Ratings Of Thermal Comfort Research Articles

Equivalent contact temperature (ECT) for personal comfort assessment – definition of comfort limits for winter conditions

This article revisits the Equivalent Contact Temperature (ECT) model by incorporating winter scenarios with seat heating, which were unaddressed in previous studies. The research focuses on enhancing the model’s accuracy in evaluating thermal comfort for seated individuals under non-uniform conditions, particularly for the buttocks and back. These contact areas are crucial for both local and overall comfort, especially with Personalised Environmental Control Systems (PECS), like seat heating and ventilation, which operate close to the body. PECS are more energy efficient than traditional HVAC systems, offering customisation to individual comfort preferences while enhancing individual thermal comfort and energy efficiency in buildings and vehicles. A participant study at air temperatures of 17 °C and 18 °C validated the ECT approach, confirming the effectiveness of seat heating and revealing key correlations between ECT values and thermal comfort ratings. Additionally, an equivalent skin temperature and a comfort evaluation scheme for winter conditions were introduced.

Physiological and cognitive responses to load carriage in the cold

Load carriage is a vital role related task for military, emergency service, and search and rescue personnel, through the transport of critical equipment. From an external validity perspective, a common oversight in previous research is the effect of multiple stressors during load carriage; for example, the inclusion of adverse environmental conditions and/or concurrent cognitive tasks. Therefore, this study aimed to quantify physiological and cognitive changes over time during military specific fast-paced lower-weight load carriage in a cold environment. With approval from the University of Chichester’s Ethics Committee, nine participants completed a load carriage task consisting of 20 min walking at 5.1 km∙h-1, 40 min walking at 6.5 km∙h-1, followed by 8 × 9 s shuttles running at 11 km∙h-1 in an environmental temperature of −10°C. Participants wore overalls whilst carrying 16 kg of external load (10 kg belt-webbing, 6 kg body armour). Throughout, measurements were taken of heart rate, core and skin temperatures, expired gas (VO2), and ratings of physical exertion and thermal comfort. Six military-specific auditory n-back tasks (MSANT) were completed across the trial. The rating scale of mental effort (RSME) quantified mental exertion during the load carriage task. Statistical differences within variables were evaluated using a one-way repeated measures ANOVA with post-hoc analysis employed to identify differences between timepoints. Heart rate and VO2 behaved as expected, with increases after the 5.1 to 6.5 km∙h-1 speed escalation (Pbonf< 0.001); heart rate also increased during the shuttles compared to the first 6.5 km∙h-1 collection (Pbonf = 0.003). A main effect rise for core temperature was evident (Pbonf < 0.001), increasing after 25 min at 6.5 km∙h-1 (Pbonf = 0.009). Skin temperature presented a main effect (Pbonf < 0.001) with an initial decrease and plateau occurring after 15 min. There was no main effect for MSANT or RSME at MSANT completion timepoints (P’s= 0.935 and 0.368 respectively). However, during non-MSANT completion timepoints, RSME was greater from 25 min onwards compared to 5 min (Pbonf < 0.05) signifying an increase in inter-task cognitive demand, oppose to a period of relative mental recovery. This reduced efficiency could be exacerbated during concurrent or extended physical and cognitive tasks. This study is the first to examine physiological and cognitive responses to fast-paced lower-weight load carriage in the cold, progressing understanding of occupational performance in representative environments. These performance data can inform training protocols and operation approaches by highlighting higher inter-task cognitive demand, potentially emphasising an avenue for mitigation strategies.

An evaluation of the effects of localised skin cooling on microvascular, inflammatory, structural, and perceptual responses to sustained mechanical loading of the sacrum: A study protocol.

This study protocol aims to investigate how localised cooling influences the skin's microvascular, inflammatory, structural, and perceptual tolerance to sustained mechanical loading at the sacrum, evaluating factors such as morphology, physiology, and perceptual responses. The protocol will be tested on individuals of different age, sex, skin tone and clinical status, using a repeated-measure design with three participants cohorts: i) young healthy (n = 35); ii) older healthy (n = 35); iii) spinal cord injured (SCI, n = 35). Participants will complete three testing sessions during which their sacrum will be mechanically loaded (60 mmHg; 45 min) and unloaded (20 min) with a custom-built thermal probe, causing pressure-induced ischemia and post-occlusive reactive hyperaemia. Testing sessions will differ by the probe's temperature, which will be set to either 38°C (no cooling), 24°C (mild cooling), or 16°C (strong cooling). We will measure skin blood flow (via Laser Doppler Flowmetry; 40 Hz); pro- and anti-inflammatory biomarkers in skin sebum (Sebutape); structural skin properties (Optical Coherence Tomography); and ratings of thermal sensation, comfort, and acceptance (Likert Scales); throughout the loading and unloading phases. Changes in post-occlusive reactive hyperaemia will be considered as the primary outcome and data will be analysed for the independent and interactive effects of stimuli's temperature and of participant group on within- and between-subject mean differences (and 95% Confidence Intervals) in peak hyperaemia, by means of a 2-way mixed model ANOVA (or Friedman). Regression models will also be developed to assess the relationship between absolute cooling temperatures and peak hyperaemia. Secondary outcomes will be within- and between-subject mean changes in biomarkers' expression, skin structural and perceptual responses. This analysis will help identifying physiological and perceptual thresholds for the protective effects of cooling from mechanically induced damage underlying the development of pressure ulcers in individuals varying in age and clinical status.

The relationship between thermal comfort, performance, and electroencephalogram during cognitive tests at normal indoor temperatures in summer

The relationship between thermal comfort, performance, and electroencephalogram during cognitive tests at normal indoor temperatures in summer

Living in Western Australia induces some physiological adaptations of seasonal acclimatisation in the surgical burns team

ABSTRACT Seasonal acclimatization is known to result in adaptations that can improve heat tolerance. Staff who operate on burn injuries are exposed to thermally stressful conditions and seasonal acclimatization may improve their thermoeffector responses during surgery. Therefore, the aim of this study was to assess the physiological and perceptual responses of staff who operate on burn injuries during summer and winter, to determine whether they become acclimatized to the heated operating theater. Eight staff members had physiological and perceptual responses compared during burn surgeries conducted in thermoneutral (CON: 24.1 ± 1.2°C, 45 ± 7% relative humidity [RH]) and heated (HOT: 31.3 ± 1.6°C, 44 ± 7% RH) operating theaters, in summer and winter. Physiological parameters that were assessed included core temperature, heart rate, total sweat loss, sweat rate, and urinary specific gravity. Perceptual responses included ratings of thermal sensation and comfort. In summer, CON compared to winter CON, baseline (85 ± 15 bpm VS 94 ± 18 bpm), mean (84 ± 16 bpm VS 93 ± 18 bpm), and peak HR (94 ± 17 bpm VS 105 ± 19 bpm) were lower (p < 0.05), whereas core temperature was not different between seasons in either condition (p > 0.05). In HOT, ratings of discomfort were higher in summer (15 ± 3) than winter (13 ± 3; p > 0.05), but ratings of thermal sensation and sweat rate were similar between seasons (p > 0.05). The surgical team in burns in Western Australia can obtain some of the physiological adaptations that result from seasonal acclimatization, but not all. That is most likely due to a lower than required amount of outdoor heat exposure in summer, to induce all physiological and perceptual adaptations.

Comparative feasibility study of physiological signals from wristband-type wearable sensors to assess occupants' thermal comfort

Comparative feasibility study of physiological signals from wristband-type wearable sensors to assess occupants' thermal comfort

Modeling, optimization, and economic analysis of a comprehensive CCHP system with fuel cells, reverse osmosis, batteries, and hydrogen storage subsystems Powered by renewable energy sources

Modeling, optimization, and economic analysis of a comprehensive CCHP system with fuel cells, reverse osmosis, batteries, and hydrogen storage subsystems Powered by renewable energy sources

The characterization of thermal perception in recreational surfers wearing wetsuits

The purpose of this study was to characterize the perception of heat loss, comfort, and wetness in recreational surfers wearing wetsuits, to compare these data with changes in skin temperature reported in prior studies, and to examine the impact of wetsuit thickness, zipper location, and accessory use on thermal sensation and comfort. Following their surf session, nine-hundred and three male (n=735) and female (n=168) recreational surfers responded to a series of questions regarding thermal comfort/sensation, wetsuit characteristics, and surfing history. Average whole body thermal sensation rating was 0.8±3.6 on a scale of -10 to +10 and average whole body thermal comfort rating was 1.5±1.2, midway between "just comfortable" and "comfortable." Overall, surfers felt coldest in their feet, hands, and head. Under their wetsuits, surfers felt the coldest, wettest, and least comfortable in their chest, lower legs, lower arms, and upper back. Wetsuit accessory use had the greatest impact on regions identified as coldest, least comfortable, and wettest. These data suggest that wetsuit design should focus on optimizing water access points and improving accessories for the feet, hands, and head.

Thermal Comfort Improvement Strategies for Outdoor Spaces in Traditional Villages Based on ENVI-Met: Shimengao Village in Chizhou City

The thermal comfort of outdoor spaces in traditional villages must be improved because high building density combined with complex and narrow spaces leads to a poor thermal environment. In traditional villages, outdoor spaces are the most frequently used places by local residents and tourists. In this study, the Shimengao Village in Tangxi Town, Chizhou City, a typical mountainous area in the southern Anhui Province, was selected as the research object, and Depthmap software was used to identify the most frequently used outdoor spaces. The spatial layout and three different outdoor spaces of the traditional village were measured and validated using ENVI-met software. In addition, the distribution of thermal comfort in the core area of the village and influencing factors were analyzed. Our results demonstrated that during summer, PET reached its highest value at 15:00, exhibiting a poor thermal environment in the core area of traditional village integration. From 15:00 to 21:00, PET values declined, resulting in improved thermal comfort levels. Open spaces had better thermal comfort ratings throughout the day. The thermal comfort distribution of three different types of outdoor space in traditional villages was also analyzed. The courtyard space had the worst thermal comfort, followed by the street space, whereas the square space had the best thermal comfort environment. This was correlated with the spatial layout of traditional villages, external facilities of buildings, microlandscapes (plants, water availability, etc.), and outdoor ground materials. Hence, we propose that optimizing the overall spatial layout of a traditional village, increasing the external facilities of buildings, creating “micro landscapes,” and optimizing the materials of outdoor spaces are important for improving the thermal comfort of the outdoor spaces of traditional villages.

A novel method for calculation of the CO2 concentration impact on correlation between thermal comfort and human body exergy consumption

The majority of studies dealing with the correlation between human body exergy consumption and thermal comfort, use adopted, constant values of metabolic rate for appropriate activity level. Taking into account correlations between metabolic rate and the occupant’s exhaled CO2 volumetric flow rate, this study proposes a novel method for the calculation of metabolic rate using measured CO2 concentration in the indoor air. Using measured values of the air and radiant temperature, relative humidity and air velocity, and calculated values of metabolic rate, the human body exergy consumption rate and corresponding Predicted Mean Vote (PMV) are calculated. Moreover, a novel polynomial relation between them is proposed. Results show that metabolic rate values vary in the range of 0.97 to 1.54 met which leads to significantly wider range of PMV and human body exergy consumption rate comparing to the assumed value of 1.2 met for sedentary school activity. According to the obtained relation, the minimal value of the human body exergy consumption rate occurs for PMV = - 0.02. Results of this study imply that treating CO2 concentration as variable does have an impact on the thermal comfort assessment, providing enhanced correlations between thermal comfort and human body exergy consumption rate.

Improving room temperature stability and operation efficiency using a model predictive control method for a district heating station

Improving room temperature stability and operation efficiency using a model predictive control method for a district heating station

Evaluation of cognitive performance in high temperature with heart rate: A pilot study

Real-time monitoring and evaluation of cognitive performance based on physiological indicators is a potentially new measure to ensure high air temperature safety. Heart rate might be an appropriate physiological indicator, yet it still needs several direct shreds of evidence. This study analyzed the relation between heart rate and cognitive performance at high air temperatures, based on the experimental data obtained from three phases of climate-controlled experiments. The climate-controlled experiments include five temperature levels of 26, 30, 33, 37, and 39 °C, and two relative humidity levels of 50% and 70%. During the experiments, eight cognitive tests were conducted to assess the basial cognitive performance, heart rate was continuously monitored, and the ratings of alertness and thermal sensation, comfort, and acceptability were documented. A total of 104 healthy subjects took part in the three phases of experiments, and 1478 valid samples were obtained. By analyzing the experimental data comprehensively, the results show that when the heart rate went up to 90bpm, the speed and accuracy of Stroop and d2 test would decline significantly(p < 0.05). The accuracy of Visual learning, Addition, Multiplication, and Typing only dropped significantly when the heart rate reach a level of 100bpm(p < 0.05). There was an inverted U-shaped relation between the relative accuracy of cognitive tests and heart rate. Based on the quadratic regression equation with a downward opening, the Heart Rate-Cognitive performance (HR-CP) model was built up. The R2 value of all regression equations is close to or greater than 0.8. These results suggest that heart rate might be a potential physiological indicator to evaluate the effects of high air temperature on cognitive performance.

Impact of spectators attendance on thermal ambience and water evaporation rate in an expansive competitive indoor swimming pool

On a big competition swimming pool, the current research is primarily focused on the numerical investigation of the effect of occupational level on temperature, relative humidity, thermal comfort, and water evaporation rate. For this analysis, ANSYS–Fluent Computational fluid dynamics (CFD) was used, with four levels of attendance being considered: 25%, 50%, 75%, and 100% of the capacity of the spectators' area. In addition, a fifth case for the 100% attendance case was examined with a different configuration of the spectators' area jets. According to the findings, as attendance increased, the average values of temperature and Predicted Mean Vote (PMV) inside the space increased, while the average value of relative humidity decreased. In comparison to a 25% attendance capacity, the average values of temperature and PMV inside the space for a 100% attendance capacity were increased almost by 8% and 122%, respectively, while the average value of relative humidity was decreased by approximately 10%. For the fifth case, the revised spectators' area jets configuration for a full attendance capacity decreased the space's average temperature and PMV values by roughly 5% and 14%, respectively. While the average value of relative humidity was increased by about 4%.

The Effect of an Evaporative Cooler on the Thermal Performance of Passive Ventilation System Coupled with EAHE: An Experimental Investigation

An experimental study of a two-storey structure with a passive ventilation system is conducted in August, with the severe summer environment of Kut, Iraq. The experimental model consists of a solar chimney combined with a hybrid cooling system comprised of an Earth-air heat exchanger and an evaporative cooler. Each storey has a size of 1 m3, while the dimensions of the vertical solar chimney were 3m height, 1m width and 0.3m depth. The dimensions of the evaporative cooler were (0.3 * 0.3 * 0.6) m3; it has a two-nozzle water spray system and a low-power fan with a speed of 0.8 m/s. The Earth-air heat exchanger was 17 m long, 10.2 cm in diameter and 3 m deep under each floor. Two instances were investigated with and without EV for two separate daytimes (2-8-2021 and (3-8-2021). The findings revealed that EV increases the relative humidity inside each storey and enhances the thermal comfort rate. Based on recorded data, the relative humidity rate ranged from 35% to 42%, contrasted to the exterior relative humidity, which did not surpass 13%. In addition, the EV assisted in lowering the indoor temperature of each storey by 4 °C. Finally, due to the high solar radiation at the Kut city location in Iraq, the passive ventilation rates for the solar chimney were satisfactory for both storeys.

Performance on heating human body of an optimised radiant-convective combined personal electric heater

In this study, we developed an optimised radiant-convective combined personal electric heater, considering the limitations of traditional personal heaters that heat the human body through heat transfer of single convection or single radiation. Based on human participant experiments in simulated environments, the heating performance of the optimised personal heater on the human body was tested. The initial indoor air temperature in the experimental room was set to 14 °C. Twenty-four healthy young college students, including 12 males and females, were recruited as participants. They were required to experience three types of personal heaters in a sitting position: optimised combined personal heater (PHS R + C ), convective personal heater (PHS C ), and radiant personal heater (PHS R ). During the 80-min-long experiment, their subjective ratings of thermal comfort, perceived air quality, sweating sensation, air movement sensation, and sick building syndrome were collected using questionnaires, and physiological parameters, such as skin temperature, tympanic temperature, and heart rate, were measured. The obtained results showed that, compared with PHS C and PHS R , PHS R + C increased the overall thermal sensation more rapidly (0.083 scale/min), and maintained the human body at a warmer condition. Moreover, when using PHS R + C , mean skin temperature and its change rate, and the thermal sensation vote of all local body parts were higher. The results indicate that the heating performance of this newly developed combined personal heater surpassed that of the two traditional types. Moreover, compared to using PHS C and PHS R , over 27% of the energy consumption was saved using PHS R + C . •An optimised radiant-convective combined personal heater was developed. •Heating performance of the optimised personal heater surpassed two common heaters. •Over 27% of energy consumption can be saved when using the optimised personal heater.

Radiant asymmetric thermal comfort evaluation for floor cooling system – A field study in office building

Radiant cooling systems have the potential of reducing energy when compared with conventional air-conditioning systems. Thermal comfort evaluations for radiant cooling systems mainly focused on floor heating, chilled ceiling, and warm/cool wall, few have been known about the radiant floor cooling system. To validate the applicability of existing dissatisfaction models on radiant floor cooling systems, a field survey with continuous environmental measurements and subjective questionnaires was carried out in an office building in Shanghai. The results show that radiant asymmetries can affect occupants’ thermal comfort and acceptance rate significantly. The radiant floor cooling tends to cause more local discomfort complaints in the feet and calf parts than other radiant heating and cooling systems. The relationship (equation) between thermal dissatisfaction and asymmetrical radiations was developed, and the temperature thresholds s for the radiant floor cooling system were calculated. Based on these results, the short-term (2 h) and long-term (8 h) exposures at different levels of asymmetric radiation were compared and showed significant differences in occupants’ thermal satisfaction. The phenomenon of multi-directional asymmetric radiations (vertically and horizontally) was also observed and its effects were explored. Lastly, the design considerations, thermal comfort assessment, energy consumption, and operation strategy for the radiant floor cooling system were discussed.

Numerical modeling and optimization of annual thermal characteristics of an office room with PCM active–passive coupling system

Herein a numerical study was conducted on a PCM coupling room integrated with a PCM active–passive coupling system to optimize it annual thermal characteristics. In detail, four kinds of inorganic composite PCMs were simultaneously introduced into the wall, ventilation cavity and double-layer radiant floor to construct a PCM active–passive coupling system. The numerical model constructed by EnergyPlus was validated based on the experimental result. The simulation results shown that, compared with the room with common radiant floor, the PCM coupling room exhibited a lower annual energy consumption and a higher indoor thermal comfort rate, which was increased by 16.58%. Based on the thermal comfort evaluated by PMV-PPD method and annual energy consumption, a parameter optimization of the double-layer PCM radiant floor was performed, including the PCM thickness, the thermal conductivity and the location of the heat source. It was found that appropriately increasing the total thickness of the PCM layer could effectively enhance its heat storage capacity to improve the indoor temperature control effect. Specially, the total thickness and the thickness of the upper and lower PCM layers had optimal values. Furthermore, when the thermal conductivity of the upper PCM layer was fixed, increasing that of the lower PCM layer could improve the heat storage /release efficiency of the floor, while its enhancement effect gradually decreased. In addition, moving up or down the heat source would reduce the utilization rate of the PCMs. The radiant floor exhibited the optimal overall thermal performance when the heat source was placed between the two PCM layers. Finally, after parameter optimization, the PCM coupling room performed an indoor thermal comfort rate as high as 81.58%, while saving 20% of the electricity cost by utilizing the price difference between peak and valley electricity.

Perception of Thermal Comfort during Skin Cooling and Heating.

Due to the static and dynamic activity of the skin temperature sensors, the cutaneous thermal afferent information is dependent on the rate and direction of the temperature change, which would suggest different perceptions of temperature and of thermal comfort during skin heating and cooling. This hypothesis was tested in the present study. Subjects (N = 12; 6 females and 6 males) donned a water-perfused suit (WPS) in which the temperature was varied in a saw-tooth manner in the range from 27 to 42 °C. The rate of change of temperature of the water perfusing the suit (TWPS) was 1.2 °C min−1 during both the heating and cooling phases. The trial was repeated thrice, with subjects reporting their perception of the temperature and thermal comfort at each 3 °C change in TWPS. In addition, subjects were instructed to report when they perceived TWPS uncomfortably cool and warm during cooling and heating, respectively. Subjects reproducibly identified the boundaries of their Thermal Comfort Zone (TCZ), defined as the lower (Tlow) and upper (Thigh) temperatures at which subjects reported slight thermal discomfort. During the heating phase, Tlow and Thigh were 30.0 ± 1.5 °C and 35.1 ± 2.9 °C, respectively. During the cooling phase, the boundary temperatures of Tlow and Thigh were 35.4 ± 1.9 °C and 38.7 ± 2.3 °C, respectively. The direction of the change in the cutaneous temperature stimulus affects the boundaries of the TCZ, such that they are higher during cooling and lower during heating. These findings are explained on the basis of the neurophysiology of thermal perception. From an applied perspective, the most important observation of the present study was the strong correlation between the perception of thermal comfort and the behavioral regulation of thermal comfort. Although it is not surprising that the action of regulating thermal comfort is aligned with its perception, this link has not been proven for humans in previous studies. The results therefore provide a sound basis to consider ratings of thermal comfort as reflecting behavioral actions to achieve the sensation of thermal neutrality.

Rice husk and thermal comfort: Design and evaluation of indoor modular green walls

Abstract Green walls are vertical greening structures where varied plant species grow. They are conceived as a form of urban landscape and have numerous environmental, social and economic benefits. In fact, these structures have positive effects on air quality, thermal and acoustic insulation, microclimate, psychophysical well-being and urban design. In the framework of thermal comfort, several studies demonstrated the potential of green walls to improve indoor thermal comfort and reduce heat flows through the wall of buildings. This research evaluates the thermal efficiency of two modular green walls that present an alternative substrate as growing medium. This substrate is composed of loam soil and rice husk, an agricultural organic waste derived from the rice milling process. The choice of rice husk is inspired by principles of circular economy in order to reduce the environmental impact and costs of the substrate used in greening applications. The alternative substrate was compared with expanded clay aggregate, used for plant cultivation in living walls, and the analysis was divided into two phases. Firstly, field experiments were carried out on three plant species (Chlorophytum, Dieffenbachia and Spathiphyllum) to evaluate the efficacy of these substrates to grow plants. The efficacy of the substrate was evaluated through the measurement of the concentration of chlorophyll, the determination of the growth index of plants and a qualitative observation of the root development. Secondly, two modular green walls with varied substrates and plants were designed and tested from the point of view of the thermal comfort, using the open source software TerMus-G. After the transmittance value was obtained as output for each green wall module, the heat flow and the relative variation were calculated and compared to the indoor supporting walls. This article presents a valid methodology approach to evaluate the efficiency of green walls substrate and its thermal performance. This methodology differs from those found in scientific literature and represents a valid alternative. The present research demonstrates the ability of designed modules and, more generally, of indoor green walls to increase thermal insulation without causing condensation. Furthermore, the investigation shows a positive contribution both in winter and in summer. Finally, the use of this undervalue by-product rice husk mixed with loam soil shows to be appropriate for green wall application, providing better performance than the expanded clay in terms of thermal comfort and plant growth rate. Moreover, its use as substrates should further improve the ecological footprint of green vertical structures and reduce costs.

Evaluation of individual thermal sensation at raised indoor temperatures based on skin temperature

In this study, we further investigate whether skin temperature can also assess individual thermal sensation as an effective physiological index while previous studies did not draw broadly generalizable conclusions at high temperature. The climate-controlled experiments include five temperature levels of 26, 30, 33, 37 and 39 °C, two relative humidity levels of 50% and 70%, and two activity levels with light and moderate and in which the estimated average metabolic rate were respectively 58 W/m2 and 165 W/m2. A total of 136 healthy subjects who lived in hot-humid climate for a long time participated in these experiments. During the experiments, the ratings of thermal sensation, comfort and acceptability were documented, local skin temperatures were continuously monitored, and five mean skin temperatures were calculated. Using Fisher discriminant analysis to model thermal sensation from skin temperature, then obtaining the thresholds of local and mean skin temperatures corresponding to different thermal sensation categories, and finally verifying the accuracy of the models assessment. The results show that the skin temperature can also predict thermal sensation at high temperatures of 30–39 °C beyond the range of normal temperatures. The proposed evaluation models show a high accuracy to predict the “hot/very hot” category, and up to 93% accuracy of predicting thermal sensation from wrist skin temperature. Additionally, thermal adaptation to high temperature and humidity can affect the prediction accuracy of “hot/very hot” category from skin temperature. The results of this study provide an important basis for early warning when human's safety risk occurs under high temperatures.