Thermal Sensation Scale Research Articles

Effect of Wind Velocity on Clothing Thermal Resistance and Indoor Comfortable Temperature Design

In this paper, it uses a manikin to test effect of wind velocity on the surface of clothing thermal resistance, and concludes that with the increase of wind velocity, the heat resistance of the clothing decrease rapidly. A seven-point thermal sensation scale was used to evaluate thermal sensation in Tianjin area, the result shows that the neutral temperature is 27.2 °C when the wind velocity is 0.82 m/s . Above 3.2°C is higher than the current specification recommended indoor temperature 24°C. It shows an appropriate increase indoor air velocity can improve the building comfortable temperature. Saving energy 29.7％一41.6％.So provides an effective way reducing the energy consumption of the air conditioning system.

The influence of trees and grass on outdoor thermal comfort in a hot‐arid environment

AbstractThe effects of vegetation on human thermal stress in a hot‐arid region were tested in two semi‐enclosed urban spaces with various combinations of mature trees, grass, overhead shading mesh and paving. The index of thermal stress was calculated hourly from measured meteorological data in the studied sites to evaluate thermal comfort in the different spaces based on radiative and convective pedestrian–environment energy exchanges and sweat efficiency, and expressed on a thermal sensation scale ranging from ‘comfortable’ to ‘very hot’. The efficiency of water use in providing improved comfort was gauged for each of the vegetative landscaping treatments by comparing the total evapotranspiration with the reduction in thermal stress, both expressed in terms of their values in equivalent energy. While conditions in a paved, unshaded courtyard were found to be uncomfortable throughout the daytime hours (with half of these hours defined by severe discomfort), each of the landscape treatments made a clear contribution to improved thermal comfort. With shading, either by trees or mesh, discomfort was reduced in duration by over half and limited in maximum severity when the shading was placed above paving. When combined with grass, both shading mechanisms yielded comfortable conditions at all hours. In both cases, the effect of trees was more pronounced than that of the mesh, but by a small margin. With unshaded grass, ‘hot’ conditions in the courtyard were restricted to a short period in mid‐afternoon, a considerable improvement over unshaded paving, attributable mainly to the lower radiant surface temperatures. Copyright © 2010 Royal Meteorological Society

EFFECTS ON INSTALLING AIR-CONDITIONERS INTO PUBLIC ELEMENTARY AND JUNIOR HIGH SCHOOLS ALL TOGETHER

This paper discussed the influence on the thermal environment in classrooms and the learning attitude and health of the students by installing air-conditioners into classrooms of public elementary schools and junior high schools. The main results are as follows;1) More than 50% of the students and teachers in the schools answered that thermal environment of air-conditioned classrooms were “comfort”. More than 50% of the students answered “neutral” on thermal sensation scale. On the contrary, more than 40% of the teachers chose the answer “slightly hot” in the seven schools.2) The occupants in the classrooms were able to concentrate on studying with the aid of air-conditioners. Most of the teachers answered the positive effect on students' learning attitude by the air-conditioners.3) Most of them showed a positive view of installing air-conditioners into classrooms.

A new predictive index for evaluating both thermal sensation and thermal response of the human body

About 20 years ago, Ring and de Dear [Ring JW, de Dear R. Temperature transients: A model for heat diffusion through the skin, thermoreceptor response and thermal sensation. Indoor Air 1991; 1(4):448–56] introduced a thermal response index ( R) for evaluating the cutaneous thermoreceptor response and thermal sensation. Although the mentioned index possesses the advantages of simplicity and sensitivity, it has not been commonly used over the years. The main reason for this infrequent using is that the mentioned index is not in conformity with the ASHRAE standard thermal sensation scale. To remedy this deficiency we try to present a new predictive index by finding a relationship between the thermal response index ( R) and ASHRAE thermal sensation scale. In the present study, a new thermal response index, TRESP, is introduced on the basis of Ring and de Dear model. The TRESP index has been verified by extensive comparisons with the published analytical and experimental results where a good agreement was found under both steady-state and transient conditions. Results indicate that the new index can accurately predict the thermal sensation with average absolute errors of 0.19 and 0.28 under steady-state and transient conditions, respectively.

Effects of Sleep Deprivation on Perceptual Responses to Multiple Bouts of Acute Cold Exposure Recovery

While the physiological responses to acute cold exposure (ACE) have been examined, little research has been conducted evaluating the recovery (ACE-REC) from ACE during the presence of an additional stressor such as sleep deprivation (SDEP). Further, multiple bouts of ACE over 53 hours of sleep deprivation may elicit a differential response in thermal sensation as compared to a single bout of ACE. Currently limited research exists that has examined the perceptual responses during re-warming following multiple bouts of ACE-REC during SDEP. PURPOSE: To examine the effects of 53 hours of SDEP on the perceptual responses during ACE-REC from three consecutive bouts of ACE. METHODS: Eight healthy, Caucasian males (22.8 ± 1.7 y) completed a control (CON) trial during a normal night's sleep and an experimental trial during 53 hours of SDEP in which they were exposed to cold air (10°C) for 120-min, once per day, for 3 consecutive days (ACE-REC stage 1, 2, 3) followed by 120-min of ACE-REC 25°C air. During ACE-REC, thermal sensation (TS), and modified thermal sensation (MTS) were examined at baseline (BASE), 5-min, 15-min and every 15-min thereafter for the duration of the ACE-REC. RESULTS: Condition by time repeated measures ANOVAs demonstrated a main effect for time (p< 0.001) TS and MTS for all stages of ACE-REC. MTS decreased across time while TS increased across time. CONCLUSION: Based on these data participants sensed and scaled a decreased perception of cold. The presence of SDEP or multiple bouts of ACE may have altered the perception of the participants and their ability to scale thermal sensation. The response demonstrated by both thermal sensation scales may be attributed to fatigue or a mismatch between sensory and physiological responses based on previous data whereby rectal temperature decreased across time while skin temperature increased across time. While the Gagge and Modified Gagge thermal sensation scales are a valid method of assessment during ACE, further investigation is warranted in the area of thermal sensation and perception of cold during ACE-REC during SDEP.

Assessment of Thermal Comfort: A Study at Closed and Ventilated Call Centre

Problem statement: The aims of study were to investigate the effects of environmental factors including the human physiology and thermal comfort during the cycle of process works in workplace. Approach: The selected production line was handling the restoration of trouble report. The environment examined was the relative humidity (%), wind speed (m sec −1 ), illuminance (lux) and air temperature (°C) of the surrounding workstation area. The environmental factors were measured using thermal comfort apparatus, which is capable to measure simultaneously those mentioned environmental factors. The time series data of fluctuating level of factors were plotted to identify the significant changes of factors. Then the thermal comfort of the workers was assessed by using ISO Standard 7730 and thermal sensation scale by using Predicted Mean Vote (PMV). Further Predicted Percentage Dissatisfied (PPD) is used to estimate the thermal comfort satisfaction of the occupant. Finally the PMV were plotted to present the thermal comfort scenario of workers involved in related workstation. Results: The thermal comfort assessment of this workplace which is slightly warm following by thermal sensation and likely to be dissatisfied by the occupant. Conclusion: The result indicated that the activity level and clothing more influenced comfort to the occupants.

Linguistic dimensions in descriptors expressing thermal sensation in Korean: ‘warm’ projects thermal comfort

The present study was triggered by the inconsistency in verbal descriptors in English and Korean describing 'warm' and 'hot' in the thermal sensation scale. The purpose of this study was to examine the linguistic dimensions of the terms expressing 'ttatteuhada (warm)' and 'yakkan duptta (slightly hot)' in Korean. A total of 988 urban Koreans (479 males and 509 females) participated in a questionnaire survey consisting of six questions. The one-to-one survey was conducted indoors in December 2008. Our results showed that (1) 'warm' and 'slightly hot' in Korean are distinctive thermal descriptors; (2) 'warm' projects thermal comfort (80.4% of 988 respondents), but 'slightly hot' projects some thermal discomfort (54.3% of 988 respondents); (3) a slight thermally comfortable feeling was expressed as 'warm' (83.9% of 988 respondents), while a slight thermally uncomfortable feeling was seldom expressed as 'warm' (6.2% of 988 respondents) in mild heat environments; (4) the linguistic dimension within the term 'warm' was less affected by individual thermal susceptibility (vulnerability) than that of the term 'slightly hot'. In summary, 'warm' in Korean connotes a thermally comfortable feeling. In the case of being a little thermally uncomfortable, Koreans project their thermal sensation through the term 'slightly hot', rather than 'warm'. In conclusion, thermal descriptors in the ISO 10551/ASHRAE scale, i.e., 'very cold-cold-cool-slightly cool-neutral-slightly warm-warm-hot-very hot', are not valid for the evaluation of mild hot environments in Korea. A new categorical scale is required in Korean considering the descriptors 'warm' and 'slightly hot'.

The Use of Mixed-Method, Part-Body Pre-Cooling Procedures for Team-Sport Athletes Training in the Heat

The current study investigated the effects of a pre-cooling intervention on physiological and performance responses to team-sport training in the heat. Seven male lacrosse players performed a familiarization session and 2 randomized, counterbalanced sessions consisting of a 30-minute intermittent-sprint conditioning session. Prior to the sessions, players performed a 20-minute mixed-method, part-body cooling intervention (consisting of cooling vests, cold towels to the neck, and ice packs to the quadriceps) or no cooling intervention. Performance was determined from collection of 1 Hz global positioning system (GPS) data and analyzed for distance and speed. Prior to, during, and following the sessions, core temperature, heart rate, rating of perceived exertion (RPE), and thermal sensation scale (TSS) were measured; additionally, a venous blood sample was collected before and after each session for measurement of interleukin-6 (IL-6), insulin-like growth factor (IGF-1) and insulin-like growth factor-binding protein3 (IGF-BP3). Results indicated that a greater distance was covered during the pre-cooling condition (3.35 +/- 0.20 vs. 3.11 +/- 0.13 km; p = 0.05). Further, most of this improvement was evident from a greater distance covered during moderate intensities of 7 to 14 km/h (2.28 +/- 0.18 vs. 2.00 +/- 0.24 km; p = 0.05). Peak speeds and very-high-intensity efforts (20 km/h +/-) were not different between conditions (p > 0.05). The increase in core temperature was blunted following cooling, with a lower core temperature throughout the cooling session (38.8 +/- 0.3 vs. 39.3 +/- 0.4 degrees C; p < 0.05). However, there were no differences in heart rate, RPE, TSS, IL-6, IGF-1, or IGF-BP3 between conditions (p > 0.05). Accordingly, the use of a mixed-method, part-body cooling intervention prior to an intermittent-sprint training session in the heat can assist in reducing thermoregulatory load and improve aspects of training performance for team sports.

Indoor thermal conditions and thermal comfort in air-conditioned domestic buildings in the dry-desert climate of Kuwait

The summer season in the state of Kuwait is long with a mean daily maximum temperature of 45 °C. Domestic air conditioning is generally deployed from the beginning of April to the end of October. This accounts for around 75% of Kuwaiti electrical power consumption. In terms of energy conservation, increasing the thermostat temperature by 1 °C could save about 10% of space cooling energy [1,2]. However, knowledge of indoor domestic temperatures and thermal comfort sensations is important to aid future advice formulation and policy-making related to domestic energy consumption. A field study was therefore conducted during the summers of 2006 and 2007 to investigate the indoor climate and occupants' thermal comfort in 25 air-conditioned domestic buildings in Kuwait. The paper presents statistical data about the indoor environmental conditions in Kuwait domestic residences, together with an analysis of domestic-occupant thermal comfort sensations. With respect to the latter, a total of 111 participants provided 111 sets of physical measurements together with subjective information via questionnaires that were used to collect the data. By using linear regression analysis of responses on the ASHRAE-seven-point thermal sensation scale, the neutral operative temperatures based on Actual Mean Vote (AMV) and Predicted Mean Vote (PMV) were found to be 25.2 °C and 23.3 °C, respectively, in the summer season. Findings from this study provide information about the indoor domestic thermal environment in Kuwait, together with occupant thermal comfort sensations. This knowledge can contribute towards the development of future energy-related design codes for Kuwait.

Thermal Comfort Assessment: A Case Study at Malaysian Automotive Industry

Problem statement: Thermal comfort has a great influence on the productivity and satisfaction of indoor building occupants. The exposure to excessive heat during work may cause discomfort and contributed to low productivity among workers. Malaysia known with its hot and humid weather where in most of the survey study published indicated that workers in Malaysia automotive industries had exposed to excessive temperature while working. The study investigated the thermal comfort level experienced by workers at Malaysian automotive industry. Approach: The study had been conducted at one automotive parts assembly factory in Malaysia. The human subjects for the study constitute operators at tire receiving section of the factory. The environment examined was the relative humidity (%), WBGT, air temperature and radiant temperature (°C) of the surrounding workstation area. The environmental factors were measured using Babuc apparatus, which is capable to measure simultaneously those mentioned environmental factors. The time series data of fluctuating level of factors were plotted to identify the significant changes of factors. Then thermal comfort of the workers was assessed by using ASHRAE thermal sensation scale by using Predicted Mean Vote (PMV). Further Predicted Percentage Dissatisfied (PPD) was used to estimate the thermal comfort satisfaction of the occupant. Finally the PPD versus PMV were plotted to present the thermal comfort scenario of workers involved in related workstation. Results: The trend of relative humidity curve from the graph also indicated the increasing level of discomfort. The radiant temperature observed seems consistent during the study while there was decreasing of WBGT start from afternoon due to the rain. The study revealed that the PPD value of 54% of the workers population at the workstation are likely to be satisfied with thermal comfort at this station while the PMV index from ASHRAE indicated the value 1.07-1.41. Conclusion: The empirical study from the PPD and PMV index indicated that workers working at this were influenced by the heat. The less of PPD value from 80% of the population satisfied with the thermal comfort showed the environment factors that were not good for worker while the PMV index showed the area of work is slightly warm.

Thermal performance study and evaluation of comfort temperatures in vernacular buildings of North-East India

Solar passive techniques are being used in vernacular buildings throughout the world. Researchers have done extensive study on thermal performance of vernacular buildings in the different parts of the world. Vernacular architecture of North-Eastern India represents the principle of climate-responsive architecture, which still lacks experimental validation and quantitative analysis. Thermal comfort not only makes the occupants comfortable but also governs energy consumption in the building. Detailed field studies on thermal performances of typical traditional vernacular dwellings in different bioclimatic zones have been undertaken. This field study includes detailed survey of 150 vernacular dwellings, field tests and thermal sensation vote of 300 occupants on ASHRAE thermal sensation scale. Field test includes measurement of temperature, humidity, illumination level and building design parameters. Thermal performances of these vernacular dwellings were evaluated for winter, pre-summer, summer/monsoon and pre-winter months of the year 2008. This evaluation is based on ‘ adaptive approach’, which is the outcome of the field studies and is now part of ASHRAE standard 55/2004 for predicting comfortable temperature of naturally ventilated buildings. This study also tried to find out the range of comfort temperature in these vernacular buildings for different season of the year. It has been found that these vernacular dwellings perform quite satisfactorily except in the winter months and the occupants feel comfortable in a wider range of temperature.

DIFFERENCE OF THE THERMAL SENSATION VOTES BY THE SCALES IN THE FIELD STUDY OF HOUSES DURING WINTER

The occupants' thermal sensation of the houses was investigated with the three different scales during winter. This paper discussed influence of the thermal sensation scale on the votes. The main results are as follows; 1) eighty eight percent of the occupants responded “acceptable”, despite 70% of the temperature data were out of the comfort range of ASHRAE Standard55, 2) there was a difference in distribution of the votes on each thermal sensation scale, 3) the neutral temperature was 16.3°C (ET*) by one 7-point thermal sensation scale, 9.9°C (ET*) by another scale and 21.2°C (ET*) by linear thermal sensation scale.

Effect of Body Composition on Thermal Sensation During Immersion in 18, 22 and 26°C water

INTRODUCTION: The relation between cold perception (i.e., an individual's ability to sense and scale thermal discomfort) and cold water immersion (CWI) is an area that has considerable practical application to individuals who may be exposed to environmental extremes at work as well as individuals who participate in recreational activities in a wilderness setting. Furthermore, it is well known that body composition plays a role in the regulation of heat exchange and therefore, it is likely that percent fat may subsequently alter thermal sensation (TS). PURPOSE: The goal of the present investigation was to determine if there would be a differential response in TS between low fat (LF: 10.1± 1.4%) vs. high fat (HF: 28.1±3.5%) subjects during immersion in 18, 22 and 26°C water for up to 120 min. METHODS: Six LF males (22.2± 2.0 y) and 5 HF males (23.2± 3.8 y) underwent 3 separate trials during which they were immersed to the first thoracic vertebrae in 18, 22 and 26°C water for up to 120 min (or until rectal temperature < 35°C). The Gagge Thermal Sensation Scale (1967) and the Modified Thermal Sensation Scale (1994) were employed to determine thermal perception during CWI. RESULTS: For both scales, group (LF, HF) x time, repeated measures ANOVA revealed a significant interaction at the 18°C temperature (Gagge, p = 0.049; Modified Gagge p= 0.012) the 22°C temperature (Gagge, p = 0.017; Modified Gagge, p = 0.036), and the 26°C temperature (Modified Gagge, p = 0.018) as LF thermal sensation scores increased at a greater rate than HF subjects. There was a significant main effect for time as thermal sensation scores from both scales increased at all three temperatures (p ≤ 0.001 for all). CONCLUSION: These data illustrate a differential response in thermal perception between LF and HF males across time. This suggests that greater levels of body fat reduced feelings of cold discomfort as immersion time increased during the 18 and 22°C trials.

Measurement Methods of Mean Skin Temperatures for the PMV Model

The predicted mean vote (PMV) model predicts the mean thermal response of a large group of people, according to the ASHRAE thermal sensation scale, and has been proven to agree well with many field studies. However, the model may not predict well the mean response of a small number of people or individuals because it does not take into account the physiological variations of people due to changing thermal environments. In this paper, the thermal comfort sensations of twenty subjects (ten males and ten females) aged 21 to 30 were investigated by Fanger's PMV model. This experimental study found that the PMV model failed to predict the subjects' thermal sensations. The reason may be that the mean skin temperatures (MSTs) of the subjects were fixed uniformly, regardless of the variations of the thermal environments, which results in errors using the PMV model, especially for a small number of subjects. To obtain the MSTs of the subjects under different thermal environments, fourteen measurement methods were employed. Afterwards, the PMV model was used to predict the thermal response of the twenty subjects based on their measured MSTs. The results prove that the prediction accuracy of the PMV model is improved greatly when the MSTs are obtained through measurements instead of theoretical calculations. In addition, this study concludes that the Burton 3-point Method may be the best to measure MSTs for the PMV model.

Physiological Responses to Graded Acute Normobaric Hypoxia Using an Intermittent Walking Protocol

The study aimed to examine the physiological responses to acute normobaric hypoxia during an intermittent walking protocol. Twelve active healthy male participants completed a 125-minute test that involved rest and walking (50% VO(2max)) during normoxic (20.93%O(2)) and 2 hypoxic conditions (14%O(2) and 12%O(2)). A range of physiological markers were measured throughout the test. Lake Louise Questionnaire scores and Environmental Symptoms Questionnaire cerebral scores were used as a measurement of acute mountain sickness symptoms. Oxygen saturation, thermal sensation scale, heart rate, perceived thirst, core temperature, rating of perceived exertion, feeling state, and Deltabody mass all positively correlated with the highest Lake Louise Questionnaire and Environmental Symptoms Questionnaire cerebral scores (P < .05) and were significantly different between the 3 conditions during the exercise phases. A range of physiological markers are associated with symptoms of acute mountain sickness following brief periods of hypoxic exposure.

Effect of Aspirin Ingestion and Fitness Level on Thermal Sensation Following Acute Cold Exposure

INTRODUCTION: The relation between cold perception (i.e., an individual's ability to sense and scale thermal discomfort) following acute cold exposure (ACE) is an area that has considerable practical application to those individuals who may work in cold environments or even those that are recreationally placed in a wilderness setting. Furthermore, it is well known that fitness levels may play a role in thermoregulation and thereby thermal sensation. PURPOSE: Therefore, the goal of the present investigation was to determine if the ingestion of a placebo (PL) vs. a body weight dose of aspirin (1.16 mg.kg-1 body weight) in low fit (LF: VO2 = 36.6 ± 0.9 ml. kg. −1min-1) and high fit (HF: VO2 = 52.0 ± 1.2 ml. kg. −1min-1) males would alter the individual's perception of cold in the recovery phase (i.e., re-warming) following acute cold exposure (ACE-REC). METHODS: Ten males (25.6 ± 1.6 y) underwent pre-experimental testing to determine VO2max and body composition. Subjects underwent 2 trials in which they were required to ingest for one week prior to both trials: a capsule which was filled with cellulose (PL) or, a body weight dose of aspirin (ASA-BW). Each trial consisted of 120 min of exposure to 10oC air (ACE) and 120 min of recovery in 25oC air (ACE-REC). The Gagge Thermal Sensation Scale (1967) vs. the Modified Thermal Sensation Scale (1994) was employed to discern thermal perception at rest during ACE-REC. RESULTS: ANOVA revealed that during ACE-REC the Gagge Scale and the Modified Gagge Scale both demonstrated a main effect for time (p<0.001). However, the Gagge Scale demonstrated a trend for treatment (p=0.056), and a treatment × fitness (LF vs. HF) interaction (p = 0.047). CONCLUSION: From these data it appears that there was a differential response in thermal perception during ACE-REC with respect to treatment × fitness. In addition a trend was demonstrated with respect to treatment via the Gagge Thermal Sensation Scale.

Overall thermal sensation, acceptability and comfort

The relationships between overall thermal sensation, acceptability and comfort were studied experimentally under uniform and non-uniform conditions separately. Thirty subjects participated in the experiment and reported their local thermal sensation of each body part, overall thermal sensation, acceptability and comfort simultaneously. Sensation, acceptability and comfort were found to be correlated closely under uniform conditions and acceptable range ran from neutral to 1.5 (midpoint between ‘Slightly Warm’ and ‘Warm’) on thermal sensation scale and contained all comfortable and slightly uncomfortable votes on thermal comfort scale. Under non-uniform conditions overall thermal acceptability and comfort were correlated closely. However, overall thermal sensation was apart from the other two responses and non-uniformity of thermal sensation was found to be the reason for the breakage. Combining the effects of overall thermal sensation and non-uniformity of thermal sensation, a new thermal acceptability model was proposed and the model was testified to be applicable to uniform and non-uniform conditions over a wide range of whole body thermal state from neutral to warm.

Effects of Habitual Water Exercise on Heart Rate, Oxygen Uptake, Rectal Temperature and Thermal Sensation Scale

本研究は，水中運動習慣の有無が仰臥位フローティング時の心拍数，酸素摂取量，直腸温および主観的温度感覚スケールに及ぼす影響を明らかにした．被験者は，30名とした．被験者は，水中運動習慣群および対照群の2つのグループに分けられた．陸上仰臥位安静の後に，仰臥位フローティングを20分間行った．その後，陸上座位回復を10間行った．水温は30℃とした．測定項目は，心拍数，直腸温，酸素摂取量，血圧および主観的温度感覚スケールとした．陸上座位回復期の水中運動習慣群の酸素摂取量は，対照群と比較して有意に低値を示した(p＜ 0.05)．仰臥位フローティング時の水中運動習慣群の主観的温度感覚スケールは，対照群と比較して有意に低値を示した(p＜ 0.05)．これらのことから，水中運動習慣は，酸素摂取量および主観的温度感覚スケールに影響を及ぼすことが示唆された．

Perception of the thermal environment in high school and university classrooms: Subjective preferences and thermal comfort

This work shows some of the results of a field study about environmental comfort investigations in classrooms. In this project thermal, acoustic, visual and air quality aspects were analysed in a number of classrooms—13 classrooms at four different high schools of the Provincia di Torino and four typical medium-sized university classrooms of the Politecnico di Torino, Italy. The investigations were carried out during the heating period. Both field measurements and subjective surveys were performed at the same time during the regular lesson periods. This paper focuses on thermal comfort, which may have a significant effect on the students’ performance, in terms of attention, comprehension and learning levels. The measurement campaign consisted in measuring the thermal environment parameters—air temperature, mean radiant temperatures, air relative humidity and air velocity. Through these data, the thermal comfort Fanger's indices (predicted mean vote (PMV), and predicted percentage of dissatisfied (PPD)people) were calculated, the actual people clothing and metabolic rate being known. The subjective survey involved questions on the thermal environmental perception. They basically investigated the thermal environment acceptability and preference. Moreover, a judgement based on the typical seven point thermal sensation scale (Fanger 7-points scale) was also asked. Through the elaboration of the questionnaire data, the actual percentage of dissatisfied (PD) people of the felt thermal environment was evaluated. The judgements about the thermal environment were compared with the results of the field measurements. Moreover, the subjective mean votes were compared with the thermal environment perceptions in terms of acceptability and preference.

Thermal comfort and clothing insulation of resting tent occupants at high altitude

Thirty-nine males and 18 females, in six groups, participated in six high altitude treks (each lasting 3–4 weeks and climbing up to 5500 m) in the Himalaya and Karakoram. Inverse relationships between mean overnight total insulation (sleeping bag plus clothing) and air temperature in tents were recorded for all treks. Average overnight thermal sensations varied little with air temperature as the subjects modified their clothing insulation to maintain thermal sensations warmer than ‘neutral’ for all treks. For combined treks, subjects adjusted their mean overnight total insulation up to 7 clo for thermal sensations of between 0 (‘neutral’) and +1 (‘slightly warm’) on average, measured on the standard seven-point thermal sensation scale developed for everyday low-altitude conditions. Very few subjects (3% of all daily responses, on average) reported ‘cool’ or ‘cold’ sensations. General tent discomfort increased with altitude suggesting that subjects interpreted tent comfort predominantly in terms of thermal outdoor conditions.