Thermal Comfort Sensation Research Articles

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.

Effect of Clothing Thermal Properties on the Thermal Comfort Sensation During Active Sports

This paper reports on an experimental investigation on the effect of clothing thermal properties on the comfort sensations of wearers during sport activities. A sweating manikin"Walter" - was used to measure the clothing thermal properties (namely, thermal insulation, moisture vapor resistance and moisture accumulation within clothing) of five tracksuits. The average comfort sensations of five men wearing each of the five tracksuits were correlated with the thermal properties of the tracksuits measured from the sweating manikin - "Walter". It was found that the thermal comfort sensations during active sports were strongly related to the moisture vapor resistance and moisture accumulation within clothing. The overall comfort of sportswear during sports activities was very much related to the moisture related comfort sensations and clothing properties.

Predictive controllers for thermal comfort optimization and energy savings

The present work is focused on the study of indoor thermal comfort control problem in buildings equipped with HVAC (heating, ventilation and air conditioning) systems. The occupants’ thermal comfort sensation is addressed here by the well-known comfort index known as PMV (predicted mean vote) and by a comfort zone defined in a psychrometric chart. In this context, different strategies for the control algorithms are proposed by using an only-one-actuator system that can be associated to a cooling and/or heating system. The first set of strategies is related to the thermal comfort optimization and the second one includes energy consumption minimization, while maintaining the indoor thermal comfort criterion at an adequate level. The methods are based on the model predictive control scheme and simulation results are presented for two case studies. The results validate the proposed methodology in terms of both thermal comfort and energy savings.

정기적인 찜질 훈련이 청년과 노년여성의 내열성 증진에 미치는 영향

We analyzed the effects of regular Jjimjilbang(Korean sauna) exposure on the heat tolerance in young and old females. Subjects were young(n=7) and old(n=7) females who never had a bath in Jjimjilbang for last year. Jjimjilbang training group took a bath in Jjimjilbang once a week 19 times. Jjimjibang expsure was limited three times per day, Jjimjil were taken free way. To prove the effects of the heat tolerance, Subjects were exposed to hot and humid air<TEX>$(40.0{\pm}0.5^{\circ}C,\;60{\pm}5%RH)$</TEX>. In the condition, subjects were taken a foot bathing<TEX>$(40.0{\pm}0.5^{\circ}C)$</TEX> and simulated for 30 min., and rectal temperature, skin temperatures, clothing microclimate, blood pressure, total body weight loss, local sweat and subjective sensation were measured. The results are as follow: Rectal temperature, skin temperatures, clothing microclimate, total body weight and subjective thermal comfort sensation were decreased gradually(p<.001). Local sweat of upper arm was decreased(p<.01). In conclusion. the regular Jjimjilbang exposure has positive effects upon improvement in regulation of body temperature, especially in heat tolerance.

Experimental study on physiological responses and thermal comfort under various ambient temperatures

This study mainly explored the thermal comfort from the perspective of physiology. Three physiological parameters, including skin temperature (local and mean), electrocardiograph (ECG) and electroencephalogram (EEG), were investigated to see how they responded to the ambient temperature and how they were related to the thermal comfort sensation. A total of four ambient temperatures (21 °C, 24 °C, 26 °C and 29 °C) were created, while the other thermal conditions including the air velocity (about 0.05 ± 0.01 m/s) and the air humidity (about 60 ± 5 m/s) were kept as stable as possible throughout the experiments. Twenty healthy students were tested with questionnaire investigation under those thermal environments. The statistical analysis shows that the skin temperature (local and mean), the ratio of LF norm to HF norm of ECG and the global relative power of the different EEG frequency bands will be sensitive to the ambient temperatures and the thermal sensations of the subjects. It is suggested that the three physiological parameters should be considered all together in the future study of thermal comfort.

Experimental study of an auto-controlled automobile air conditioning system with an externally-controlled variable displacement compressor

In this paper, an experimental study of an auto-controlled mobile air conditioning (MAC) system with an externally-controlled variable displacement compressor (EVDC) is performed and analyzed. A new displacement control method of EVDC is developed concerning about evaporator characteristics and in-car temperature fluctuation, which indicate the quality of the MAC system. Based on occupant’s thermal comfort, the wind-tunnel test results show that the MAC system with an EVDC can maintain the deviation of in-car temperature no more than 2 °C compared with the occupants’ desired one. This MAC system gives the occupants a good thermal comfort sensation in the rapid changing environment. The comparison shows that the discharge pressure changes of EVDC vary faster than that of the fixed displacement compressor, which reflects the effect of the internal climate changes.

Passenger Thermal Comfort in Vehicles - A Review

A comprehensive survey is presented of research studies regarding thermal comfort issues in the vehicle passenger compartment environment. The work is classified according to whether it is concerned with the passenger compartment environment or the condition of the passengers and their interaction with the compartment. The review includes factors associated with passenger compartment conditions, such as flow field and temperature field, which affect the thermal comfort of the occupants. The evolution of thermal comfort models is reviewed. Also included are various computational and empirical models for predicting physiological response and the sensation of thermal comfort in the non-uniform transient environment of a vehicle. The use of thermal manikins in these studies is also incorporated. Areas in which additional information is required are identified and comments are made regarding future research directions.

NON-LINEAR PREDICTIVE CONTROLLERS FOR THERMAL COMFORT OPTIMIZATION AND ENERGY SAVING

The present work is focused on the study of indoor thermal comfort control problem in buildings equipped with heating systems. The occupants' thermal comfort sensation is addressed here by a comfort index known as PMV (Predict Mean Vote). In this context, two control algorithms are proposed by using only-one-actuator system associated to the heating system. The methods are based on the model predictive control scheme and on the improvement of the PMV index together with energy minimization. Simulation results - obtained by using the weather data file for the city of Curitiba, Brazil - for two case studies: i) variations between low and moderate occupants metabolic rates and ii) variations between moderate and high occupants metabolic rates are presented to validate the proposed methodology in terms of room air temperature, relative humidity and PMV control.

On the use of bioclimatic architecture principles in order to improve thermal comfort conditions in outdoor spaces

The present paper describes a process for designing and applying several techniques based on bioclimatic architecture criteria and on passive cooling and energy conservation principles in order to improve the thermal comfort conditions in an outdoor space location located in the Great Athens area. For that reason, the thermal comfort conditions in 12 different outdoor space points in the experimented location have been calculated using two different thermal comfort bioclimatic indices developed to be used for outdoor spaces. The used indices were the following: (a) “Comfa”, which is based on estimating the energy budget of a person in an outdoor environment and (b) “thermal sensation”, based on the satisfaction or dissatisfaction sensation under the prevailing climatic conditions of the outdoor spaces. Calculations were performed during the summer period and two different scenarios of the constructed space parameters have been considered. The first scenario consists of a conventionally constructed space, while the second one includes various architectural improvements according to the bioclimatic design principles. The two bioclimatic indicators were used for calculating the outdoor thermal comfort conditions in the above-mentioned outdoor space locations for both scenarios and the effect of the bioclimatic design architectural improvements on the human thermal comfort sensation was presented and analysed.

Effects of ambient temperature steps on thermal comfort requirements

The purpose of this study was to determine the thermal comfort requirements for steps in temperature. Thirty male subjects were exposed for 50 min to a 34 or 37 degrees C condition, and then quickly transferred to a cooler environment of 31, 28, 25, and 22 degrees C for 50 min. Mean skin temperature was continuously measured, and the subjects reported their thermal sensation and comfort sensation every 2 min. Just after the step changes, the mean skin temperature immediately decreased, while the thermal sensation overshot and gradually rose again. Both the skin temperature and the thermal sensation seemed to reach a constant level within about 20 min. However, there were differences in the mean skin temperature and the neutral temperature derived from the correlation between the ambient temperature and the thermal sensation even 50 min after the steps, due to the thermal environmental condition before the changes of temperature. The change in the neutral temperature with time was expressed as two attenuating equations. These equations indicate that there is an obvious difference between the neutral temperatures due to the thermal condition before step changes, and that it takes >50 min after the step changes to reach the steady state. It is expected that these equations predict in quantitative terms the thermal comfort requirements within a given experimental condition.

THERMAL COMFORT BASED PREDICTIVE CONTROLLERS FOR BUILDING HEATING SYSTEMS

This work is focused on indoor thermal comfort control problem in buildings equipped with HVAC (Heating Ventilation and Air Conditioning) systems. The occupants thermal comfort is addressed here by a comfort zone in the psychometric chart and the PMV (Predict Mean Vote) index. In this context, three control algorithms are proposed by using only-one-actuator system associated to a heating equipment. The methods are based on the model predictive control scheme and on the improvement of indices related to occupants thermal comfort sensation. Simulation results – obtained by using the weather data file for the city of Curitiba, Brazil – are presented to validate the proposed methodology in terms of room air temperature, relative humidity and PMV control.

New comfort index during combined conditions of moderate low ambient temperature and traffic noise

This study's aim is to propose a new comfort index for indicating the combined effect of cold and noise stress on the human state of mind. Twenty-two male students were exposed to 20 combined conditions involving four operative temperature levels and five noise levels. The subjects reported their sensations regarding each combined condition. The results show that the auditory condition significantly affected the hot sensation as well as the noise sensation, and that the thermal condition also significantly affected the noise sensation. Both temperature and noise affected obviously the universal comfort and discomfort sensations. Consequently, two kinds of equi-comfort charts were derived. One of the charts, which represents the equal universal comfort sensation derived from the combination of thermal and auditory comfort sensation, demonstrates the exclusivity of the combined effects. The other chart indicates temperature and noise levels in order to quantitatively evaluate the combined effect of cold and noisy conditions based on the experimental results. This chart can reasonably predict human comfort sensations within this experimental condition.

Effects of wearing aircrew protective clothing on physiological and cognitive responses under various ambient conditions

Heat stress can be a significant problem for pilots wearing protective clothing during flights, because they provide extra insulation which prevents evaporative heat loss. Heat stress can influence human cognitive activity, which might be critical in the flying situation, requiring efficient and error-free performance. This study investigated the effect of wearing protective clothing under various ambient conditions on physiological and cognitive performance. On several occasions, eight subjects were exposed for 3 h to three different environmental conditions; 0°C at 80% RH, 23°C at 63% RH and 40°C at 19% RH. The subjects were equipped with thermistors, dressed as they normally do for flights (including helmet, two layers of underwear and an uninsulated survival suit). During three separate exposures the subjects carried out two cognitive performance tests (Vigilance test and DG test). Performance was scored as correct, incorrect, missed reaction and reaction time. Skin temperature, deep body temperature, heart rate, oxygen consumption, temperature and humidity inside the clothing, sweat loss, subjective sensation of temperature and thermal comfort were measured. Rises in rectal temperature, skin temperature, heart rate and body water loss indicated a high level of heat stress in the 40°C ambient temperature condition in comparison with 0°C and 23°C. Performance of the DG test was unaffected by ambient temperature. However, the number of incorrect reactions in the Vigilance test was significantly higher at 40°C than at 23°C (p = 0.006) or 0°C (p = 0.03). The effect on Vigilance performance correlated with changes in deep-body temperature, and this is in accordance with earlier studies that have demonstrated that cognitive performance is virtually unaffected unless environmental conditions are sufficient to change deep body temperature.

Displacement ventilation environments with chilled ceilings: thermal comfort design within the context of the BS EN ISO7730 versus adaptive debate

The current design standard BS EN ISO7730 [Moderate thermal environments—determination of the PMV and PPD indices and specification of the conditions for thermal comfort, International Standards Organisation (1995)] is based upon the work of Fanger, and essentially comprises a steady-state human heat balance model that leads to a prediction of the sensation of human thermal comfort for a given set of thermal conditions. The model was derived from laboratory-based measurements conducted in the mid-1960s in relatively ‘conventional’ environments. However, a chilled ceiling operated in combination with displacement ventilation represents a more sophisticated environment as compared with the original conditions in which the Fanger model was derived. This raised a question about the applicability of the current standard when designing for thermal comfort in offices equipped with chilled ceiling/displacement ventilation systems. This paper presents findings from an EPSRC-funded study that sought to answer the above question. Human test subjects (184 in total) carried out sedentary office-type work in a well-controlled environmental test room that simulated an office fitted with the above system. Measurements of environmental variables were taken at a number of locations near the subjects, each of whom wore a typical office clothing ensemble. The reported thermal comfort sensations were compared with values predicted from BS EN ISO7730 over a range of system operating conditions. It was shown that the current standard BS EN ISO7730 may be used, without modification, when designing for the thermal comfort of sedentary workers in offices equipped with chilled ceiling/displacement ventilation systems. These findings are interpreted within the context of a proposed modification to thermal comfort design standards that includes adaptive effects, and the influence of BS EN ISO7730 on the development of other radiant surface/displacement ventilation configurations is discussed.

Biometeorology and recreation in east Mediterranean forests

For better planning and management of landscape units such as forests for recreational purposes there is need for not only to give much emphasis to the visual aesthetic aspects, but also to understand the microclimate differences among vegetative units and their influence on recreation-seeking humans. Microclimatic measurements were conducted in man-made and natural forests, some neglected and some regularly used for recreation by the population of Israel. Human response to the thermal environment and the mechanism of heat exchange between the body and the environment have been expressed in terms of the sweating rate ( S) and the thermal sensation (TS), which is the perceived thermal comfort sensation at a given S. The results presented show that the S needed to maintain homeothermy and the sensation of thermal comfort are closely related to overhead canopy closure. Specifically, gaps in the tall tree forest and oak scrub formations on south-facing slopes will provide the most comfortable sites in winter and early spring, whereas summer thermal comfort is directly related to tall tree forest canopy closure, preferably on north-facing slopes.

The effects of facial fanning on thermal comfort sensation during hyperthermia.

We studied how facial fanning during hyperthermia improves the thermal comfort sensation. Experiments were carried out on ten male subjects. They were immersed in hot water at 40 degrees C for 45 min. At 20 min and 35 min, fanning (1 m x s(-1)) was applied to their faces for 5 min. Core temperature (Tc) measured as esophageal temperature (Tes) and tympanic temperature (Tty) continued to rise during the immersion, but temporarily decreased during fanning with a delay of 2 or 3 min. Skin temperatures (Ts) on the forehead and cheek continued to increase slightly during immersion, but decreased immediately after the start of fanning. During immersion before face fanning, the time trend of thermal sensation towards the warm level was similar to that of skin temperature on the face, whereas the time trend of thermal comfort ratings towards the uncomfortable level was similar to that of Tc. The scores of both thermal sensation and thermal comfort were reduced significantly immediately after the start of fanning, and their time courses were different to those of Ts and Tty. These results support previous reports that thermal sensation depends on skin temperature, and that thermal comfort depends on both the skin and core temperatures. Moreover, they indicate that both thermal sensation and comfort ratings are affected by the dynamic responses of the cutaneous thermoreceptors when fanning is applied to the face during hyperthermia.

A study on body temperature regulation and residential thermal environments of the elderly—II. residential thermal environments at the kansai district

1. 1. An investigation was carried out on 3 male and 4 female elderly people, from 65 to 78 years ol.d The first survey was made in August and September of 1990 (in summer) and the second in January and February of 1991 (in winter). 2. 2. Matters for investigation were human subjects and thermal environmental elements of houses which were recorded by a portable thermo-recorder and a vinyl resin globe thermometer. Dry bulb temperatures at a height of 0.1 and 1.2 m and wet bulb and globe temperatures at 1.2 m high were recorded in the living room, bedroom, toilet etc., the thermo-recorders which measured air and wet bulb temperatures were kept out of the sun. 3. 3. Data was recorded constantly for 7 days at 20 min intervals. Plans of houses and furniture arrangement which influence the thermal conditions were drawn from video recordings. Physical and psychological surveys of individuals were carried out over 2 days of daily life. 4. 4. Subjects carried the thermo-recorders (YM1, YM2) on their side. Rectal, back of hand, sole of foot and ambient temperatures were measured every 2 min and with thermistor sensors. At the same time, behaviour and clothes, assessment of thermal sensation, comfort sensation and sensation of estimated room temperature were reported. 5. 5. Thermal radiation was measured with thermographs during the winter. Human activity was recorded every minute for 33 h. This report is the result of surveys in summer and winter. 6. 6. The following results were obtained: (i) the air conditioning is used sometimes in the houses of the elderly; (ii) thermal sensation range reported is narrow; (iii) skin surface temperatures of the elderly are relatively high and their range of change is narrow, and the range of rectal temperature in a day is narrow; (iv) high activity and excessive heating cause a rise of rectal temperature and the rectal temperatures are lower at rest time.

Evaluation of thermal environment by real time monitoring SET ∗

1. 1. A system, combining a portable data logger and a personal computer with a GP-IB interface, was developed both to measure environmental variables and also to predict human physiological responses to one's thermal environment. 2. 2. An environmental index: Standard Effective Temperature SET ∗, can also be computed with the personal computer and displayed on the CRT for the real time monitoring of the thermal environment and comfort sensation.

夏期における気温と気流が運動時の人体に及ぼす影響に関する研究

The purpose of this study is to evaluate the effects of air velocity on the human thermal responses during physical exercise. The experiments were carried out in a climatic chamber at different air temperatures ranging from 20℃ to 35℃ and for air velocities of 0.2 m/s, 1.4 m/s and 2.8 m/s. The relative humidity was 50% and the mean radiant temperature was equal to the ambient air temperature. The subjects were six collegiate females and they wore a short-sleeved cotton T shirts and cotton shorts. They stayed for 60 minutes and they took physical exercise for 40 minutes. The exercise intensities were 25 W and 50 W. The physiological responses, i.e., skin temperatures at 12 points, rectal temperature, heart rate, metabolic rate and weight loss were measured. Thermal sensation and comfort sensation were asked. Mean skin temperature, heat balance and skin wettedness were calculated. The effects of air velocities on the thermal responses were expressed in the change of air temperature.

Thermal comfort in the humid tropics: Field experiments in air conditioned and naturally ventilated buildings in Singapore

Thermal comfort field experiments were conducted in Singapore in both naturally ventilated highrise residential buildings and air conditioned office buildings. Each of the 818 questionnaire responses was made simultaneously with a detailed set of indoor climatic measurements, and estimates of clothing insulation and metabolic rate. Results for the air conditioned sample indicated that office buildings were overcooled, causing up to one-third of their occupants to experience cool thermal comfort sensations. These observations in air conditioned buildings were broadly consistent with the ISO, ASHRAE and Singapore indoor climatic standards. Indoor climates of the naturally ventilated apartments during the day and early evening were on average three degrees warmer than the ISO comfort standard prescriptions, but caused much less thermal discomfort than expected. Discrepancies between thermal comfort responses in apartment blocks and office buildings are discussed in terms of contemporary perceptual theory.