scholarly journals Assessment of the Outdoor Thermal Comfort in Oases Settlements

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 185 ◽  
Author(s):  
Mohamed Elhadi Matallah ◽  
Djamel Alkama ◽  
Atef Ahriz ◽  
Shady Attia
Keyword(s):  
Heat Stress ◽  
Thermal Comfort ◽  
Underground Water ◽  
Outdoor Thermal Comfort ◽  
Water Supplies ◽  
Significant Difference ◽  
The World ◽  
Urban Settlements ◽  
Pet Index ◽  
Oasis Effect

Oases throughout the world have become important ecosystems to replenish food and water supplies. The Saharan Oases exist above the largest underground water supplies in the World. In North Africa, oases witness significantly growing populations in the oasis towns and receive thousands of tourists yearly. In oasis settlements, the majority of the population spends most of the time outdoors, in extremely hot conditions; however, few studies have investigated urban outdoor thermal comfort conditions. Therefore, this study aimed to assess thermal comfort in the Tolga Oasis Complex and test the validity of the ‘oasis effect’ concept. The methodology is based on comparative field measurement and calculation approaches in the heart of Tolga Palm Grove and in different urban settlements. Results indicate highest heat stress levels (Physiologically Equivalent Temperature (PET) index) in the oases Palm Grove in July, PET = 41.7 °C, and urban settlements, PET = 40.9 °C. Despite the significant difference between the old and new settlement fabrics, our measurements and calculation did not identify any noticeable variation of thermal comfort. Thus, the oasis effect on the outdoor thermal comfort was insignificant (during July and August 2018). Finally, the study discusses ways to improve outdoor spaces design and relieve heat stress in the settlements of Tolga.

scholarly journals Biomimicry-Based Strategies for Urban Heat Island Mitigation: A Numerical Case Study under Tropical Climate

Biomimetics ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 48
Author(s):  
Kevin Araque ◽  
Paola Palacios ◽  
Dafni Mora ◽  
Miguel Chen Austin
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Outdoor Thermal Comfort ◽  
Base Case ◽  
Heat Island ◽  
Urban Heat ◽  
Historical Heritage ◽  
Pet Index ◽  
Radiant Temperature

In recent years, demographic growth has caused cities to expand their urban areas, increasing the risk of overheating, creating insurmountable microclimatic conditions within the urban area, which is why studies have been carried out on the urban heat island effect (UHI) and its mitigation. Therefore, this research aims to evaluate the cooling potential in the application of strategies based on biomimicry for the microclimate in a historical heritage city of Panama. For this, three case studies (base case, case 1, and case 2) of outdoor thermal comfort were evaluated, in which the Envi-met software was used to emulate and evaluate the thermal performance of these strategies during March (highest temperature month) and October (rainier month). The strategies used were extracted from the contrast of zebra skin, human skin, evaporative cooling, and ant skin. The results showed a reduction of 2.8 °C in the air temperature at 11:00, the radiant temperature decreased by 2.2 °C, and the PET index managed to reduce the thermal comfort indicator among its categories. The importance of thinking based on biomimicry in sustainable strategies is concluded; although significant changes were obtained, high risks of discomfort persist due to the layout and proximity of the building.

scholarly journals Sea Breeze Front and Outdoor Thermal Comfort during Summer in Northeastern Brazil

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1013
Author(s):  
Max Anjos ◽  
António Lopes ◽  
Andrews José de Lucena ◽  
Francisco Mendonça
Keyword(s):  
Heat Stress ◽  
Thermal Comfort ◽  
Meteorological Data ◽  
Sea Breeze ◽  
Weather Conditions ◽  
Northeastern Brazil ◽  
Outdoor Thermal Comfort ◽  
Physiological Equivalent Temperature ◽  
Local Climate ◽  
Local Climate Zones

Characterizing the behaviour of the sea breeze phenomenon is the foremost factor in the reduction in the heat stress and the achievement of the pleasant environment in coastal cities globally. However, this seminal study shows that the Sea Breeze Front (SBF) development can be related to an increase in outdoor thermal discomfort in a northeastern Brazilian city during summer. We explored the relationship between SBF and thermal comfort conditions using in situ meteorological observations, the SBF identification method, local climate zones (LCZs) classification, and the Physiological Equivalent Temperature (PET) thermal comfort index. SBF days and Non-SBF days were characterized in terms of weather conditions, combining meteorological data and technical bulletins. SBF days included hot and sunny days associated with the centre of the Upper Tropospheric Cyclonic Vortices (UTCV). In contrast, Non-SBF days were observed in UTCV’s periphery because of cloudy sky and rainfall. The results showed that the mean temperature and PET in the SBF days were 2.0 °C and 3.8 °C higher, respectively, compared to Non-SBF days in all LCZ sites. The highest PET, of 40.0 °C, was found on SBF days. Our findings suggest that SBF development could be an aggravating factor for increasing heat stress of the people living in the northeastern coast of the Brazilian city, after SBF passage.

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

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

<p>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.</p><p>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.</p><p>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.</p>

scholarly journals Study on Environment Regulation of Residential in Severe Cold Area of China in Winter: Base on Outdoor Thermal Comfort of the Elderly

2019 ◽  
Vol 11 (22) ◽  
pp. 6509
Author(s):  
Hong Jin ◽  
Bo Wang ◽  
Bingbing Han
Keyword(s):  
Thermal Comfort ◽  
Cfd Simulation ◽  
The Elderly ◽  
Outdoor Thermal Comfort ◽  
Residential Areas ◽  
Physiological Equivalent Temperature ◽  
Climate Conditions ◽  
Outdoor Environments ◽  
Harsh Climate ◽  
Pet Index

Overwhelming evidence shows that the harsh climate conditions are affecting urban residents who are living in severe cold areas of China in winter, particularly affecting the frequency and length of outdoor space usage of the elderly. This study aims (1) to establish the modified model which is suitable for the harsh climate region, (2) to verify whether the physiological equivalent temperature (PET) index can be evaluated for the outdoor thermal comfort of older adults in severe cold areas of China in winter, (3) to draw the thermal comfort map that is based on the former conclusions. In this study, the outdoor environments in typical residential areas for the elderly of Changchun, China, has been investigated by using field measurement, questionnaire survey, and Computational Fluid Dynamics (CFD) simulation. The results show that the wind direction is the important aspects of model modification and quite possibly one of the most neglected. In addition, it is convenient to evaluate outdoor thermal comfort of the elderly on the basis of the PET index and the neutral PET temperature of elderly people who live in severe cold areas of China in winter is −0.5 degrees Celsius. According to the thermal comfort map, the park green land of urban residential is the best area for the elderly.

scholarly journals Impact of climate change on outdoor thermal comfort in cities in united states

2020 ◽  
Vol 158 ◽  
pp. 01002
Author(s):  
Yuqiao Huang ◽  
Dayi Lai ◽  
Yiqing Liu ◽  
Huang Xuan
Keyword(s):  
Climate Change ◽  
United States ◽  
Heat Stress ◽  
Cold Stress ◽  
Thermal Comfort ◽  
The United States ◽  
Stress Rate ◽  
Outdoor Thermal Comfort ◽  
Open Spaces ◽  
Impact Of Climate Change

Since urban open spaces provide various benefits to the citizens, it is necessary to improve the outdoor thermal comfort in urban open spaces. However, global warming increases heat stress and at the same time decrease cold stress of outdoor spaces. The final impact of climate change on outdoor thermal comfort is not evident, and depends on the climate characteristics. This study investigated the influence of climate change on outdoor thermal comfort conditions of five selected cities (Minneapolis, New York City, San Francisco, Miami, and Las Vegas) with distinctive climate patterns in the United States. It is found that all cities suffered from deterioration in thermal comfort. This is because the increases in the heat stress rate were greater than the decreases in cold stress rate. In the 2080s, the greatest reduction in acceptable thermal stress rate happened in Miami from 44.7% to 21.3% under high emission scenario.

scholarly journals Analysis of human thermal comfort in Central European City during summer of 2015: A case of Novi Sad (Serbia)

2020 ◽  
Vol 100 (1) ◽  
pp. 31-39
Author(s):  
Dragan Milosevic ◽  
Stevan Savic ◽  
Danijela Arsenovic ◽  
Zorana Luzanin ◽  
Jelena Dunjic
Keyword(s):  
Heat Stress ◽  
Thermal Comfort ◽  
Extreme Heat ◽  
Outdoor Thermal Comfort ◽  
European City ◽  
Central European ◽  
Human Thermal Comfort ◽  
Local Climate Zones ◽  
Novi Sad ◽  
Extreme Heat Stress

Urban meteorological network (UMN) was established in the Central European City of Novi Sad (Serbia) based on "local climate zones" (LCZs) system. Physiologically Equivalent Temperature (PET) index was used for the assessment of outdoor thermal comfort in the "built" and "land cover" LCZ classes of Novi Sad. The index was calculated in the RayMan software based on the meteorological, physiological as well as building and vegetation data. Temporal analysis was performed for extreme heat stress days (PETmax ? 41 ?C), extreme heat stress hours (PETav ? 41 ?C) and days with occurrence of "tropical nights" (Tmin > 20 ?C) during exceptionally hot summer of 2015. Our results show that extreme heat stress hours are the least frequent in compact midrise LCZ 2, followed by dense trees LCZ A. On the contrary, countryside (low plants - LCZ D) showed to be the most uncomfortable area during daytime followed by compact low-rise areas (LCZ 3). Tropical nights are the most frequent in midrise LCZs 5 and 2 (40-46 nights) and decreasing towards open, sparsely built and natural LCZs (6-8 tropical nights in LCZs A and D). This is almost 800% decrease and it has implications for health and recreation of urban population and emphasizes the need for UMN development based on LCZ system.

scholarly journals Potential Influence of Urban Sprawl and Changing Land Surface Temperature on Outdoor Thermal Comfort in Lagos State, Nigeria

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jerry N. Obiefuna ◽  
Chukwuma J. Okolie ◽  
Peter C. Nwilo ◽  
Olagoke E. Daramola ◽  
Lawrence C. Isiofia
Keyword(s):  
Heat Stress ◽  
Land Cover ◽  
Surface Temperature ◽  
Thermal Comfort ◽  
Land Surface Temperature ◽  
Urban Sprawl ◽  
Land Surface ◽  
Outdoor Thermal Comfort ◽  
Lagos State ◽  
Stress Levels

Abstract The continuous monitoring of the relationship between land surface temperature (LST) and land cover change is imperative for an inquiry into the potential impact of LST on human well-being, including urban outdoor thermal comfort in Lagos State, Nigeria. Using Landsat imagery, this study assessed land cover and LST changes from 1984 to 2019. Land cover was extracted, LST was determined from Landsat imageries and the land cover changes were linked to LST using the contribution index (CI). Afterwards, the universal thermal climate index (UTCI) was calculated to determine the heat stress levels. Findings confirm the presence of urban sprawl and new growth areas in previously rural Local Government Areas (LGAs) eastward, northward and westward of Lagos metropolis and in regions which lie on the fringe of the state's border with Ogun State. Also, a very strong link between high LST intensities and increasing concentration of urban areas in rapidly growing LGAs has been observed. This link further confirms the increased warming of the state, with an increase in mean LST of 2.16°C during 1984–2019. The UTCI which was used to gauge the influence of LST on outdoor thermal comfort ranged from moderate to strong heat stress levels. This study helps to strengthen the case for definite policies and actions which should be aimed at achieving moderate urban development through increased urban tree canopy/green infrastructure provision and carbon sequestration activities in urban design/landscape design, in Lagos State.

scholarly journals Prediction of Climate Change Effect on Outdoor Thermal Comfort in Arid Region

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4730
Author(s):  
Mohamed Elhadi Matallah ◽  
Waqas Ahmed Mahar ◽  
Mushk Bughio ◽  
Djamel Alkama ◽  
Atef Ahriz ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Thermal Comfort ◽  
Weather Conditions ◽  
Extreme Weather ◽  
Simulation Software ◽  
Summer Season ◽  
Outdoor Thermal Comfort ◽  
The Impact

Climate change and expected weather patterns in the long-term threaten the livelihood inside oases settlements in arid lands, particularly under the recurring heat waves during the harsh months. This paper investigates the impact of climate change on the outdoor thermal comfort within a multifamily housing neighborhood that is considered the most common residential archetype in Algerian Sahara, under extreme weather conditions in the summer season, in the long-term. It focuses on assessing the outdoor thermal comfort in the long-term, based on the Perceived Temperature index (PT), using simulation software ENVI-met and calculation model RayMan. Three different stations in situ were conducted and combined with TMY weather datasets for 2020 and the IPCC future projections: A1B, A2, B1 for 2050, and 2080. The results are performed from two different perspectives: to investigate how heat stress evolution undergoes climate change from 2020 till 2080; and for the development of a mathematical algorithm to predict the outdoor thermal comfort values in short-term, medium-term and long-term durations. The results indicate a gradual increase in PT index values, starting from 2020 and progressively elevated to 2080 during the summer season, which refers to an extreme thermal heat-stress level with differences in PT index averages between 2020 and 2050 (+5.9 °C), and 2080 (+7.7 °C), meaning no comfortable thermal stress zone expected during 2080. This study gives urban climate researchers, architects, designers and urban planners several insights into predicted climate circumstances and their impacts on outdoor thermal comfort for the long-term under extreme weather conditions, in order to take preventive measures for the cities’ planning in the arid regions.

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