Drivers of diversity in human thermal perception - A review for holistic comfort models

Role of thermosensitive transient receptor potential (TRP) channels in thermal preference of male and female mice

Transient Receptor Potential (TRP) ion channels are important for sensing environmental temperature. In rodents, TRPV4 senses warmth (25-34 °C), TRPV1 senses heat (>42 °C), TRPA1 putatively senses cold (<17 °C), and TRPM8 senses cool-cold (18-26 °C). We investigated if knockout (KO) mice lacking these TRP channels exhibited changes in thermal preference. Thermal preference was tested using a dual hot-cold plate with one thermoelectric surface set at 30 °C and the adjacent surface at a temperature of 15-45 °C in 5 °C increments. Blinded observers counted the number of times mice crossed through an opening between plates and the percentage of time spent on the 30 °C plate. In a separate experiment, observers blinded as to genotype also assessed the temperature at the location on a thermal gradient (1.83 m, 4-50 °C) occupied by the mouse at 5- or 10-min intervals over 2 h. Male and female wildtype mice preferred 30 °C and significantly avoided colder (15-20 °C) and hotter (40-45 °C) temperatures. Male TRPV1KOs and TRPA1KOs, and TRPV4KOs of both sexes, were similar, while female WTs, TRPV1KOs, TRPA1KOs and TRPM8KOs did not show significant thermal preferences across the temperature range. Male and female TRPM8KOs did not significantly avoid the coldest temperatures. Male mice (except for TRPM8KOs) exhibited significantly fewer plate crossings at hot and cold temperatures and more crossings at thermoneutral temperatures, while females exhibited a similar but non-significant trend. Occupancy temperatures along the thermal gradient exhibited a broad distribution that shrank somewhat over time. Mean occupancy temperatures (recorded at 90-120 min) were significantly higher for females (30-34 °C) compared to males (26-27 °C) of all genotypes, except for TRPA1KOs which exhibited no sex difference. The results indicate (1) sex differences with females (except TRPA1KOs) preferring warmer temperatures, (2) reduced thermosensitivity in female TRPV1KOs, and (3) reduced sensitivity to cold and innocuous warmth in male and female TRPM8KOs consistent with previous studies.

Thermal stress and hospital admissions for cardiorespiratory disease in Brazil

The growing body of scientific literature underscores the intricate relationship between meteorological conditions and human health, particularly in the context of extreme temperatures. However, conventional temperature-centric approaches often fall short in capturing the complexity of thermal stress experienced by individuals. Temperature alone, as a metric, fails to encompass the entirety of the thermal stress individuals face, necessitating a more nuanced understanding. In response to this limitation, climatologists have devised thermal indices-composite measures meticulously crafted to reflect the intricate interplay of meteorological factors influencing human perception of temperature. Recognizing the inadequacy of simplistic temperature-focused methodologies, our study aims to address the multifaceted nature of thermal stress. In this study, we explored the association between thermal indices and hospital admissions for circulatory and respiratory diseases in Brazil. We used an extensive dataset spanning 11 years (2008-2018) from the Brazilian Ministry of Health, encompassing a total of 23,791,093 hospitalizations for circulatory and respiratory diseases. We considered four distinct thermal indices-Discomfort Index (DI), Net Effective Temperature (NET), Humidex (H), and Heat Index (HI). We used an extension of the two-stage design with a case time series to assess this relationship. In the first stage, we applied a distributed lag non-linear modeling framework to create a cross-basis function. We next applied quasi-Poisson regression models adjusted by time-varying confounders. In the second stage, we applied meta-analysis with random effects to estimate the national relative risk (RR). Our findings suggest robust variations among the thermal indices under examination. These variations underscore the intricate nature of associations between temperature and health, with each index capturing distinct aspects of thermal conditions. Our results indicate that extreme thermal conditions, both at the low and high ends, are associated with increased risks of hospital admissions. The diverse impact observed among different indices emphasizes the complex interplay between various meteorological factors and their specific physiological consequences. This underscores the necessity for a comprehensive comprehension of temperature metrics to guide precise public health interventions, recognizing the multifaceted nature of temperature-health relationships.

Stress influence on real-world driving identified by monitoring heart rate variability and morphologic variability of electrocardiogram signals: the case of intercity roads

Objectives. This study examines which of the heart rate variability (HRV) and morphologic variability (MV) metrics may have the highest accuracy in different stress detection during real-world driving. Methods. The cross-sectional study was carried out among 93 intercity mini-bus male drivers aged 22-67 years. The Trillium 5000 Holter Recorder and GARMIN Virb Elite camera were used to determine heart rate and vehicle speed measurements along the path, respectively. We considered the HRV and MV metrics of electrocardiogram (ECG) signals including the mean RR interval (mRR), mean heart rate (mHR), normalized low-frequency spectrum (nLF), normalized high-frequency spectrum (nHF), normalized very low-frequency spectrum (nVLF), difference of normalized low-frequency spectrum and normalized high-frequency spectrum (dLFHF), and sympathovagal balance index (SVI). Results. The analysis showed that the HRV metrics mHR, mRR, nVLF, nLF, nHF, dLFHF and SVI are effective in mental stress detection while driving as compared to rest time. We obtained a high accuracy of stress detection for MV metrics as compared to the traditional HRV analysis, of approximately 92%. Conclusions. Our findings indicate that driver stress could be detected with an accuracy of 92% using MV metrics as an accurate physiological index of the driver's state.

Physiological responses to 9 hours of heat exposure in young and older adults. Part III: Association with self-reported symptoms and mood state

Older adults are at greater risk of heat-related morbidity and mortality during heat waves, which is commonly linked to impaired thermoregulation. However, little is known about the influence of increasing age on the relation between thermal strain and perceptual responses during daylong heat exposure. We evaluated thermal and perceptual responses in 20 young (19-31 yr) and 39 older adults (20 with hypertension and/or type 2 diabetes; 61-78 yr) resting in the heat for 9 h (heat index: 37°C). Body core and mean skin temperature areas under the curve (AUC, hours 0-9) were assessed as indicators of cumulative thermal strain. Self-reported symptoms (68-item environmental symptoms questionnaire) and mood disturbance (40-item profile of mood states questionnaire) were assessed at end-heating (adjusted for prescores). Body core temperature AUC was 2.4°C·h [1.0, 3.7] higher in older relative to young adults (P < 0.001), whereas mean skin temperature AUC was not different (-0.5°C·h [-4.1, 3.2] P = 0.799). At end-heating, self-reported symptoms were not different between age groups (0.99-fold [0.80, 1.23], P = 0.923), with or without adjustment for body core or mean skin temperature AUC (both P ≥ 0.824). Mood disturbance was 0.93-fold [0.88, 0.99] lower in older, relative to young adults (P = 0.031). Older adults with and without chronic health conditions experienced similar thermal strain, yet those with these conditions reported lower symptom scores and mood disturbance compared with young adults and their age-matched counterparts (all P ≤ 0.026). Although older adults experienced heightened thermal strain during the 9-h heat exposure, they did not experience greater self-reported symptoms or mood disturbance relative to young adults.NEW & NOTEWORTHY Despite experiencing greater cumulative thermal strain during 9 h of passive heat exposure, older adults reported similar heat-related symptoms and lower mood disturbance than young adults. Furthermore, self-reported symptoms and mood disturbance were lower in older adults with common age-associated health conditions than young adults and healthy age-matched counterparts. Perceptual responses to heat in older adults can underestimate their level of thermal strain compared with young adults, which may contribute to their increased heat vulnerability.

Neural correlates of thermal stimulation during active touch

Introduction

Thermal feedback technologies have been explored in human-computer interaction to provide secondary information and enhance the overall user experience. Unlike fast-response haptic modalities such as vibration and force feedback, the human brain's processes associated with thermal feedback are not fully understood.

Methods

In this study, we utilize electroencephalography (EEG) brain imaging to systematically examine the neural correlates associated with a wide range of thermal stimuli, including 9, 15, 32, and 42°C, during active touch at the fingertip. A custom experimental setup is developed to provide thermal stimulation at the desirable temperature levels. A total of 30 participants are recruited to experience the four levels of thermal stimulation by actively touching a thermal stimulation unit with the index finger while recording brain activities via EEG. Time-frequency analysis and power spectral density (PSD) of the EEG data are utilized to analyze the delta, theta, alpha, beta, and gamma frequency bands.

Results

The results show that the delta, theta, and alpha PSDs of 9 and 15°C stimuli are significantly higher than the PSDs of 32 and 42°C in the right frontal area during the early stage of the stimulation, from 282 ms up to 1,108 ms (One-way ANOVA test, Holm-Bonferroni correction, p < 0.05). No significant differences in PSDs are found between 9 and 15°C thermal stimuli or between 32 and 42°C thermal stimuli.

Discussion

The findings of this study inform the development of thermal feedback system in human-computer interaction.

Sex differences in thermal sensitivity and perception: Implications for behavioral and autonomic thermoregulation

Temperature sensitive receptors in the skin and deep body enable the detection of the external and internal environment, including the perception of thermal stimuli. Changes in heat balance require autonomic (e.g., sweating) and behavioral (e.g., seeking shade) thermoeffector initiation to maintain thermal homeostasis. Sex differences in body morphology can largely, but not entirely, account for divergent responses in thermoeffector and perceptual responses to environmental stress between men and women. Thus, it has been suggested that innate differences in thermosensation may exist between men and women. Our goal in this review is to summarize the existing literature that investigates localized and whole-body cold and heat exposure pertaining to sex differences in thermal sensitivity and perception, and the interplay between autonomic and behavioral thermoeffector responses. Overall, it appears that local differences in thermal sensitivity and perception are minimized, yet still apparent, when morphological characteristics are well-controlled. Sex differences in the early vasomotor response to environmental stress and subsequent changes in blood flow likely contribute to the heightened thermal awareness observed in women. However, the contribution of thermoreceptors to observed sex differences in thermal perception and thermoeffector function is unclear, as human studies investigating these questions have not been performed.

Thermoregulation and thermal sensation during whole-body water immersion at different water temperatures in healthy individuals: A scoping review

BACKGROUND

Severe thermal discomfort may increase risk of drowning due to hypothermia or hyperthermia from prolonged exposure to noxious water temperatures. The importance of using a behavioral thermoregulation model with thermal sensation may predict the thermal load that the human body receives when exposed to various immersive water conditions. However, there is no thermal sensation "gold standard" model specific for water immersion. This scoping review aims to present a comprehensive overview regarding human physiological and behavioral thermoregulation during whole-body water immersion and explore the feasibility for an accepted defined sensation scale for cold and hot water immersion.

METHODS

A standard literary search was performed on PubMed, Google Scholar, and SCOPUS. The words "Water Immersion," "Thermoregulation," "Cardiovascular responses" were used either as independent searched terms and MeSH terms (Medical Subject Headings) or in combination with other text words. The inclusion criteria for clinical trials terms to thermoregulatory measurements (core or skin temperature), whole-body immersion, 18-60 years old and healthy individuals. The prementioned data were analyzed narratively to achieve the overall study objective.

RESULTS

Twenty-three published articles fulfilled the review inclusion/exclusion criteria (with nine measured behavioral responses). Our outcomes illustrated a homogenous thermal sensation in a variety of water temperatures ranges, that was strongly associated with thermal balance, and observed different thermoregulatory responses. This scoping review highlights the impact of water immersion duration on human thermoneutral zone, thermal comfort zone, and thermal sensation.

CONCLUSION

Our findings enlighten the significance of thermal sensation as a health indicator for establishing a behavioral thermal model applicable for water immersion. This scoping review provides insight for the needed development of subjective thermal model of thermal sensation in relation to human thermal physiology specific to immersive water temperature ranges within and outside the thermal neutral and comfort zone.

Analysis of the heat- and cold-related cardiovascular mortality in an urban mediterranean environment through various thermal indices

During the last decades the effects of thermal stress on public health have been a great concern worldwide. Thermal stress is determined by air temperature in combination with other meteorological parameters, such as relative humidity and wind speed. The present study is focused on the Mediterranean city of Thessaloniki, Greece and it aims to explore the association between thermal stress and mortality from cardiovascular diseases, using both air temperature and other thermal indices as indicators. For that, an over-dispersed Poisson regression function was used, in combination with distributed lag non-linear models, in order to capture the delayed and nonlinear effects of temperature. Our results revealed a reverse J-shaped exposure-response curve for the total population and females and a U-shaped association for males. In all cases examined, the minimum mortality temperature was identified around the 80th percentile of each distribution. It is noteworthy that despite the fact that the highest risks of cardiovascular mortality were estimated for exposure to extreme temperatures, moderate temperatures were found to cause the highest burden of mortality. On the whole, our estimations demonstrated that the population in Thessaloniki is more susceptible to cold effects and in regard with gender, females seem to be more vulnerable to ambient thermal conditions.

Women have a greater cardiac vagal withdrawal to heat stress compared to men

The heated environment shifts the sympatho-vagal balance toward sympathetic predominance and vagal withdrawal. Women's heart is more reliant on vagal autonomic control, while men's heart is more dependent on sympathetic control. However, sex differences in cardiovascular autonomic responses to heat stress remain unknown. We aimed to investigate the cardiovascular autonomic regulation under heat stress between sexes. Thirty-two young participants (27 ± 4 years old; 16 women) were enrolled in a single visit, resting for 30min at baseline (thermal reference condition TC; ∼24°C) and 30min under a heated environment (HOT; ∼38°C). Blood pressure (BP), skin temperature, electrocardiogram, and respiratory oscillations were continuously recorded. The heart rate variability (HRV) was assessed by spectral analysis (low-frequency [LFnu; sympathetic and vagal] and high-frequency [HFnu; vagal]), and symbolic analysis (0 V% [sympathetic] and 2UV%, and 2LV% [vagal]). The spontaneous baroreflex sensitivity (BRS) was calculated by the gain between BP and R-R within the LF band (αLF). The estimated maximal aerobic capacity and body surface area were employed as covariates in sex comparisons. The effects of HOT were the following: 1) Women have a greater cardiac vagal withdrawal to heat stress compared to men; 2) Sex differences on cardiac autonomic response to heat stress exist after controlling for the effect of estimated physical fitness and body surface area. Therefore, heat stress provokes a higher vagal withdrawal to the heart in women compared to men. It could be attributed to sex per se since significant differences between men and women were not modified after covariate analysis.

A systematic approach to quantify the influence of indoor environmental parameters on students' perceptions, responses, and short-term academic performance

Several studies found that classrooms' indoor environmental quality (IEQ) can positively influence in-class activities. Understanding and quantifying the combined effect of four indoor environmental parameters, namely indoor air quality and thermal, acoustic, and lighting conditions on people is essential to create an optimal IEQ. Accordingly, a systematic approach was developed to study the effect of multiple IEQ parameters simultaneously. Methods for measuring the IEQ and students' perceived IEQ, internal responses, and academic performance were derived from literature. Next, this systematic approach was tested in a pilot study during a regular academic course. The perceptions, internal responses, and short-term academic performance of participating students (n = 163) were measured. During the pilot study, the IEQ of the classrooms varied slightly. Significant associations (p < 0.05) were observed between these natural variations and students' perceptions of the thermal environment and indoor air quality. These perceptions were significantly associated with their physiological and cognitive responses (p < 0.05). Furthermore, students' perceived cognitive responses were associated with their short-term academic performance (p < 0.01). The observed associations confirm the construct validity of the systematic approach. However, its validity for investigating the influence of lighting remains to be determined.

Studying the Indoor Environment and Comfort of a University Laboratory: Air-Conditioning Operation and Natural Ventilation Used as a Countermeasure against COVID-19

In this study, the indoor air quality and thermal environment of a university facility were analyzed when an air conditioner was operated and natural ventilation was provided; the most effective natural ventilation method was also evaluated. The research conditions were established by adjusting the temperature of the air conditioner, and frequency of window openings every hour. The area around the windows that is open for natural ventilation was easily affected by outdoor air temperature and humidity. However, since the air conditioner was operating, there was only a brief period during which the environment was uncomfortable. Therefore, the participants in the questionnaire survey expressed neutrality or slight satisfaction for the thermal environment of the entire space. Setting the room temperature to 25 °C in summer was highly comfortable and generated a satisfactory indoor thermal environment. When the room temperature was set to 20 °C in winter, the thermal comfort level was higher than in the other conditions. Providing natural ventilation for 5 min every 30 min was determined to be effective in maintaining an indoor CO2 concentration of 1000 ppm or less. Facilitating natural ventilation for 10 min every 60 min allowed the entry of a large amount of fresh air; however, due to the extended period in which the windows and doors were closed, there were instances when the indoor CO2 concentration exceeded 1000 ppm. Therefore, providing frequent natural ventilation with short time intervals is effective for improving indoor air quality.

Combining adaptive and heat balance models for thermal sensation prediction: A new approach towards a theory and data-driven adaptive thermal heat balance model

The adaptive thermal heat balance (ATHB) framework introduced a method to account for the three adaptive principals, namely physiological, behavioral, and psychological adaptation, individually within existing heat balance models. This work presents a more detailed theoretical framework together with a theory-driven empirical determination toward a new formulation of the ATHB_PMV . The empirical development followed a rigor statistical process known from machine learning approaches including training, validation, and test phase and makes use of a subset (N = 57 084 records) of the ASHRAE Global Thermal Comfort Database. Results show an increased predictive performance among a wide range of outdoor climates, building types, and cooling strategies of the buildings. Furthermore, individual findings question the common believe that psychological adaptation is highest in naturally ventilated buildings. The framework offers further opportunities to include a variety of context-related variables as well as personal characteristics into thermal prediction models, while keeping mathematical equations limited and enabling further advancements related to the understanding of influences on thermal perception.

Functional links between thermoregulation and sleep in children with neurodevelopmental and chronic health conditions

The bi-directional relationship between sleep and wake is recognized as important for all children. It is particularly consequential for children who have neurodevelopmental disorders (NDDs) or health conditions which challenge their sleep and biological rhythms, and their ability to maintain rhythms of participation in everyday activities. There are many studies which report the diverse reasons for disruption to sleep in these populations. Predominantly, there is focus on respiratory, pharmaceutical, and behavioral approaches to management. There is, however, little exploration and explanation of the important effects of body thermoregulation on children's sleep-wake patterns, and associated behaviors. Circadian patterns of sleep-wake are dependent on patterns of body temperature change, large enough to induce sleep preparedness but remaining within a range to avoid sleep disturbances when active thermoregulatory responses against heat or cold are elicited (to maintain thermoneutrality). Additionally, the subjective notion of thermal comfort (which coincides with the objective concept of thermoneutrality) is of interest as part of general comfort and associated behavioral responses for sleep onset and maintenance. Children's thermoregulation and thermal comfort are affected by diverse biological functions, as well as their participation in everyday activities, within their everyday environments. Hence, the aforementioned populations are additionally vulnerable to disruption of their thermoregulatory system and their capacity for balance of sleep and wakefulness. The purpose of this paper is to present hitherto overlooked information, for consideration by researchers and clinicians toward determining assessment and intervention approaches to support children's thermoregulation functions and promote their subjective thermal comfort, for improved regulation of their sleep and wake functions.

Neuroimaging of pleasantness and unpleasantness induced by thermal stimuli

Functional brain imaging techniques provide unique insight into the process of human thermal regulation and its associated hedonics. Similar neuroimaging techniques have predominantly focused on the neural characterization of thermal response separately from hedonics. In this instance, there is a gap in the understanding of hedonics related to regional brain activations. Responses to localized, thermal stimuli are yet to be characterized, but it would appear that thermoregulatory regions are widely distributed throughout the hemispheres of the human brain. The distributed nature of neural activations related to temperature responses is consistent with multiple related functions contributing to thermoregulation. Estimating hedonics of thermal stimulation includes a cognitive process that could potentially interfere with identifying activation specific to hedonics. A future challenge for brain imaging studies is to more accurately dissect the functional neuroanatomy of thermoregulation and related hedonics in hemispheric regions.

Application areas and effects of aquatic therapy WATSU - A survey among practitioners

INTRODUCTION

WATSU (WaterShiatsu) is a treatment administered in warm water. The present study investigated if and how frequently scientifically studied application areas and effects of WATSU occur in practice, whether similar effectiveness of WATSU is observed in trials and practice, and whether practitioners can contribute additional application areas and effects of WATSU.

METHODS

Application areas and effects of WATSU reported in a recent systematic review were extracted verbatim to be assessed in a worldwide multilingual cross section online survey, generating quantitative and qualitative data. A pre-test and retest were conducted to ensure quality and evaluate the questionnaire's psychometric properties.

RESULTS

Answers of 191 respondents were processed. All proposed 26 application areas and 20 effects were confirmed, each with relatively high ratings of observed effectiveness of WATSU. WATSU was frequently applied in healthy individuals (including during pregnancy), and individuals in various pain- (e.g., low back pain, neck pain, myofascial pain, fibromyalgia) and stress-related (e.g., stress, depression, sleep disorders, fatigue, anxiety disorders) conditions. Frequently confirmed effects were physical relaxation, relief of physical tension, pain relief, increased mobility and flexibility, improved quality of life, spiritual experiences, and increased psychological health. Respondents contributed 73 additional application areas and effects (both, mental and physical) of WATSU.

CONCLUSIONS

Application areas and effects of WATSU are consistently employed practically and scientifically. Respondents' ratings of effectiveness of WATSU match tentative research efforts. WATSU is cautiously recommended for the use in pain- and stress-related conditions. Short- and long-term effectiveness of WATSU need to be evaluated in high level intervention studies.

Does thermal control improve visual satisfaction? Interactions between occupants' self-perceived control, visual, thermal, and overall satisfaction

Occupants' satisfaction had been researched independently related to thermal and visual stimuli for many decades showing among others the influence of self-perceived control. Few studies revealed interactions between thermal and visual stimuli affecting occupant satisfaction. In addition, studies including interactions between thermal and visual stimuli are lacking different control scenarios. This study focused on the effects of thermal and visual factors, their interaction, seasonal influences, and the degree of self-perceived control on overall, thermal, and visual satisfaction. A repeated-measures laboratory study with 61 participants running over two years and a total of 986 participant sessions was conducted. Mixed model analyses with overall satisfaction as outcome variable revealed that thermal satisfaction and visual satisfaction are the most important predictors for overall satisfaction with the indoor environment. Self-perceived thermal control served as moderator between thermal satisfaction and overall satisfaction. Season had slight influence on overall satisfaction. Random effects explained the highest amount of variance, indicating that intra- and interindividual differences in the ratings of satisfaction are more prevalent than study condition. Future building design and operation plans aiming at a high level of occupant satisfaction should consider personal control opportunities and take into account the moderating effect of control opportunities in multimodal interactions.

Human thermal perception and time of day: A review

The circadian clock regulates diurnal variations in autonomic thermoregulatory processes such as core body temperature in humans. Thus, we might expect that similar daily fluctuations also characterize human thermal perception, the ultimate role of which is to drive thermoregulatory behaviors. In this paper, we explore this question by reviewing experimental and observational thermal comfort investigations which include the "time of day" variable. We found only 21 studies considering this factor, and not always as their primary analysis. Due to the paucity of studies and the lack of a specific focus on time-of-day effects, the results are difficult to compare and appear on the whole contradictory. However, we observe a tendency for individuals to prefer higher ambient temperatures in the early evening as compared to the rest of the day, a result in line with the physiological decrease of the core body temperature over the evening. By drawing from literature on the physiology of thermoregulation and circadian rhythms, we outline some potential explanations for the inconsistencies observed in the findings, including a potential major bias due to the intensity and spectrum of the selected light conditions, and provide recommendations for conducting future target studies in highly-controlled laboratory conditions. Such studies are strongly encouraged as confirmed variations of human thermal perceptions over the day would have enormous impact on building operations, thus on energy consumption and occupant comfort. List of abbreviations: TSV: Thermal Sensation Vote; TCV: Thermal Comfort Vote; Tpref: Preferred Temperature; TA: Indoor Air Temperature; RH: Indoor Relative Humidity; Tskin: Skin Temperature; Tty: Tympanic Temperature; Tre: Rectal Temperature; Toral: Oral Temperature.

Exercise Performance and Thermoregulatory Responses of Elite Athletes Exercising in the Heat: Outcomes of the Thermo Tokyo Study

Objective

We examined the impact of simulated Tokyo 2020 environmental condition on exercise performance, thermoregulatory responses and thermal perception among Dutch elite athletes.

Methods

105 elite athletes from different sport disciplines performed two exercise tests in simulated control (15.9 ± 1.2 °C, relative humidity (RH) 55 ± 6%) and Tokyo (31.6 ± 1.0 °C, RH 74 ± 5%) environmental conditions. Exercise tests consisted of a 20-min warm-up (70% HR_max), followed by an incremental phase until volitional exhaustion (5% workload increase every 3 min). Gastrointestinal temperature (T_gi), heart rate, exercise performance and thermal perception were measured.

Results

Time to exhaustion was 16 ± 8 min shorter in the Tokyo versus the control condition (− 26 ± 11%, whereas peak power output decreased with 0.5 ± 0.3 W/kg (16 ± 7%). Greater exercise-induced increases in T_gi (1.8 ± 0.6 °C vs. 1.5 ± 0.5 °C, p < 0.001) and higher peak T_gi (38.9 ± 0.6 °C vs. 38.7 ± 0.4 °C, p < 0.001) were found in the Tokyo versus control condition. Large interindividual variations in exercise-induced increase in T_gi (range 0.7–3.5 °C) and peak T_gi (range 37.6–40.4 °C) were found in the Tokyo condition, with greater T_gi responses in endurance versus mixed- and skill-trained athletes. Peak thermal sensation and thermal comfort scores deteriorated in the Tokyo condition, with aggravated responses for power versus endurance- and mixed-trained athletes.

Conclusion

Large performance losses and T_gi increases were found among elite athletes exercising in simulated Tokyo conditions, with a substantial interindividual variation and significantly different responses across sport disciplines. These findings highlight the importance of an individual approach to optimally prepare athletes for safe and maximal exercise performance during the Tokyo Olympics.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01530-w.

Associations between Perceptions and Measures of Weather and Walking, United States-2015

INTRODUCTION

Weather can be a barrier to walking. Understanding how perceptions of weather as a barrier and measured temperature are associated with walking can inform monitoring and promotion strategies. The objective of this study is to examine the association between perceptions of weather as a barrier to walking and measured weather with the volume of leisure and transportation walking.

METHODS

The 2015 National Health Interview Survey (NHIS) assessed participation in and volume of walking (transportation, leisure) in the past week and frequency of reporting weather as a barrier to walking. Data were collected over the entire year. In 2019, we merged month-specific temperature data from the PRISM climate group with individual NHIS records. We examined associations using logistic (participation) and linear regression models (volume).

RESULTS

Participation in walking increased as frequency of reporting weather as a barrier to walking decreased, from 'almost always' (transportation: 23%, leisure: 42%) to 'a little of the time' (transportation: 40%, leisure: 67%). Among adults reporting walking, walking volume increased as frequency of reporting weather as a barrier decreased from 'almost always' (transportation: 51 min/week, leisure: 64 min/week) to 'never' (transportation: 69 min/week, leisure: 98 min/week). Month-specific temperature was significantly associated with leisure walking with lower participation at the lowest and highest temperature quintiles, although the strength of the association differed by frequency of reporting weather as a barrier.

CONCLUSIONS

In general, prevalence and volume of leisure and transportation walking decreased as the perception of weather as a barrier increased. Low and high temperature conditions were also associated with leisure walking participation, particularly among adults with increased perceptions of weather as a barrier. Our findings highlight the importance of including strategies to help adults overcome perceived and actual weather-related barriers in walking promotion efforts.

Summer Thermal Conditions in Outdoor Public Spaces: A Case Study in a Mediterranean Climate

Comfort in public spaces is essential to their attractiveness and continued role in improving human quality of life. Acceptable thermal conditions are determinant to ensuring users’ comfort. This study undertakes an assessment of three urban sites in Arouca, in the north of Portugal, using ENVI-met software. Simulations test the influence of pavement and façade covering material, vegetation, and site morphology. The climate of the region is classified as Mediterranean Csb, with rainy winters and dry and mildly warm summers. A typical summer day is considered. The results reveal that a combination of factors might lead to thermal discomfort even in this mild climate on an average day, mainly due to heat exchange by radiation. In addition, the impact of alterations to surface properties depends on the morphological characteristics of the site, e.g., high albedo of the pavement may lead to a decrease or an increase in mean radiant temperature, depending on the space. This variability is present in the effects observed at the studied sites. A high façade albedo always contributes, in these cases, to thermal discomfort. The conclusions of the present study highlight the importance of performing a specific study for each urban site whenever an intervention is to be planned.

Resilience of vernacular and modernising dwellings in three climatic zones to climate change

Climate change impacts buildings in multiple ways, including extreme weather events and thermal stresses. Rural India comprising 65% of the population is characterised by vernacular dwellings evolved over time to passively regulate and maintain comfortable indoors. Increasing modernization in rural habitations (transitions) evident from the ingress of modern materials and electro-mechanical appliances undermines the ability of building envelopes to passively regulate and maintain comfortable indoors. While such trends are deemed good for the economy, their underlying implications in terms of climate change have not been adequately examined. The current study evaluates the climate-resilience of vernacular dwellings and those undergoing transitions in response to three climate-change scenarios, viz, A1B (rapid economic growth fuelled by balanced use of energy sources), A2 (regionally sensitive economic development) and B1 (structured economic growth and adoption of clean and resource efficient technologies). The study examines dwellings characteristic to three rural settlements representing three major climate zones in India and involves both real-time monitoring and simulation-based investigation. The study is novel in investigating the impact of climate change on indoor thermal comfort in rural dwellings, adopting vernacular and modern materials. The study revealed higher resilience of vernacular dwellings in response to climate change.

Sex Differences in Thermal Comfort, Perception, Feeling, Stress and Focus During Exercise Hyperthermia

It is unclear whether men and women perceive thermal stress differently when changes in intestinal temperature (ΔTin) and metabolic heat production (MHprod) are matched between sexes during exercise hyperthermia. This study tested the hypothesis that females have enhanced sensitivity to comfort and perception of thermal stress during exercise hyperthermia in these conditions. We had 22 healthy active adults (11 males, 11 females; M age = 22.4 years, SD = 4.9; M height = 169 cm, SD = 7.6; M weight = 68.3 kg, SD = 13) exercise in random order, separated by at least three days at similar MHprod (M = 7.0 W/kg, SD = 1.5; p = 0.32) for 60 minutes on a cycle ergometer in cool (M = 24.0⁰C, SD = 0.0; M = 14.4%Rh, SD = 3.6) and hot (M = 42.3°C, SD = 0.2; M = 10-60%Rh) environments with a progressive increase in humidity conditions. We measured ΔTin, and thermal stress indices for sensation (TS), comfort (TC), pleasantness (TP), and stickiness (S), feeling (FS scale), stress (visual analogue stress scale, VAS), focus (F) and felt arousal (FAS scale). We examined environmental conditions as wet bulb globe temperatures (WBGT). Males and females had similar increases in ΔTin (ME: WBGT; p < 0.0001), and both groups reported increased TS and TC and decreased TP (ME: WBGT, p ≤ 0.01). However, females reported that TS, TC, and TP, felt hotter overall, more uncomfortable, and more unpleasant, compared to males (ME: Sex; p < 0.04). Overall, females felt worse and were more stressed compared to males (ME: Sex; p ≤ 0.05). Females also reported greater internal focus as WBGT increased compared to males (I: WBGT × Sex; p < 0.003). Knowing that females perceive thermal stress during exercise hyperthermia to be hotter, more uncomfortable, more unpleasant, and more stressful compared to males can help coaches/trainers plan different exercise routines for exercisers of both sexes.

Post-Occupancy Evaluation of Indoor Air Quality and Thermal Performance in a Zero Carbon Building

Maintaining a comfortable indoor environment throughout the year makes up the main part of energy consumption caused by people’s use of buildings. In recent years, China has started to integrate sustainable technologies into green building design and construction. However, some post-occupancy reports on certified buildings revealed that such integration has been perceived to prioritize energy savings over comfort. This paper aims to investigate the ability of the first Chinese zero carbon building to maintain comfortable and healthy indoor conditions in the summer season. The research implements a combination of occupant survey and on-site measurements to evaluate the occupants’ perception of the indoor environment quality (IEQ) and benchmark the measurements against relevant standards. The results from this study show that the mean summer indoor temperature was 0.9 °C above the standard limit, while on average, occupants gave a positive score to the indoor thermal environment. High contentment with the building acoustics was reported by users and supported by sensors measurements meeting the standard values. The illuminance levels were mainly maintained high with the exception of the light in one of the studied zones. Analyzing the data on occupants experiencing sick building syndromes revealed that 45.8% of respondents experienced at least one of the symptoms.

Effect of Thermal, Acoustic and Air Quality Perception Interactions on the Comfort and Satisfaction of People in Office Buildings

Current research on human comfort has identified a gap in the investigation of multi-domain perception interactions. There is a lack of understanding the interrelationships of different physio-socio-psychological factors and the manifestation of their contextual interactions into cross-modal comfort perception. In that direction, this study used data from a post occupancy evaluation survey (n = 26), two longitudinal comfort studies (n = 1079 and n = 52) and concurrent measurements of indoor environmental quality factors (one building) to assess the effect of thermal, acoustic and air quality perception interactions on comfort and satisfaction of occupants in three mixed-mode university office buildings. The study concluded that thermal sensation (TSV) is associated with both air quality (ASV) and noise perception (NSV). The crossed effect of the interaction of air quality and noise perception on thermal sensation was not evident. The key finding was the significant correlation of operative temperature (Top) with TSV as expected, but also with noise perception and overall acoustic comfort. Regarding the crossed main effects on thermal sensation, a significant effect was found for the interactions of (1) Top and (2) sound pressure levels (SPL30) with air quality perception respectively. Most importantly, this study has highlighted the importance of air quality perception in achieving occupants’ comfort and satisfaction with office space.

Health and Habitability in the Solar Decathlon University Competitions: Statistical Quantification and Real Influence on Comfort Conditions

Medicine and architecture are disciplines with the main objectives of satisfying the fundamental needs of human beings: health, comfort, well-being, safety, and ensuring an acceptable quality of life in a sustainable habitat. In both areas of knowledge, the advances and the most innovative proposals in the fields of research and teaching are focused on transversal knowledge and the use of learning methods through problem solving (learning by doing). The student competitions called "Solar Decathlon" are focused on the development of these concepts, in which prototypes of sustainable and, as far as possible, healthy social housing are tested. In these university competitions, the design of energy-efficient and comfortable living environments that contribute to the health of the occupants are encouraged; however, the methodology for evaluating the "comfort conditions" stipulated in the competition rules considers only parameters that can be monitored by sensors. For this article, the prototypes presented by the "Solar Decathlon Team of the University of Seville" to the editions of said competition held in Latin America and Europe (in 2015 and 2019, respectively) are being studied. The present research starts from the fact that the unique consideration of measurable indices (such as temperature, humidity, etc.), is clearly insufficient when it comes to evaluating the real conditions of habitability and comfort that a domestic architectural space presents. For this reason, a theoretical-practical analysis is carried out by means of surveys, with the final objective of determining a methodology for evaluating comfort-complementary to that of the competition-which assesses other relevant issues and which, in short, takes into account the repercussion on people's health. From our analysis, we conclude that at least these two methodologies should be used to evaluate comfort because they are individually considered incomplete in terms of the data provided by each one of them. The survey-based methodology provides complementary information on comfort and health that could be taken into account in future editions of Solar Decathlon.

Predictive value of three thermal comfort indices in low temperatures on cardiovascular morbidity in the Iberian peninsula

The natural environment has been considered an important determinant of cardiovascular morbidity. This work seeks to assess the impact of the winter thermal environment on hospital admissions from diseases of the circulatory system by using three biometeorological indices in five regions of the Iberian Peninsula. A theoretical index based on a thermophysiological model (Universal Thermal Climate Index [UTCI]) and two experimental biometeorological ones (Net Effective Temperature [NET] and Apparent Temperature [AT]) were estimated in two metropolitan areas of Portugal (Porto and Lisbon) and in three provinces of Spain (Madrid, Barcelona and Valencia). Subsequently, their relationship with hospital admissions, adjusted by NO₂ concentration, time, and day of the week, was analyzed using a Generalized Additive Model. As the estimation method, a semi-parametric quasi-Poisson regression was used. Around 53% of the hospitalizations occurred during the cold periods. The admissions rate followed an upward trend over the 9-year period in both capitals (Madrid and Lisbon) as well as in Barcelona. An inverse and statistically significant relationship was found between thermal comfort and hospital admissions in the five regions (p < 0.001). The highest relative risk (RR) was found after a cumulative 7-day exposure in Lisbon, where there was a 1.4% increase in hospital admissions for each NET and AT degree Celsius, and 1.0% for each UTCI degree Celsius. In conclusion, low air temperatures are a significant risk factor for hospital admissions from diseases of the circulatory system in the Iberian Peninsula, regardless of the index calculated.

The Road Not Taken: Building Physics, and Returning to First Principles in Sustainable Design

The path we are currently following towards ‘sustainable design’ is a result of the accidents of the past 300 years of history. If we look further back, to before the exploitation of fossil fuels, we find a very different approach to building envelopes, and to building use and comfort. This was necessarily very low carbon, and demonstrably effective, but, unfortunately, we have forgotten many of the fundamental principles on which it rested. This paper argues that our current choice of retrofit pathway is leading us away from, rather than towards, a sustainable built environment. Current efforts to reduce carbon and energy based on modern ’layered’ envelopes and misunderstandings of thermal comfort are proving much less effective than predicted. We would further argue that they are too often delivering unintended consequences: contributing to the overuse of carbon and energy, and derailing the development of a sustainable built environment. We draw on research and case studies, as well as on the lessons from history, to show how the problem derives from a neglect of first-principles thinking and fundamental building physics. Equally, though, we show how combining good building physics with a re-evaluation of older approaches to construction and building use delivers some powerful and effective tools for tackling the climate emergency.

Rethinking indoor thermal comfort in the era of rebound and pre-bound effect for the developing world: A systematic review

This paper presents a review on thermal comfort research that is informed by changes in occupant behavior, lifestyle, and income leading to rebound or pre-bound effect. It explores the current state of research in thermal comfort domain through a systematic review to identify the gaps and opportunities specifically focusing on energy-intensive developing countries. This review argues that adaptive thermal comfort is a continuously evolving domain owing to dynamic modifications in occupant behavior occurring from changes in the cost of energy services and preference of comfort (rebound/pre-bound effect). A conceptual framework linking thermal comfort, rebound/pre-bound effect, and occupant behavior is forwarded through the introduction of an exogenous factor related to occupant well-being. The results ascertain that there is a need of localized thermal comfort model with an occupant-centric approach that can help in enhancing comfort and reducing energy consumption.

Effect of ventilation strategies and air purifiers on the children's exposure to airborne particles and gaseous pollutants in school gyms

Indoor school gyms are environments characterized by high concentrations of different airborne particulate and gaseous pollutants. In particular, like other naturally-ventilated school environments, in addition to indoor pollutants children can be exposed to sub-micron particles and gaseous pollutants emitted by outdoor sources and penetrating the building envelope; moreover, high concentrations of super-micron particles can be reached due to the resuspension phenomena related to the physical activity performed therein. The present paper aims to evaluate the effect of different ventilation methods (natural ventilation, manual airing) and the use of air purifiers in reducing the indoor concentrations of different airborne particles and gaseous pollutants in school gyms. To this end, an experimental campaign was performed in two naturally-ventilated school gyms in Barcelona (Spain) of different volumes and different distance to major urban roads. Indoor and outdoor measurements of particle number, black carbon and PM_1-10 concentrations were performed as well as indoor measurements of CO₂ and NO₂ concentrations. The study revealed that the use of air purifiers with windows kept closed (natural ventilation) can lead to a significant reduction in terms of indoor-to-outdoor concentration ratios. In the smaller gym (air changes per hour of the purifiers, ACH, equal to 9.2 h^-1) the I/O ratios were reduced by 93% and 95% in terms of particle number and PM_1-10, respectively; whereas in the larger school gym (ACH = 1.7 h^-1) the corresponding reductions were 70% and 84%. For manual airing scenarios, the effect of the air purifiers on outdoor-generated sub-micron particles is reduced; in particular, for low ACH values (i.e. ACH = 1.7 h^-1), the reduction is quite negligible (6%).

Factors Affecting the Thermal Comfort of Perioperative Personnel in the OR

Thermal comfort is an important component of any work setting and can be difficult to achieve in the complex OR environment. This comparative descriptive study sought to identify factors affecting the thermal comfort of perioperative personnel in the OR (N = 68). Researchers used the American Society of Heating, Refrigerating and Air-Conditioning Engineers Thermal Sensation Scale and researcher-developed surveys to collect data. The mean reported thermal comfort level was -0.44 (standard deviation 1.3), which is within acceptable parameters. Factors affecting thermal comfort were gender, professional role, and wearing additional clothing. Additionally, participants who complained about temperature or ventilation were less likely to report thermal comfort levels in the normal range. Health care facility leaders should consider the comfort needs of perioperative personnel when making purchasing decisions about ventilation systems and surgical clothing; however, they also should consider other factors (eg, surgeon comfort, permeability of protective clothing to blood and other body fluids).

Thermostat wars? The roles of gender and thermal comfort negotiations in household energy use behavior

Although advanced thermostat technologies offer energy efficiency potential, these devices alone do not guarantee savings. Household occupants often deviate from thermostat programs, perhaps due to differing thermal comfort preferences, which are strong drivers of residential energy use and vary across genders. This study aims to develop an initial typology of interpersonal interactions around thermal comfort, explore the role of gender in such interactions, and examine the impacts of interactions on thermostat adjustments. Using n = 1568 diary observations collected from 112 participants, we identify three interaction types: conflicts, compromises, and agreements. Fixed effects analyses find that women are marginally more likely to report engaging in conflicts, whereas men are significantly more likely to report engaging in agreements and compromises, both of which are associated with greater likelihood of adjusting thermostats within a given day. This work represents an early step in investigating the multiply determined nature of household energy decisions.

The Effects of High-Temperature Weather on Human Sleep Quality and Appetite

High-temperature weather appears in high frequency, big strength, and long duration in the summer. It is therefore important to study the effects of high-temperature weather on sleep quality and appetite. Ten healthy college students were selected as subjects. The experiment conditions were divided by the daily maximum temperature into 28 °C, 32 °C, 36 °C, and 38 °C. The objective sleep quality was measured by an intelligent sleep monitoring belt, and the subjective sleep quality was measured by a questionnaire survey. The subjective appetites were assessed by a visual analog scale (VAS), and the objective appetites were assessed by the meal weight and the meal time. For sleep quality, the objective results indicated that the sleep quality at 32 °C was the best, followed by 28 °C, while the sleep quality at 36 °C and 38 °C was the worst. Significant effects were mainly reflected in sleep duration and shallow sleep. The subjective results showed that temperature had significant effects on sleep calmness, difficulty in falling asleep, sleep satisfaction, and sleep adequateness. For appetite, the VAS results indicated that high temperatures mainly led to a reduction of appetite at lunch time. The meal weights of lunch were larger than those of supper except for 28 °C, and the meal time of lunch and supper was longer than that of breakfast. The meal time of lunch was longer than that of supper except for 36 °C. This paper can provide a study method and reference data for the sleep quality and appetite of human in high-temperature weather.