Thermal Perception Research Articles

A 0.1% L-Menthol Mouth Swill in Elite Male Rugby Players Has Different Effects in Forwards and Backs.

Menthol mouth swills can improve endurance performance in the heat, which is attributed to attenuations in nonthermally derived thermal sensation (TS) and perception of effort. However, research in elite team-sport athletes is absent. Therefore, this study investigated the performance and TS responses to a 0.1% menthol mouth rinse (MR) or placebo (PLA) among elite male rugby union players. Twenty-seven (15 Forwards and 12 Backs) elite male Super Rugby players completed two 3-minute 15-a-side rugby-specific conditioning blocks, with MR or PLA provided at the start of training (baseline), at the start of each 3-minute block (swill 1 [S1] and swill 2 [S2]), and at the end of training (swill 3 [S3]). TS was assessed using the American Society of Heating, Refrigerating and Air-Conditioning Engineers 9-point Analog Sensation Scale after each swill and at baseline (preconditioning block). Acceptability was measured after baseline swill and S3 using a 5-question Likert scale. Physical performance was measured throughout training using global positioning system metrics. MR attenuated TS from baseline to S1 (P = .003, SD = 1.01) and S2 (P = .002, SD = 1.09) in Forwards only, compared with PLA. Acceptability was higher only for Forwards in MR versus PLA at baseline (P = .003, SD = 1.3) and S3 (P = .004, SD = 0.75). MR had no effect on physical performance metrics (P > .05). MR attenuated the rise in TS with higher acceptability at S1 and S3 (in Forwards only) with no effect on selected physical performance metrics. Longer-duration exercise (eg,a match) in hot-humid conditions eliciting markedly increased body temperatures could theoretically allow favorable changes in TS to enhance performance-these postulations warrant experimental investigation.

Performance evaluation and users’ perception of courtyards role in indoor areas of mediterranean social housing

Cities confront two critical challenges: general overheating and inefficient use of energy resources within their housing buildings, both adversely affecting urban citizens' daily lives. To mitigate these issues, passive techniques offer promising solutions on enhancing building comfort levels from a sustainable approach. Although this energy efficiency of air-conditioning systems in buildings in warm climates has been extensively analysed, the influence of the microclimate of transitional spaces attached to them on this performance has not yet been properly assessed. Investigating the potential benefits of the implementation of courtyards within Seville's social housing infrastructure for passive conditioning purposes is one way of reducing this research gap. Furthermore, the study also includes the subjective perception of users' thermal well-being around these spaces and their own social relationship related to their use. The work relies on detailed data analyses carried out using DesignBuilder software to quantify the benefit effectively accrued from courtyard utilization. Concurrently, user surveys conducted help determine perceived thermal comfort aiding better configuration management and passive design strategies of urban social housing. Findings from monitoring and simulation reveal that courtyards work faultlessly as a highly effective and efficient passive cooling system whilst promoting energy efficiency up to 20,5%. Surveys confirmed these findings with data revealing significant improvements in thermal comforts perception inside courtyards and within indoor spaces adjacent to the courtyards. This research provides novel insights into how architects and urban managers might integrate passive strategies into future designs for optimizing comfort levels in social housing using courtyards as one possible environmental measure for achieving sustainability targets.

An experimental study of thermal comfort zone extension in the semi-open spray space

Pedestrians will experience different heat stress stages from sunlight to semi-open spray space as they shuttle through stations with spray systems. There are few studies on the influence of thermal experience and thermal history of this specific environment on pedestrian thermal comfort. This study explored the dynamic physiological thermal response and thermal perception of humans in the sunlight to semi-open spray space in Qingdao, China. Meteorological and physiological parameters were measured and questionnaires were conducted. The results showed that from outdoor sunlight to semi-open spray space, thermal sensation and thermal comfort were improved, the mean skin temperature of the whole body decreased by 0.5 °C, the neutral standard effective temperature (NSET*) enhanced by 8.8 °C, and the NSET* range (NSET*R) increased by 7.3–10.2 °C. However, after 10 min in the semi-open spray space, the thermal comfort gradually deteriorated. In addition, the main meteorological factors affecting the thermal sensation in sunlight and semi-open spray space were air temperature and mean radiant temperature, and the main physiological factor was the skin temperature of the right upper arm. This study is helpful for the operation design of spray systems and the evaluation of the thermal environment in semi-open spray in cities.

Universal thermal climate index in the Arctic in an era of climate change: Alaska and Chukotka as a case study

The modern unambiguous climate change reveals in a rapid increase of air temperature, which is more distinctly expressed in the Arctic than in any other part of the world, affecting people health and well-being. The main objective of the current research is to explore the inter- and intra-annual changes in thermal stress for people in the Arctic, specifically for two parts of Beringia: Alaska, USA, and Chukotka, Russia, using climatology of the universal thermal climate index (UTCI). Data for 39 locations are taken from the ERA5-HEAT reanalysis for the period 1979–2020. Climatologically, the study area is divided into four subregions in Alaska: North, Interior, West and South, and two in Chukotka: Interior and Coast. The extreme coldest UTCI categories (1 and 2) are most common in coastal locations of northern Alaska and Chukotka, where strong winds exacerbate the low temperatures during winter. The results show that the frequency of category 1 (UTCI<−40°C) varies spatially from a quarter of all hours annually in Alaska North to almost zero in Alaska South. On the other hand, the warmest categories are rarely reached almost everywhere in Alaska and Chukotka, and even categories 7 and 8 (UTCI between +26 and +38°C) are found occasionally only at interior locations. Category 6 with no thermal stress (UTCI between +9 and+26°C) has frequencies up to 3% and 25% in Alaska North and Interior, respectively. The extremely cold thermal stress frequencies have substantially decreased over the 1979–2020 period, especially in Alaska North and Chukotka Coast. At the same time, the number of hours with UTCI in the comfortable category of thermal perception has increased depending on subregion, from 25 to 203 h/year. Overall, a decrease in the UTCI categories of extremely cold stress is coupled with an increase in the comfortable range in both Alaska and Chukotka. The salient conclusion is that, from the point of view of comfort and safety, global warming has a positive impact on the climatology of thermal stress in the Arctic, providing advantages for the development of tourism and recreation.

Paradoxical heat sensation as a manifestation of thermal hypesthesia: a study of 1090 patients with lesions of the somatosensory system.

Paradoxical heat sensation (PHS) is the perception of warmth when the skin is cooled. Paradoxical heat sensation rarely occurs in healthy individuals but more frequently in patients suffering from lesions or disease of the peripheral or central nervous system. To further understand mechanisms and epidemiology of PHS, we evaluated the occurrence of PHS in relation to disease aetiology, pain levels, quantitative sensory testing parameters, and Neuropathic Pain Symptom Inventory (NPSI) items in patients with nervous system lesions. Data of 1090 patients, including NPSI scores from 404 patients, were included in the analysis. We tested 11 quantitative sensory testing parameters for thermal and mechanical detection and pain thresholds, and 10 NPSI items in a multivariate generalised linear model with PHS, aetiology, and pain (yes or no) as fixed effects. In total, 30% of the neuropathic patients reported PHS in contrast to 2% of healthy individuals. The frequency of PHS was not linked to the presence or intensity of pain. Paradoxical heat sensation was more frequent in patients living with polyneuropathy compared with central or unilateral peripheral nerve lesions. Patients who reported PHS demonstrated significantly lower sensitivity to thermal perception, with lower sensitivity to normally painful heat and cold stimuli. Neuropathic Pain Symptom Inventory scores were lower for burning and electric shock-like pain quality for patients with PHS. Our findings suggest that PHS is associated with loss of small thermosensory fibre function normally involved in cold and warm perception. Clinically, presence of PHS could help screening for loss of small fibre function as it is straightforward to measure or self-reported by patients.

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.

The impact of cold, hypoxia, and physical exertion on pistol accuracy and tactical performance

The purpose of this study was to examine the impact of independent cold and combined cold and hypoxic exposures on operational-specific task performance including pistol marksmanship, pistol magazine reload ability, and subjective and objective thermal indices before and after a whole-body physical exertional task. Twelve participants were exposed to Thermoneutral Normoxic (24 °C; FiO2 21%), Cold Normoxic (10 °C; FiO2 21%), and Cold Hypoxic (10 °C; FiO2 14%) conditions for 30min before performing pistol marksmanship at distances of 6.40 and 13.72m and a pistol magazine reload task before and after 3 sets of sandbag deadlifts at 50% body mass. Thermal perception and hand temperatures were collected before and after the physical exertion task. There were no significant differences in Pistol Accuracy performance at distances of 6.40 and 13.72m due to physical exertion, cold, or hypoxia. Following physical exertion, Pistol Accuracy was similar between Thermoneutral and Cold Normoxic conditions but lead to 17% and a 10% reduction in performance during the Cold Hypoxic condition, compared to Thermoneutral and Cold Normoxic conditions. There was no change in Pistol Accuracy for the Thermoneutral Normoxic condition. The pistol magazine reload task was not impacted by physical exertion, but there was a reduction in performance in Cold Normoxic 21% (4.04s) and Cold Hypoxic 16% (3.08s) conditions. Physical exertion did not impact hand temperature but did increase thermal perception scores for all conditions. These findings indicate that cold exposure reduced both tactical dexterity and pistol marksmanship, however, physical exertion may offset these deficits via an increase in thermal perception. Additionally, hypoxemia was the primary mediator of marksmanship performance in cold hypoxic environments following an acute bout of physical exertion. Thus, in cold mountainous environments, marksmen should be aware of their elevation and utilize brief episodes of physical activity to enhance their thermal state when marksmanship is a priority for operational success.

Climatic Variability in Altitude: Architecture, Thermal Comfort, and Safety along the Facade of a Residential Tower in the Mediterranean Climate

This research is part of a wider study on the sustainability of high-rise buildings within the urban environment. The focus here is on wind and temperature stratifications per different height through in situ monitoring on a high-rise residential tower in the Mediterranean climate of Tel Aviv, and their impact on thermal comfort and user safety. The appropriateness of design is discussed in relation to the direct exposure to higher-up wind velocities, the thermal perception of the residents through questionnaires, and the safety and usability of the outdoors space according to height. The potential for advancing the energy efficiency of the structure is also discussed. The study covers a hot and a cold season, focusing on the specificities of the wind regime in the specific climate, through seasonal variations. Results from the monitoring of data confirmed increased wind and gust velocities per building height all year round, reaching the level of danger for the occupants during winter, cancelling, thus a successful operation of the outdoor balcony space. The occupants’ perception and use of the outdoor balcony space per building height were in direct relationship to the increased wind velocities per height. Discussion and conclusions critically evaluate the residential high-rise building typology in the Mediterranean climate through the design of the outdoor balcony space along the height of the envelope. The results set an initial understanding and delineation for future studies, while underlining the complications of designing and occupying tall buildings and the level of detailing required.

Heat vulnerability and street-level outdoor thermal comfort in the city of Houston: Application of google street view image derived SVFs

Heatwaves and urban heat islands disproportionately affect residents of urban areas. Past studies on the heat vulnerability indexes (HVI) to evaluate the heat-related risk have two major limitations: the inability to capture street-level human heat stress and reliance on single meteorological proxies to measure heat exposure. To address these gaps, this study examines the impact of street-level outdoor thermal comfort (OTC) on heat vulnerability in the city of Houston, Texas. OTC refers to an individual's thermal perception of their surroundings. The study estimates the impacts of HVI scores and energy budget (EB) values of OTC on heat-related disease while investigating their spatial distributions and clusters. The results show that the explanatory power of the suggested models on the number of emergency department (ED) visits improved when the street-level OTC had higher HVI scores and more comfortable conditions. A positive bivariate relationship was found between the HVI scores and EB values, showing the highest explanatory power (adj-r2) of around 36%. Chronic disease and heat exposure significantly affected the HVI, whereas tree and sky view factors were crucial determinants of the EB values. These findings provide a new approach to heat vulnerability evaluation at the human scale to effectively address heat-related risk.

Assessment of some Bioclimatic Indices using RayMan Model for Baghdad-Iraq

Abstract The evaluation of bioclimatic conditions on a local scale is still an important topic. It might be a key component of the national plan for the sustainable development of various areas under changing climatic conditions. The present study aimed to examine the behaviour of four bioclimatic indices namely physiologically equivalent temperature (PET), Standard Effective Temperature (SET*), Universal thermal climate index(UTCI) and, Predictive mean vote(Pmv) derived from energy budget models for Baghdad city. The monthly means data of air temperature, relative humidity, wind speed, and solar radiation during the period (1981-2021) were used in this study. All calculations of this study were extracted using RayMan Model. The relationship between PET, Pmv, SET, and UTCI indices in addition to meteorological parameters was also conducted in this study. The results indicate that July and August had the highest values of Pmv (4), SET* (39.4), PET (43.9), and UTCI (39.4). For the majority of the studied indices, the comfortable thermal perception occurred only in March, April, and October. PET and UTCI revealed acceptable comparability in terms of temperature perception when compared to other indices for most months of the year. The maximum heat stress was reported for all indices between May and September, with the lowest stress occurring between January and December. April was the most comfortable month of the year, according to the data. Correlations between UTCI and meteorological parameters found a substantial association with air temperature (0.99) and relative humidity (0.98), respectively. The lowest correlation coefficient (R2=0.69) was found with wind speed. All other indicators indicate a substantial association with the UTCI.

Redefining human thermal perception for the Mediterranean climates

SARS-COV-2 focuses on the comfort of outdoor spaces in large cities. Creating comfortable spaces for children and improving the habitability of cities are essential today. Climate change is real, and its main adverse effects are already being felt: Urban Heat Island and recurring heat waves. Numerous comfort models predict the state of the occupants of space. However, these comfort indices need to be validated in Mediterranean climates. This study tests the COMFA comfort model in a real case in Seville. Thermal monitoring campaigns are carried out during the intermediate seasons of warm weather in a primary school.The main objective is to know the effect of the urban heat island and the climatic conditions to which the person is subjected. For this purpose, fixed, semi-mobile, and mobile sensors were used to carry out surveys. Theoretical predictions provided by the COMFA thermal comfort model were compared with the subjective responses of the occupants. 65% of the model's results predict what people feel and tend to overestimate the real thermal perception, especially in warm climates such as Seville. These results can be helpful to redefine thermal comfort for climate change mitigation solutions assessment in public spaces.

Assessment of Outdoor Thermal Comfort in Urban Public Space, during the Hottest Period in Annaba City, Algeria

In this study; the outdoor thermal comfort of the users of two urban plazas with different morphologies in Annaba city, Algeria, have been evaluated. First, field measurements of the microclimatic parameters took place; namely the air temperature and the relative humidity in the two urban plazas, during hot days. Then, these measurements were compared with the results of the numerical simulations carried out by ENVI-met software in order to validate the model. The outdoor thermal comfort was evaluated by microclimatic measurements as well as a questionnaire survey consisting of interviews during the measurement days. The main objective was to determine the neutral Physiological Equivalent Temperature (PET) and to examine the influence of urban microclimatic conditions on the subjective thermal perception of people, as well as to compare it with different indexes of thermal comfort. Hence, the aim was to compare the microclimatic parameters of the two plazas, with and without vegetation and to see their impact on the thermal comfort indices. The results show that there is a difference between the two morphologies. Moreover, vegetation and urban morphology influence the neutral values of the thermal comfort indices.

Improving children's outdoor thermal comfort: A field study in China's severely cold regions

This study used meteorological monitoring, subjective thermal perception surveys, and activity records to explore the factors that affect children's outdoor thermal comfort in China's severely cold regions. The Universal Thermal Climate Index (UTCI) was used to determine children's thermal benchmarks and calendar, based on which a strategy to improve thermal comfort was proposed. Results showed (1) significant differences in solar radiation and wind speed, but not in air temperature and relative humidity between different areas. (2) Different Microclimate parameters affected children's thermal perception in different seasons: solar radiation (G) in winter, air temperature (Ta) in summer. (3) Children tolerate the UTCI changes in winter than in summer. (4) Children's neutral UTCI in winter and summer were 9.7 °C and 17.6 °C, respectively, and its ranges were 2.3–17.1 °C and 13.6–21.7 °C, respectively. The thermal acceptability range by 80% of the interviewed children was 2.1–16.3 °C. (5) Based on these results, a thermal comfort improvement on two dimensions—children and the environment—was implemented. This study enriches basic research on children's outdoor thermal comfort and provides a reference for the construction of urban child-friendly spaces.

Influence of topical menthol gel on thermoregulation and perception while walking in the heat.

Menthol is known to elicit opposing thermoregulatory and perceptual alterations during intense exercise. The current purpose was to determine the thermoregulatory and perceptual effects of topical menthol application prior to walking in the heat. Twelve participants walked (1.6m s-1, 5% grade) for 30min in the heat (38°C, 60% relative humidity) with either a 4% menthol or control gel on the upper (shoulder to wrist) and lower (mid-thigh to ankle) limbs. Skin blood flow (SkBF), sweat (rate, composition), skin conductivity, heart rate, temperature (skin, core), and thermal perception were measured prior to and during exercise. Skin conductivity expressed as time to 10, 20, 30, and 40 µS was delayed due to menthol (559 ± 251, 770 ± 292, 1109 ± 301, 1299 ± 335s, respectively) compared to the control (515 ± 260, 735 ± 256, 935 ± 300, 1148 ± 298s, respectively, p = 0.048). Sweat rate relative to body surface area was lower due to menthol (0.55 ± 0.16 L h-1 m(2)-1) than the control (0.64 ± 0.16 L h-1 m(2)-1, p = 0.049). Core temperature did not differ at baseline between the menthol (37.4 ± 0.3°C) and control (37.3 ± 0.4°C, p = 0.298) but was higher at 10, 20, and 30 min due to menthol (37.5 ± 0.3, 37.7 ± 0.2, 38.1 ± 0.3°C, respectively) compared to the control (37.3 ± 0.4, 37.4 ± 0.3, 37.7 ± 0.3°C, respectively, p < 0.05). The largest rise in core temperature from baseline was at 30min during menthol (0.7 ± 0.3°C) compared to the control (0.4 ± 0.2°C, p = 0.004). Overall, the menthol treatment was perceived cooler, reaching "slightly warm" whereas the control treatment reached "warm" (p < 0.001). Menthol application to the limbs impairs whole-body thermoregulation while walking in the heat despite perceiving the environment as cooler.

Evoking natural thermal perceptions using a thin-film thermoelectric device with high cooling power density and speed.

Multimodal sensory feedback from upper-limb prostheses can increase their function and usability. Here we show that intuitive thermal perceptions during cold-object grasping with a prosthesis can be restored in a phantom hand through targeted nerve stimulation via a wearable thin-film thermoelectric device with high cooling power density and speed. We found that specific regions of the residual limb, when thermally stimulated, elicited thermal sensations in the phantom hand that remained stable beyond 48 weeks. We also found stimulation sites that selectively elicited sensations of temperature, touch or both, depending on whether the stimulation was thermal or mechanical. In closed-loop functional tasks involving the identification of cold objects by amputees and by non-amputee participants, and compared with traditional bulk thermoelectric devices, the wearable thin-film device reliably elicited cooling sensations that were up to 8 times faster and up to 3 times greater in intensity while using half the energy and 1/600th the mass of active thermoelectric material. Wearable thin-film thermoelectric devices may allow for the non-invasive restoration of thermal perceptions during touch.

Studying the load of composite brake pads under high-temperature impact from the rolling surface of wheels

The object of the research is the processes of thermal stress, perception and redistribution of loads by the brake composite pad during braking of the car in operation. In the current conditions, wedge-dual wear of composite brake pads is observed in the braking systems of freight cars, the feature of which is the deterioration of the braking efficiency of freight trains. With this type of wear, both an increase in the load on the brake pad and an "underuse" of the amount of pressure on it can occur. A comprehensive thermal calculation was carried out for composite brake pads with uniform and wedge-dual wear. The results of the calculation showed that the amount of pressure on an abnormally worn pad is 23.3 % less than that acting on a pad with nominal values. It has been proven that the change in the pressure force on the composite pad with different values of the wear parameters during braking leads to a change in the braking force that occurs between the wheel and the rail during braking. The calculation of the strength of the composite brake pad with wedge-dual wear was carried out. The obtained results will make it possible to develop measures to modernize the elements of the brake lever transmission of freight cars. The field of practical use of the obtained results is car-building enterprises. The conditions for the practical use of the results are the brake lever transmissions of carriages of cars with a gauge of 1520 mm. The conducted studies prove the negative impact of wedge-dual wear not only on braking efficiency, but also on the strength of brake pads. This makes it necessary to create measures aimed at its elimination, which will contribute to increasing the level of train traffic safety and significantly reducing the operational costs of maintaining freight cars

A socio-cultural perspective to semi-outdoor thermal experience and restorative benefits – Comparison between Chinese and Australian cultural groups

Thermal experiences in outdoor and semi-outdoor environments contribute significantly to the holistic experience of nature and its restorative benefits. Culture may be a significant factor influencing the large variations of human thermal perception in semi-outdoor and outdoor environments. This research aims to compare the differences in thermal pleasure, adaptive behaviours, and restorative benefits between two cultural groups, Chinese and Australian, undergoing identical exposures in semi-outdoor environments. Pretest-posttest experiments were conducted in climate chambers with 19 Chinese and 19 Australian participants. A multisensory immersive Virtual Reality method was adopted for the simulation of two semi-outdoor environmental scenarios, one providing only direct sunlight exposure and the other including the adaptive opportunity for subjects to select between direct sunlight or shade. When exposed to the sunlight-only scenario, most of the Chinese participants felt thermally unpleasant and engaged in sunlight avoidance behaviours, while majority of the Australian participants felt thermally pleasant and engaged in sunlight maximising behaviours. There were also significant differences in restorative benefits. Moreover, access to shade as an adaptive opportunity can potentially reduce cultural differences in thermal pleasure and restorative benefits resulting from outdoor exposures. Different notions of skin beauty between Chinese and Australian cultural groups (fair vs suntanned skin tone) may have contributed to divergent environmental attitudes regarding sunlight exposure, resulting in different thermal pleasure responses and adaptive behavioural patterns. The importance of culture-specific and inclusive design should be promoted by implementing adaptive design strategies to satisfy the diverse thermal preferences of semi-outdoor and outdoor users.

Outdoor thermal perception and adaptation of immigrants from cold climates to hot arid climate

This study examined the long-term thermal perception and adaptation to a hot and arid climate of immigrants from cold regions as compared to native-born residents. The study was conducted in the desert city of Beer Sheva, Israel, population 220,000 inhabitants, including 50,000 immigrants from cold climates of Eastern Europe and Central Asia. Climatic measurements were made in winter and summer during 2010–2015 in various outdoor environments in the city, accompanied by questionnaire surveys including 2863 valid responses. Results showed that female immigrants were the most tolerant to the winter cold thermal conditions and their lower limit of neutral temperature was 3–4.5 °C PET lower than the other groups. During the summer, the difference in thermal sensation between genders and origins became negligible above 35 °C PET. The 90% Thermal Acceptability Range (TAR) for the winter was 13–22 °C PET for female immigrants and 17–24 °C PET for male native-born. In summer, the TAR upper limit for all groups was similar. Clothing insulation played an important role, where female immigrants usually used higher clothing insulation than natives. Immigrants from cold climatic backgrounds achieved long-term thermal adaption to the cold arid thermal conditions, and to the hot, arid climatic conditions by adapting behavioral thermal adjustment.

Effect of change rates and directions of air temperature ramps on thermal responses of occupants under warm summer conditions

Understanding thermal comfort in dynamic environments is vital for developing various air temperature control strategies that consider energy flexibility. However, studies on the quantitative effects of air-temperature change rates and directions on human thermal responses in thermal environments with temperature ramps (TRs) are limited. In this study, 22 sex-balanced young adults were recruited to investigate the thermal perceptions and physiological responses to room air TRs at rates of 0.10–0.30 °C/min in a climate chamber. The results revealed that the air temperature change direction had no effect on the mean skin temperature (Tskin) but significantly affected the thermal sensation vote (TSV), that is, the TSV was approximately 0.5 scales lower when the temperature was decreasing than when it was increasing (P < 0.05). Moreover, the slow change rates of Tskin within the range of ±0.07 °C/min had no significant effect on dynamic TSV, unlike that in step-change environments with higher change rates. The head was the most thermally sensitive body part with the highest TSV/Tskin values and change rates of Tskin (up to ±0.08 °C/min) in warm TR environments. In most cases, the thermal response of limbs was delayed. The thermal experience and adaptation levels of occupants may play essential roles in thermal perceptions within TR environments. Preliminary thermal comfort models suitable for hot summer climates were proposed in this study, which could be used in TR control strategies, such as intermittent cooling or demand response control.

The influence of virtual environment on thermal perception: physical reaction and subjective thermal perception on outdoor scenarios in virtual reality.

Positive thermal perception can affect users' climate-controlling behavior, indirectly reducing a building's operational carbon emissions. Studies show that some visual elements, such as window sizes and light colors, can influence thermal perception. However, until recently there has been little interest in the interaction of thermal perception and outdoor visual scenarios or natural elements like water or trees, and little quantitative evidence has been found associating visual natural elements and thermal comfort. This experiment explores and quantifies the extent to which visual scenarios outdoors affect thermal perception. The experiment used a double-blind clinical trial. All tests were done in a stable laboratory environment to eliminate temperature changes, and scenarios were shown through a virtual reality (VR) headset. Forty-three participants were divided into three groups randomly, separately watched VR-outdoor scenarios with natural elements, VR-indoor scenarios, and a control scenario of the real laboratory, then finished a subjective questionnaire conducted to evaluate their thermal, environmental, and overall perceptions while their physical data (heart rate, blood pressure, pulse) was real-time recorded. Results show that visual scenarios could significantly influence thermal perception (Cohen's d between groups > 0.8). Significant positive correlations were found between key thermal perception index, thermal comfort, and visual perception indexes including visual comfort, pleasantness, and relaxation (all PCCs ≤ 0.01). Outdoor scenarios, with better visual perception, rank higher average scores (M ± SD = 1.0 ± 0.7) in thermal comfort than indoor groups (average M ± SD = 0.3 ± 1.0) while the physical environment remains unchanged. This connection between thermal and environmental perception can be used in building design. By being visually exposed to pleasing outdoor environments, the positive thermal perception will increase, and thus reduce building energy consumption. Designing positive visual environments with outdoor natural elements is not only a requirement for health but also a feasible path toward a sustainable net-zero future.