Evaluation of human thermal comfort and heat stress in an outdoor urban setting in summer under arid climatic conditions

Thermal sensation and heat stress were evaluated in a plastic greenhouse, with and without evaporative cooling, under arid climatic conditions in Riyadh, Saudi Arabia. Suitable thermal comfort and heat stress scales were selected for the evaluation. Experiments were conducted in hot sunny days to measure the required parameters (i.e., the dry and wet bulb temperatures, globe temperature, natural wet bulb temperature, and solar radiation flux) in the greenhouse. The results showed that in the uncooled greenhouse, workers are exposed to strong heat stress and would feel very hot most of the day time; they are safe from heat stress risk and would feel comfortable during night. An efficient evaporative cooling is necessary during the day to reduce heat stress and to improve the comfort conditions and is not necessary at night. In the cooled greenhouse, workers can do any activity: except at around noon they should follow a proposed working schedule, in which the different types of work were scheduled along the daytimes based on the heat stress value. To avoid heat stress and to provide comfort conditions in the greenhouses, the optimum ranges of relative humidity and air temperature are 48–55% and 24–28°C, respectively.

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Evaporative Cooling Options for Building Air-Conditioning: A Comprehensive Study for Climatic Conditions of Multan (Pakistan)

Energies ◽

10.3390/en13123061 ◽

2020 ◽

Vol 13 (12) ◽

pp. 3061 ◽

Cited By ~ 3

Author(s):

Shazia Noor ◽

Hadeed Ashraf ◽

Muhammad Sultan ◽

Zahid Mahmood Khan

Keyword(s):

Thermal Comfort ◽

Co2 Emissions ◽

Air Conditioning ◽

Evaporative Cooling ◽

Cooling Capacity ◽

Climatic Conditions ◽

Maximum Temperature ◽

Human Thermal Comfort ◽

Work Input ◽

System Configurations

This study provides comprehensive details of evaporative cooling options for building air-conditioning (AC) in Multan (Pakistan). Standalone evaporative cooling and standalone vapor compression AC (VCAC) systems are commonly used in Pakistan. Therefore, seven AC system configurations comprising of direct evaporative cooling (DEC), indirect evaporative cooling (IEC), VCAC, and their possible combinations, are explored for the climatic conditions of Multan. The study aims to explore the optimum AC system configuration for the building AC from the viewpoints of cooling capacity, system performance, energy consumption, and CO2 emissions. A simulation model was designed in DesignBuilder and simulated using EnergyPlus in order to optimize the applicability of the proposed systems. The standalone VCAC and hybrid IEC-VCAC & IEC-DEC-VCAC system configurations could achieve the desired human thermal comfort. The standalone DEC resulted in a maximum COP of 4.5, whereas, it was 2.1 in case of the hybrid IEC-DEC-VCAC system. The hybrid IEC-DEC-VCAC system achieved maximum temperature gradient (21 °C) and relatively less CO2 emissions as compared to standalone VCAC. In addition, it provided maximum cooling capacity (184 kW for work input of 100 kW), which is 85% higher than the standalone DEC system. Furthermore, it achieved neutral to slightly cool human thermal comfort i.e., 0 to −1 predicted mean vote and 30% of predicted percentage dissatisfied. Thus, the study concludes the hybrid IEC-DEC-VCAC as an optimum configuration for building AC in Multan.

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Future Changes in Human-Biometeorological Index Classes in Three Regions of Luxembourg, Western-Central Europe

Advances in Meteorology ◽

10.1155/2015/323856 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Hanna Leona Lokys ◽

Jürgen Junk ◽

Andreas Krein

Keyword(s):

Climate Change ◽

Heat Stress ◽

Thermal Stress ◽

Thermal Comfort ◽

Central Europe ◽

Spatial Resolution ◽

Climate Index ◽

Human Thermal Comfort ◽

Air Temperatures ◽

The Impact

Projected climate change will cause increasing air temperatures affecting human thermal comfort. In the highly populated areas of Western-Central Europe a large population will be exposed to these changes. In particular Luxembourg—with its dense population and the large cross-border commuter flows—is vulnerable to changing thermal stress. Based on climate change projections we assessed the impact of climate change on human thermal comfort over the next century using two common human-biometeorological indices, the Physiological Equivalent Temperature and the Universal Thermal Climate Index. To account for uncertainties, we used a multimodel ensemble of 12 transient simulations (1971–2098) with a spatial resolution of 25 km. In addition, the regional differences were analysed by a single regional climate model run with a spatial resolution of 1.3 km. For the future, trends in air temperature, vapour pressure, and both human-biometeorological indices could be determined. Cold stress levels will decrease significantly in the near future up to 2050, while the increase in heat stress turns statistically significant in the far future up to 2100. This results in a temporarily reduced overall thermal stress level but further increasing air temperatures will shift the thermal comfort towards heat stress.

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An evaluation of three biometeorological indices for human thermal comfort in urban outdoor areas under real climatic conditions

Building and Environment ◽

10.1016/j.buildenv.2009.11.009 ◽

2010 ◽

Vol 45 (5) ◽

pp. 1346-1352 ◽

Cited By ~ 58

Author(s):

Areti Tseliou ◽

Ioannis X. Tsiros ◽

Spyros Lykoudis ◽

Marialena Nikolopoulou

Keyword(s):

Thermal Comfort ◽

Climatic Conditions ◽

Human Thermal Comfort

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Investigating Applicability of Evaporative Cooling Systems for Thermal Comfort of Poultry Birds in Pakistan

Applied Sciences ◽

10.3390/app10134445 ◽

2020 ◽

Vol 10 (13) ◽

pp. 4445

Author(s):

Hafiz M. U. Raza ◽

Hadeed Ashraf ◽

Khawar Shahzad ◽

Muhammad Sultan ◽

Takahiko Miyazaki ◽

...

Keyword(s):

Heat Stress ◽

Thermal Comfort ◽

Developing Economies ◽

Low Cost ◽

Evaporative Cooling ◽

Ambient Air ◽

Climatic Conditions ◽

Maximum Temperature ◽

Poultry Birds ◽

The City

In the 21st century, the poultry sector is a vital concern for the developing economies including Pakistan. The summer conditions of the city of Multan (Pakistan) are not comfortable for poultry birds. Conventionally, swamp coolers are used in the poultry sheds/houses of the city, which are not efficient enough, whereas compressor-based systems are not economical. Therefore, this study is aimed to explore a low-cost air-conditioning (AC) option from the viewpoint of heat stress in poultry birds. In this regard, the study investigates the applicability of three evaporative cooling (EC) options, i.e., direct EC (DEC), indirect EC (IEC), and Maisotsenko-cycle EC (MEC). Performance of the EC systems is investigated using wet-bulb effectiveness (WBE) for the climatic conditions of Multan. Heat stress is investigated as a function of poultry weight. Thermal comfort of the poultry birds is calculated in terms of temperature-humidity index (THI) corresponding to the ambient and output conditions. The heat production from the poultry birds is calculated using the Pederson model (available in the literature) at various temperatures. The results indicate a maximum temperature gradient of 10.2 °C (MEC system), 9 °C (DEC system), and 6.5 °C (IEC systems) is achieved. However, in the monsoon/rainfall season, the performance of the EC systems is significantly reduced due to higher relative humidity in ambient air.

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Thermal Environment of Urban Schoolyards: Current and Future Design with Respect to Children’s Thermal Comfort

Atmosphere ◽

10.3390/atmos11111144 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1144

Author(s):

Dimitrios Antoniadis ◽

Nikolaos Katsoulas ◽

Dimitris Κ. Papanastasiou

Keyword(s):

Heat Stress ◽

Adverse Effects ◽

Thermal Comfort ◽

Vegetation Cover ◽

Thermal Environment ◽

Positive Impact ◽

High Surface ◽

Well Being ◽

Ambient Conditions ◽

Human Thermal Comfort

Urban outdoor thermal conditions, and its impacts on the health and well-being for the city inhabitants have reached increased attention among biometeorological studies during the last two decades. Children are considered more sensitive and vulnerable to hot ambient conditions compared to adults, and are affected strongly by their thermal environment. One of the urban outdoor environments that children spend almost one third of their school time is the schoolyard. The aims of the present manuscript were to review studies conducted worldwide, in order to present the biophysical characteristics of the typical design of the urban schoolyard. This was done to assess, in terms of bioclimatology, the interactions between the thermal environment and the children’s body, to discuss the adverse effects of thermal environment on children, especially the case of heat stress, and to propose measures that could be applied to improve the thermal environment of schoolyards, focusing on vegetation. Human thermal comfort monitoring tools are mainly developed for adults, thus, further research is needed to adapt them to children. The schemes that are usually followed to design urban schoolyards create conditions that favour the exposure of children to excessive heat, inducing high health risks to them. The literature survey showed that typical urban schoolyard design (i.e., dense surface materials, absence of trees) triggered high surface temperatures (that may exceed 58 °C) and increased absorption of radiative heat load (that may exceed 64 °C in terms of Mean Radiant Temperature) during a clear day with intense solar radiation. Furthermore, vegetation cover has a positive impact on schoolyard’s microclimate, by improving thermal comfort and reducing heat stress perception of children. Design options for urban schoolyards and strategies that can mitigate the adverse effects of heat stress are proposed with focus on vegetation cover that affect positively their thermal environment and improve their aesthetic and functionality.

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What is the most threatening for citizens of a mid-latitude city: cold stress or heat stress?

10.5194/egusphere-egu21-6320 ◽

2021 ◽

Author(s):

Sara Top ◽

Dragan Milošević ◽

Steven Caluwaerts ◽

Stevan Savić

Keyword(s):

Heat Stress ◽

Cold Stress ◽

Thermal Comfort ◽

Heat Wave ◽

Outdoor Thermal Comfort ◽

Belgian Society ◽

Human Thermal Comfort ◽

Summer Heat ◽

Heat And Cold Stress ◽

The City

Both heat and cold waves cause extreme human thermal discomfort and a clear excess in mortality. This shows the importance of knowing the prevailing thermal comfort conditions and how thermal comfort conditions vary in various environments so measures can be taken. Microclimatic and outdoor human thermal comfort conditions are investigated in various built-up and green areas in the city of Ghent (Belgium) using meteorological measurements of six weather stations of the MOCCA (Monitoring the Cities Climate and Atmosphere) network in combination with calculations done by RayMan.Normal to extreme summer heat wave periods show that dangerous strong heat stress prevails during the daytime periods at all locations. Comparison of thermal comfort during normal and extreme summer heat wave periods showed that heat stress is more extreme when a heat wave is more intense. Overall the urban park in Ghent was the most comfortable location during heat waves since it effectively mitigates heat stress in the city. These results should be taken into account in urban planning and design to keep mid-latitude cities livable.Further, a one year data series revealed that outdoor cold stress was more apparent during 2017 in the mid-latitude city of Ghent that experiences a mild maritime climate. During spring and summer, both heat stress and cold stress occurred due to the larger diurnal temperature range compared to the other seasons. Even though high Physiological Equivalent Temperatures (PET) were obtained during a heat wave in summer, heat stress did not occur as intensely and as frequently compared to cold stress on annual level. It could thus be stated that outdoors, cold stress is a bigger threat than heat stress. However, one should keep in mind that the study was executed for outdoor thermal heat comfort and that people will take shelter or take measures when feeling uncomfortable. The question is thus rather, how are citizens protected against heat and cold stress? Currently, the Belgian society is better adapted to cold stress since most buildings contain central heating, while air conditioning is not standard. Future projections predict an increase in temperature, causing more occurrence of extreme heat stress, while extreme cold stress will be reduced. Additionally, the urban heat island effect currently has mainly a positive effect on the average annual outdoor thermal comfort conditions, while it will become a negative effect in the warmer future. Measures should thus be taken to reduce the threat of future heat stress.

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The role of sky view factor and urban street greenery in human thermal comfort and heat stress in a desert climate

Journal of Arid Environments ◽

10.1016/j.jaridenv.2019.04.009 ◽

2019 ◽

Vol 166 ◽

pp. 68-76 ◽

Cited By ~ 15

Author(s):

Armaghan Ahmadi Venhari ◽

Martin Tenpierik ◽

Mohammad Taleghani

Keyword(s):

Heat Stress ◽

Thermal Comfort ◽

View Factor ◽

Urban Street ◽

Human Thermal Comfort ◽

Sky View Factor ◽

Desert Climate

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Use of remote sensing in the identification of Urban Heat Islands and in the evaluation of Human Thermal Comfort

Journal of Hyperspectral Remote Sensing ◽

10.29150/jhrs.v7.7.p408-422 ◽

2018 ◽

Vol 7 (7) ◽

pp. 408

Author(s):

Rafaela Lisboa Costa

Keyword(s):

Remote Sensing ◽

Heat Stress ◽

Surface Temperature ◽

Thermal Comfort ◽

Urban Areas ◽

Satellite Images ◽

Urban Heat Islands ◽

Heat Islands ◽

Human Thermal Comfort ◽

Urban Heat

The objective of this study was to identify heat islands and to evaluate the degree of thermal comfort / discomfort in selected urban areas. Landsat 5 and 8 satellite images were use in the thermal bands and, as a complement, observed data from meteorological stations present in the chosen cities. In order to evaluate heat islands and the degree of thermal comfort / discomfort, the surface temperature was obtain and the Kawamura Discomfort Index (IDK) was use. By means of surface temperature images, it was possible to identify the heat islands in these areas. For IDK, in spite of this index, in general, to present the situation of comfort, for some areas were observe situations of discomfort and heat stress due to the heat, mainly in the year of 2016, considered one of the hottest of this century. The use of observed data was necessary in order to corroborate with the information of the satellites.

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Interrelationships between Land Use Land Cover (LULC) and Human Thermal Comfort (HTC): A Comparative Analysis of Different Spatial Settings

Sustainability ◽

10.3390/su13010382 ◽

2021 ◽

Vol 13 (1) ◽

pp. 382

Author(s):

Lee Bak Yeo ◽

Gabriel Hoh Teck Ling ◽

Mou Leong Tan ◽

Pau Chung Leng

Keyword(s):

Land Use ◽

Heat Stress ◽

Land Cover ◽

Thermal Comfort ◽

Urban Area ◽

Suburban Area ◽

Tropical Region ◽

View Factor ◽

Land Use Land Cover ◽

Human Thermal Comfort

A few studies on outdoor human thermal comfort (HTC) have been conducted in the tropical region in a hot and humid climate; however, there is a paucity of discussions on how exactly different spatial settings influence HTC. Thus, this paper aims to examine how land use land cover (LULC) affects HTC on the basis of the simulation of Predicted Mean Vote (PMV) and Physiologically Equivalent Temperature (PET) indices via ENVI-met and Rayman. The results reveal that people living in the urban area have a higher tendency to experience strong heat stress (25% of the areas with PMV ranging from 3.4 to 3.9 and 2% of the areas, where PMV reached 4.1), followed by the rural area (43% of the areas with PMV ranging from 2.1 to 2.4), and the suburban area (more than 50% of the areas with PMV values less than 2.4). Surprisingly, a concrete LULC in the suburb area exhibits a higher air temperature than an asphalt surface at 4 p.m., due to the large area of high albedo that increases the reflection of solar radiation, subsequently contributing to warming up the airmass. Similarly, sandy, and loamy LULC tend to emit more heat during nighttime, while the heat is absorbed slowly during daytime, and it is then slowly released during nighttime after 6 p.m. Spatial settings that promote heat stress in the urban area are mainly contributed by an LULC of asphalt, concrete, sandy, and loamy areas. Meanwhile, people in the suburban and rural areas are less likely to experience heat stress, due to agricultural plantations and lowland forest that provide shade, except for the barren lands-loamy areas. The result also indicates that tree-covered areas near the river in the suburban area afforded the best thermal experience with PMV of 2.1 and PET of 30.7. From the LULC comparison, it is pivotal to consider tree species (canopy density), surface material (albedo), sky-view factor, wind direction, and speed toward designing a more comfortable and sustainable environment.

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