Ergonomics of the thermal environment. Determination and interpretation of cold stress when using required clothing insulation (IREQ) and local cooling effects

In this study, the authors evaluated clothing insulation and changes in the metabolic rate of individuals in an office environment to determine thermal comfort. Clothing was evaluated using a questionnaire completed by 1306 workers in nine offices. The metabolic rates of 86 workers in three offices were measured using a physical activity meter. The distribution of the temperature at which a person in the room perceived a neutral thermal sensation was then calculated from the determined metabolic rates and clothing insulation values. The results demonstrate a noticeable difference between the average and most frequent values during the summer. Moreover, the required temperature distribution is not normal; rather, it is broad and skewed to the low-temperature side. Therefore, even if a thermally uniform environment is provided at the average required temperature by preventing temporal and spatial variations in the thermal environment, complaints of an unacceptably hot thermal environment are more likely to occur than complaints of an excessively cold thermal environment.

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Quantifying the Effects of Urban Form on Land Surface Temperature in Subtropical High-Density Urban Areas Using Machine Learning

Remote Sensing ◽

10.3390/rs11080959 ◽

2019 ◽

Vol 11 (8) ◽

pp. 959 ◽

Cited By ~ 12

Author(s):

Yanwei Sun ◽

Chao Gao ◽

Jialin Li ◽

Run Wang ◽

Jian Liu

Keyword(s):

Surface Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

Urban Form ◽

Urban Areas ◽

Thermal Environment ◽

High Density ◽

Cooling Effects ◽

Urban Thermal Environment ◽

The Impact

It is widely acknowledged that urban form significantly affects urban thermal environment, which is a key element to adapt and mitigate extreme high temperature weather in high-density urban areas. However, few studies have discussed the impact of physical urban form features on the land surface temperature (LST) from a perspective of comprehensive urban spatial structures. This study used the ordinary least-squares regression (OLS) and random forest regression (RF) to distinguish the relative contributions of urban form metrics on LST at three observation scales. Results of this study indicate that more than 90% of the LST variations were explained by selected urban form metrics using RF. Effects of the magnitude and direction of urban form metrics on LST varied with the changes of seasons and observation scales. Overall, building morphology and urban ecological infrastructure had dominant effects on LST variations in high-density urban centers. Urban green space and water bodies demonstrated stronger cooling effects, especially in summer. Building density (BD) exhibited significant positive effects on LST, whereas the floor area ratio (FAR) showed a negative influence on LST. The results can be applied to investigate and implement urban thermal environment mitigation planning for city managers and planners.

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A Numerical Study on Mitigation Strategies of Urban Heat Islands in a Tropical Megacity: A Case Study in Kaohsiung City, Taiwan

Sustainability ◽

10.3390/su12103952 ◽

2020 ◽

Vol 12 (10) ◽

pp. 3952 ◽

Cited By ~ 2

Author(s):

Jou-Man Huang ◽

Liang-Chun Chen

Keyword(s):

Thermal Environment ◽

Numerical Study ◽

Mitigation Strategies ◽

Comfort Level ◽

Tropical Region ◽

Permeable Pavement ◽

Coverage Ratio ◽

Urban Heat ◽

Cooling Effects

In recent years, with the rapid increase in global warming and urbanization, urban heat island effects (UHI) have become an important environmental issue. Taiwan is no exception, with previous studies demonstrating serious UHIs in megacities. Although existing UHI research has utilized computer simulations to analyze improvement scenarios, there are few cooling strategy studies in actual blocks of Taiwan. Therefore, this study selected a block of a megacity in a tropical region of Taiwan as a case study by ENVI-met. Five improvement strategies were tested and compared to the current situation (B0): (1) Case C1 changed to permeable pavement, (2) Case C2 increased the green coverage ratio (GCR) of the street to 60%, (3) Case C3 changed to permeable pavement and increased the GCR in the street to 60%, (4) Case C4 changed to permeable pavement, increased the GCR in the street to 60%, and increased the GCR in the parks to 80%, and (5) Case C5 changed to permeable pavement, increased GCR in the street to 60% and parks to 80%, and set the GCR on the roof of public buildings to 100%. The results showed that the average temperature of the current thermal environment is 36.0 °C, with the comfort level described as very hot. Among the five improvement schemes, C5 had the greatest effect, cooling the area by an average of 2.00 °C. Further analysis of the relationship between the different GCRs of streets (SGCR) and the cooling effects revealed that for every 10% increase in the SGCR, the temperature of the pedestrian layer was reduced by 0.15 °C.

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Thermophysiological Comfort of Surgeons and Patient in an Operating Room Based on PMV-PPD and PHS Indexes

Applied Sciences ◽

10.3390/app10051801 ◽

2020 ◽

Vol 10 (5) ◽

pp. 1801 ◽

Cited By ~ 2

Author(s):

Radostina A. Angelova ◽

Rositsa Velichkova

Keyword(s):

At Risk ◽

Relative Humidity ◽

Operating Room ◽

Air Temperature ◽

Indoor Environment ◽

Thermal Environment ◽

Climatic Conditions ◽

Clothing Insulation ◽

Indoor Thermal Environment ◽

Predicted Heat Strain

There are different actors in an operating room (OR), who have controversial requirements for the indoor thermal environment. While the patient is at risk of perioperative hypothermia, the surgeons are in a state of thermophysiological discomfort. The study presents an analysis of the thermophysiological comfort of both patient and surgeons in an OR. Surgical clothing ensembles with three values of clothing insulation are simulated. Different indoor environment conditions (air temperature and relative humidity) are tested. The analysis is based on the calculation of predicted mean vote and predicted percentage of dissatisfied (PMV-PPD) indexes and assessment of the climatic conditions categories. Discussion of the predicted heat strain is also presented. The simulated results and their analysis show considerable discrepancies between the thermophysiological comfort of the patient and the surgeons, even when dressed in a light protective ensemble, in the same indoor environment.

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Analyzing the Effect of Water Body on the Thermal Environment and Comfort at Indoor and Outdoor Spaces in Tropical University Campus

International Journal of Environmental Science and Development ◽

10.18178/ijesd.2021.12.10.1352 ◽

2021 ◽

Vol 12 (10) ◽

pp. 282-288

Author(s):

Farhadur Reza ◽

◽

Shoichi Kojima ◽

Wataru Ando

Keyword(s):

Thermal Comfort ◽

Thermal Environment ◽

Outdoor Thermal Comfort ◽

University Campus ◽

Clothing Insulation ◽

Comfort Index ◽

Outdoor Spaces ◽

Globe Temperature ◽

And Performance ◽

University Spaces

Water bodies play a significant role in its surrounding thermal environment. Thermal comfort in university spaces is critical that affects the students’ health and performance as well as the staffs. This study investigated thermal environment and comfort near lakeside and non-lakeside tropical university spaces. Standard Effective Temperature (SET*) have been calculated using recorded air temperature, relative humidity, globe temperature, air velocity, clothing insulation and metabolic rate to evaluate the thermal comfort in outdoor and indoor spaces. The effects of weather parameters have been clearly visible on the comfort index. The calculated SET* values indicate that the outdoor thermal comfort near a lake is much closer to the standard comfort zone than non-lakeside outdoor space. In the case of indoor thermal comfort, however, slightly a different scenario has been observed. To achieve the desirable indoor thermal environment, some design considerations are recommended based on findings.

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Human-Oriented Design of an Indoor Thermal Environment

E3S Web of Conferences ◽

10.1051/e3sconf/201911102001 ◽

2019 ◽

Vol 111 ◽

pp. 02001

Author(s):

Masanari Ukai ◽

Tatsuo Nobe

Keyword(s):

Air Conditioning ◽

Thermal Environment ◽

Thermal Sensation ◽

Hot Spot ◽

Clothing Insulation ◽

Air Conditioning System ◽

Indoor Thermal Environment ◽

Initial Survey ◽

Air Conditioning Systems ◽

Temperature Side

In this study, an initial survey of clothing insulation and changes in the metabolic rate of individuals in office spaces was performed to establish the distribution of room temperatures at which individuals perceived a neutral thermal sensation. Subsequently, the indoor thermal environment in four offices was surveyed during the summer with different air-conditioning systems to determine the thermal environment stability in each case. The results revealed that for the required temperature, there was a noticeable difference between the average and most frequent values. Moreover, it was determined that the required temperature distribution is not normal, but rather, it is skewed to the low-temperature side. In addition, the radiant air-conditioning system was found to generate a narrow distribution of the equivalent temperature and hence, facilitated a more uniform thermal environment compared to a convective (multi-unit) air-conditioning system. Therefore, in buildings with convective air-conditioning systems, even if the planar average thermal environment is categorized as comfortable, it may be possible that workers who are sensitive to the cold or heat will complain of discomfort more frequently than those in buildings with radiant air-conditioning systems because the probability of workers sitting in cold- or hot-spot areas is higher in the former case.

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Field Study on Human Thermal Adaptation in Summer of Tibetan Dwellings in Kangding, China

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.737.169 ◽

2015 ◽

Vol 737 ◽

pp. 169-172

Author(s):

Xiao Ji Song ◽

Wu Xing Zheng ◽

Quan He ◽

Yi Mei Ren

Keyword(s):

Thermal Environment ◽

Thermal Sensation ◽

Thermal Adaptation ◽

Outdoor Temperature ◽

Indoor Temperature ◽

Clothing Insulation ◽

Preferred Temperature ◽

Change Rate ◽

Neutral Temperature ◽

Environment Parameters

In order to study the human thermal adaptation in Tibetan dwellings of Kangding Tibetan Autonomous Prefecture, Sichuan Province, selected 4 dwellings in Tagong and Zhonggu village as the research objects and used the method of objective thermal environment parameters test combined with the subjective questionnaire, and got a total of 119 valid samples, the data analysis results show that indoor air temperature in this area was low, average clothing insulation was 0.75clo and it correlated with outdoor temperature was stronger than that with indoor temperature. The change rate of human thermal sensation changing along with outdoor temperature was 0.113 per temperature and it was 0.147 per temperature changing along with indoor temperature. Thermal neutral temperature was 18.5°C and preferred temperature was 20.65°C, neutral temperature was lower than preferred temperature but closer to average indoor temperature (17.36°C).

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Interactions of mild hypothermia and hypoxia on finger vasoreactivity to local cold stress

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00103.2019 ◽

2019 ◽

Vol 317 (3) ◽

pp. R418-R431 ◽

Cited By ~ 3

Author(s):

Michail E. Keramidas ◽

Roger Kölegård ◽

Igor B. Mekjavic ◽

Ola Eiken

Keyword(s):

Cold Stress ◽

Thermal State ◽

Mild Hypothermia ◽

Thermal Sensation ◽

Interactive Effects ◽

Whole Body ◽

Affective Valence ◽

Local Cooling ◽

Air Exposure ◽

Cold Provocation

We examined the interactive effects of mild hypothermia and hypoxia on finger vasoreactivity to local cold stress. Eight male lowlanders performed, in a counterbalanced order, a normoxic and a hypoxic (partial pressure of oxygen: ~12 kPa) hand cold provocation (consisting of a 30-min immersion in 8°C water), while immersed to the chest either in 21°C [cold trials; 0.5°C fall in rectal temperature (Trec) from individual preimmersion values], or in 35.5°C water, or while exposed to 27°C air. The duration of the trials was kept constant in each breathing condition. Physiological (Trec, skin temperature, cutaneous vascular conductance, oxygen uptake) and perceptual (thermal sensation and comfort, local pain, affective valence) reactions were monitored continually. Hypoxia accelerated the drop in Trec by ~14 min ( P = 0.06, d = 0.67). In the air-exposure trials, hypoxia did not alter finger perfusion during the local cooling, whereas it impaired the finger rewarming response following the cooling ( P < 0.01). During the 35.5°C immersion, the finger vasomotor tone was enhanced, especially in hypoxia ( P = 0.01). Mild hypothermia aggravated finger vasoconstriction instigated by local cooling ( P < 0.01), but the response did not differ between the two breathing conditions ( P > 0.05). Hypoxia tended to attenuate the sensation of coldness ( P = 0.10, r = 0.40) and thermal discomfort ( P = 0.09, r = 0.46) in the immersed hand. Both in normoxia and hypoxia, the whole body thermal state dictates the cutaneous vasomotor reactivity to localized cold stimulus.

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Simulating Human Physiological Response with a Thermal Manikin Testing Different Non Active Medical Devices

Materials Science Forum ◽

10.4028/www.scientific.net/msf.636-637.36 ◽

2010 ◽

Vol 636-637 ◽

pp. 36-40 ◽

Cited By ~ 2

Author(s):

Iara Braga ◽

M. José Abreu ◽

F.M. Duarte

Keyword(s):

Medical Device ◽

Thermal Insulation ◽

Thermal Environment ◽

Objective Evaluation ◽

Thermal Manikin ◽

Clothing Insulation ◽

Temperature Development ◽

Surgical Gown ◽

Surgical Gowns ◽

Selection Of

The thermal insulation of a clothing system represents a quantitative assessment of the way cloth provides thermal barrier to the user. One of this clothing systems, the surgical gown used in the operating theatre, is considered as a non-active medical device and obeys the Medical Device Directive 93/43/EEC. New materials and gowns are being developed, fitting the level of the barrier function with the comfort issues and therefore the selection of the most suitable gown is vital. During the last 60 years, thermal manikins have been used to measure clothing insulation and to assess the thermal environment regarding comfort issues. The main goal of the present study is the comparison of the thermal insulation values during the objective evaluation using the dry thermal manikin with the results obtained using an Infra-Red camera ThermaCAM, monitoring the temperature development of different surgical gowns at a constant skin temperature of 33 °C in neutral environmental conditions.

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