, most state-of-the-art radiative coolers show broadband infrared emission with low spectral selectivity, which limits their cooling temperatures, especially in hot humid regions. Here, an all-inorganic narrowband emitter comprising a solution-derived SiOx Ny layer sandwiched between a reflective substrate and a self-assembly monolayer of SiO2 microspheres is reported. It shows a high and diffusive solar reflectance (96.4%) and strong infrared-selective emittance (94.6%) with superior spectral selectivity (1.46). Remarkable subambient cooling of up to 5°C in autumn and 2.5°C in summer are achieved under high humidity without any solar shading or convection cover at noontime in a subtropical coastal city, Hong Kong. Owing to the all-inorganic hydrophobic structure, the emitter shows outstanding resistance to ultraviolet and water in long-term durability tests. The scalable-solution-based fabrication renders this stable high-performance emitter promising for large-scale deployment in various climates.

Study on wind environment of semi-open space in hot-arid and hot-humid climate zones in rural areas

To explore the coupling effect of open space temperature and air velocity in hot-arid and hot-humid climate regions in rural China, 1690 valid data were obtained by long-term field tests and questionnaires were carried out in hot-arid and hot-humid regions. Results indicated that when the operative temperature is below 33.5 °C, the mean thermal sensation decreases with the increase of air velocity in the hot-humid region. When the operative temperature rose to greater than 33.5 °C, the mean thermal sensation could be significantly reduced only when the air velocity is over 1.0 m/s. However, increasing air velocity in hot-arid regions can significantly improve the thermal sensation. In addition, residents in hot-humid regions were more willing to increase airflow than those in hot-arid regions. These results support the theory of climate adaptation and can provide a reference for the design of semi-open space buildings in rural regions.

Enhancing Indoor Thermal Comfort and Energy Efficiency in Residential Buildings of Hot Humid Region of Nepal – A Case of Biratnagar Metropolitan City

Enhancing Indoor Thermal Comfort and Energy Efficiency in Residential Buildings of Hot Humid Region of Nepal – A Case of Biratnagar Metropolitan City

Analysis of H2O/EMISE absorption chiller driven by stationary solar collectors in hot-humid climate

The performance of H2O/EMISE (1-ethyl-3-methylimidazolium ethyl sulfate) absorption chiller driven by stationary solar collectors including the flat plate collector (FPC), evacuated tube collector (ETC), compound parabolic collector (CPC) in hot-humid climate is the focus of this study. As a case study, the cooling capacity of the absorption chiller is constant at 100 kW and used for air conditioning in Guangzhou, China with the inlet/outlet temperature of cooling water fixed at 32/37 °C and the inlet/outlet temperature of chilled water set at 17/12 °C. The effects of heat source temperature between 78 and 100 °C on the thermodynamic as well as economic performance of the solar absorption chiller system have been analyzed and meanwhile the application potentials of the three candidate solar collectors are compared also. The results show that there is an optimum heat source temperature makes the coefficient of performance (COP) and exergetic efficiency (ECOP) of solar absorption chiller system maximum, which is featured with a shifting to lower values compared to the optimum one that leads to the COP of absorption chiller machine maximum. Besides, while the CPC absorption chiller system has the best thermodynamic performance with the overall COP and ECOP about 0.351 and 0.027, respectively, the ETC system becomes the most economic one with the specific investment cost about 1194 USD/kW. Recommendations are given based on the findings as resources to help the design of solar driven H2O/EMISE absorption chiller systems in the hot-humid region.

Crystalline Silicon (c-Si) Solar Cell Interconnect Damage Prediction Function Based on Effect of Temperature Ramps and Dwells on Creep Damage under Field Thermal Cycling

c-Si solar cell interconnection damages from thermal cycles emanate from cumulative damage contributions from the various load steps in a typical thermal cycle. In general, a typical thermal cycle involves five thermal load steps, namely: 1st cold dwell, ramp-up, hot dwell, ramp-down, and 2nd cold dwell. To predict the contributions of each of these load steps to creep damage in soldered interconnections, each of the respective load steps needs to be profiled to accurately fit a function capable of predicting the damage contributions from a given number of thermal cycles. In this study, a field thermal cycle profile generated from in situ thermal cyclings at a test site in Kumasi, a hot humid region of sub-Saharan Africa, is used to predict damage in solar cell interconnections from accumulated creep energy density using finite element analysis (FEA). The damage was assessed for two different solder formulations, namely: Pb60Sn40 and Sn3.8Ag0.7Cu (lead-free). The results from the FEA simulations show that the cooling (ramp-down) load steps accounted for the highest accumulated creep energy density (ACED) damage in solder interconnections. The ramp-up load steps followed this closely. The cumulative contributions of the two load steps accounted for 78% and 88% of the total damage per cycle in the Pb60Sn40 and Sn3.8Ag0.7Cu solder interconnections, respectively. Furthermore, a study of the damage profiles from each of the five load steps revealed that each of the damage functions from the various load steps is a step function involving the first two thermal cycles, on one hand, and the remaining 10 thermal cycles on the other hand. The damage from the first two thermal cycles can be predicted from a logarithmic function, whereas the damage from the remaining 10 thermal cycles is predicted using six-order polynomial functions. The ACED results computed from the damage functions are in close agreement with the results from the FEA simulation. The functions generated provide useful relations for the prediction of the life (number of cycles to failure) of solder interconnections in solar cells. The systematic approach used in this study can be repeated for other test sites to generate damage functions for the prediction of the life of c-Si PV cells with SnPb and lead-free solder interconnections.

Dynamic Simulation of Desiccant Cooling System with Simultaneously Using Solar and Ground Renewable Energies in Hot-Humid Regions

This paper presents the dynamic operation of a desiccant cooling system combined with solar and ground source energies. Solar energy is used for providing the required energy for regenerating the desiccant wheel, and the ground source heat exchanger is exploited as an air pre-cooling component. The potential of the system in providing thermal comfort is assessed in hot-humid regions. Results reveal that this system is capable of providing thermal comfort in these regions with low-grade regeneration temperatures (lower than 75 ℃). As a new perspective, the maximum value of the desiccant wheel regeneration temperature is controlled. The effect of the desiccant wheel performance and its maximum regeneration temperature is evaluated on the behavior of the system. With results, high performance desiccant wheel increases the provided thermal comfort up to 40% and the contribution of solar energy up to 14% compared with its low performance. Reducing the maximum regeneration temperature to 50 ℃, decreases the achieved thermal comfort to lower than 30%. Ground source heat exchanger enhances the thermal comfort and a specified level of that can be provided with lower regeneration temperatures. The economical assessment shows that in entirely provided thermal comfort conditions by the system, the payback period is calculated to be 8.2 years.

Influence of permeability ratio on wind-driven ventilation and cooling load of mid-rise buildings

Natural ventilation potential in terraced buildings is affected by numerous parameters such as permeability ratio, distribution pattern, depth of terraces, etc. This research aims to evaluate the impact of permeability ratio on natural ventilation potential and cooling load of a terraced office building in the hot- humid climate. To this end, one solid block and eight porous models with different permeability ratios (20 %–30 %–40 %–50 %) and random distribution patterns were simulated and analyzed by Energyplus engine and computational fluid dynamics (CFD). For better comparison, two distribution patterns for each permeability ratio were simulated. CFD simulations were validated according to the wind-tunnel measurements. The cooling load amount, mean and maximum airspeed as well as the mean age of air in terraces and offices were used to evaluate the best configurations of porous buildings.The results show that increasing the permeability up to 50 % will enhance the interior and inlet airspeed by 38.59 % and 49.07 % compared to the solid case. Simulations proved that a small change in porosities from 20 % to 30 % resulted in a significant difference in mean and maximum airspeed in terraces. The case with 50 % permeability ratio indicated higher values of mean and maximum airspeed in terraces. The mean age of air amount follows a descending process from the permeability ratio of 0–30 % and then increases gradually. The 30 % porous model with 30.8 s mean age of air is considered as the best case.According to the results, the introduction of permeability does not leave a positive effect on cooling energy demand despite natural ventilation performance. Although porosity reduces the solar radiation heat gain and increases the natural ventilation potential, porous models indicated high values of cooling energy consumption. This is due to the high amount of exposed surface area in porous models which leads to an increase of cooling energy demand up to 2.7 % compared to the solid case.As a result, among the permeable models, the best natural ventilation performance and the lowest cooling energy consumption are attributed to 50 % and 20 % permeable groups respectively.This study helps the designers to better understand the ventilation and energy performance of a porous model and to improve the energy-efficient buildings in hot-humid regions.

Investigation on the Temperature Distribution of Asphalt Overlay on the Existing Cement Concrete Pavement in Hot-Humid Climate in Southern China

Temperature is known to be one of the most important factors affecting the design and performance of asphalt concrete pavement. The distresses of asphalt overlay are closely related to its temperature, particularly in Guangxi, a hot-humid-climate region in China. This research is to analyze the impact of meteorological factors on temperature at 2 cm depth in asphalt overlay by ReliefF algorithm and also obtain the temperature prediction model using MATLAB. Two test sites were installed to monitor the temperatures at different pavement depths from 2014 to 2016; meanwhile, the meteorological data (including air temperature, solar radiation, wind speed, and relative humidity) were collected from the two meteorological stations. It has been found that the temperature at 2 cm depth experiences greater temperature variation, and the maximum and minimum temperatures of asphalt overlay, respectively, occur at 2 cm depth and on the surface. Besides, the results of ReliefF algorithm have also shown that the temperature at 2 cm depth is affected significantly by solar radiation, air temperature, wind speed, and the relative humidity. Based on these analyses, the prediction model of maximum temperature at 2 cm depth is developed using statistical regression. Moreover, the data collected in 2017 are used to validate the accuracy of the model. Compared with the existing models, the developed model was confirmed to be more effective for temperature prediction in hot-humid region. In addition, the analysis of rutting depth and overlay deformation for the two test sections with different materials is done, and the results have shown that reasonable structure and materials of asphalt overlay are vital to promote the high-temperature antideforming capability of pavement.

Assessing the hygrothermal performance of typical lightweight steel-framed wall assemblies in hot-humid climate regions by monitoring and numerical analysis

Lightweight steel-framed (LSF) construction has attracted interest and gained popularity worldwide in recent years; however, due to a lack of knowledge, LSF construction suffers from premature failure related to moisture problems in hot-humid regions. To assess the risk of durability failure in developing LSF assemblies, four typical LSF wall assemblies fabricated with two kinds of construction methods were monitored for 10 months under real environmental conditions in the typical hot-humid city of Guangzhou. Wall assembly can become wet when the weather is wet or the indoor environment is air conditioned. Wall assemblies with a ventilatable cladding system (Wall C) are the least susceptible to wetness, followed by assemblies with a ventilatable cladding system and external extruded polystyrene (XPS) board (Wall A), assemblies with stucco cladding (Wall D) and assemblies with stucco cladding and external XPS board (Wall B). Wall A performs the best in terms of mold growth and corrosion risk, while Wall B and Wall D have the highest risks with regard to mold growth and corrosion, respectively. However, the LSF components could reduce the time of wetness (TOW) on the surface of the external sheeting (insulation) board. The external XPS board could significantly reduce the TOW in the structural cavity, while the stucco cladding system leads to a higher moisture risk. Special attention should be given to the sealing quality of the edges, especially at the bottom, and at the interface between the stucco cladding and external insulation, as these locations have the greatest risk of moisture problems.

On the Comparison of Thermal Comfort Performances in Dutch Style Churches with Low Ventilation in Hot-Humid Tropical Region

Colonized by the Dutch for a hundred years, Indonesia has many Dutch-style churches in its cities. The uniqueness of the churches is that they have low ventilation in the below part of side-by-side walls to penetrate air movement in buildings. This current research was conducted on two Dutch-style churches with different heights of low ventilations on their walls. The study aimed to establish correlation modeling between the height of low ventilation and thermal comfort in buildings covering Standard Effective Temperature, Predicted Mean Vote (PMV), and Predicted Percentage Dissatisfied (PPD). The methods used were referred to the ASHRAE Standard 55-2017 and statistically analyzed by using linear regression and Anova of SPSS 24. The measurements were performed at the same three devotional times at similar multiple specified measuring points inside the churches. The results showed that the church with 40 cm height ventilations had 4% higher air velocity than that with 70 cm height ventilations. For PMV, the church with 40 cm height low ventilation has a 'neutral' sensation, while the one with 70 cm height low ventilations has 'slightly cool'. The church with 40 cm height low ventilation has 72% PPD lower significantly than the other.

A Study of the Thermal Environment and Air Quality in Hot–Humid Regions during Running Events in Southern Taiwan

It is quite difficult to investigate thermal comfort in hot–humid regions, and there have not been many real case studies or research related to this issue. In this article, four running events held in nearby popular travel spots in Kaohsiung, the largest city in southern Taiwan, were selected to analyze the influence of thermal environment and air quality on thermal comfort. Mostly real time environmental monitoring data were applied for estimating thermal indicators, along with Sky View Factor (SVF) data taken at the sites of the running scheduled routes, to analyze the thermal performance of participants at running events. Compared with runners, walkers (local residents, fans, and staff of the events) would be exposed to a greater risk of thermal discomfort with increasing time spent on the routes. With the integrated analysis, mPET (modified physiologically equivalent temperature) can be viewed as a relatively comprehensive indicator in considering both environmental thermal conditions and the biometrical differences of activities and clothing types. From the results, a good correlation between mPET and solar radiation/SVF was obtained, which indicated that mPET could be sufficiently sensible in revealing the thermal condition variation from one site to another during the route with time. Based on the discomfort risk assessment, for runners, the event held in autumn with lower SVF at the route sites would be less risky of thermal discomfort, while the event held in spring with lower solar radiation would be more comfortable for walkers. As for air quality condition, the inappropriateness of holding winter outdoor activities in Kaohsiung was obviously shown in both real time monitoring data and long term analysis.