While wearing a mask may reduce the risk of contracting respiratory infectious diseases, it may have some negative side-effects. Few studies have systematically explored whether current indoor comfort temperature standards still apply to the special situation of wearing a mask indoors. To address this issue, we conducted climate chamber experiments. The experimental settings included three temperature conditions (24 degrees C, 26 degrees C and 30 degrees C), and two mask conditions (wearing and not wearing a surgical mask). The relative humidity was maintained at 60 % in all 6 conditions. During the 170-minute mask-wearing period, the cognitive performance, physiological parameters and subjective assessments of 12 males and 12 females were compared in a repeatedmeasures experiment to explore the effects of temperature and mask-wearing. The results show that at a neutral temperature of 26 degrees C (but not at 24 degrees C or 30 degrees C), wearing a surgical mask significantly reduced speed in the multiplication test and accuracy in the Stroop test during some test periods, with increased cardiac variability and end-tidal carbon dioxide concentration suggesting that the mechanism for the effect was that wearing a mask had undesirable respiratory and cardiovascular consequences that caused our subjects to exert less effort. Wearing a mask did not affect the perceived air quality or the overall or local thermal sensation. The present results suggest that a slightly cool or slightly warm environment may have masked the impact of wearing a surgical mask, but more studies are necessary to confirm this observation.

We summarized studies examining the effects on sleep quality of poor bedroom air quality caused by inadequate ventilation. Two questions were addressed: 1) How does inadequate ventilation affect sleep? and 2) What ventilation rates are required to maintain bedroom air quality that does not reduce sleep quality? We identified and analyzed recent research studies that measured both bedroom ventilation and sleep quality. Our findings suggest that currently prescribed minimum ventilation rates for residential environments may provide insufficient ventilation for bedrooms and may thus lead to disturbed sleep. Specifically, the results suggest that absolute carbon dioxide (CO2) levels generated by sleeping occupants should, as a minimum, remain below 1,000 ppm, and preferably below 800 ppm; in this context, CO2 is an indicator of ventilation sufficiency, not a pollutant. To achieve these levels of CO2, bedroom outdoor air supply rates should be at least doubled compared to existing standards. While further research is needed to confirm these conclusions, the results provide strong justification for revising residential building ventilation standards and developing more energy-efficient solutions that will ensure compliance with the recommendations formulated in the present paper.

COVID-19 has made the public aware that wearing masks is a simple yet effective protective measure when facing respiratory infectious diseases. However, despite this late stage of the pandemic, there have been few systematic studies of the physiological and subjective effects of wearing a mask, particularly on how they affect cognitive performance. To address this gap, we conducted an experiment simulating an office environment with three working conditions: no mask, surgical mask, and KN95 mask, 24 subjects and a comfortable ambient temperature of 23 °C; the exposure time to each condition was 160 min (mask was worn for 120 min). We collected data on cognitive performance, physiological parameters, and subjective feelings. The results revealed a significant decrease in the accuracy of a test of grammatical logic as the experiment progressed, regardless of the mask type worn; on average, accuracy was lower when wearing a surgical mask compared with no mask. After 80 min of exposure, the accuracy of a visual choice reaction time test significantly decreased when wearing a surgical mask compared to not wearing a mask, while Stroop accuracy improved slightly but significantly when wearing a KN95 mask. Regardless of mask type, pNN50, ETCO2, and facial skin temperature significantly increased compared to no mask, while wearing a mask reduced the subjects' evaluation of the quality of the thermal environment and the air quality and increased the intensity of some acute health symptoms. In summary, it was shown that wearing masks may impact cognitive performance, physiological responses and well-being.

Humans emit carbon dioxide (CO2) as a product of their metabolism. No measurements of CO2 emission rates (CERs) of elderly sleeping people have yet been reported. This study performed such measurements and examined the possible mechanisms impacting CERs. Sixteen participants (8 males) aged >= 65 years old slept alone for a whole night under each of the four conditions in a 2 x 2 design: air temperatures of 27 degrees C and 30 degrees C and ventilation rates of 5 m3/h per person and 28 m3/h per person (resulting in an average indoor CO2 concentration of about 1200 ppm and 760 ppm, respectively). Physiological responses were recorded during sleep. Indoor parameters including CO2 concentration were continuously measured during and after sleep period. The CERs were calculated using a mass-balance model. The results show that the average CER was 9.0 +/- 1.6 L/h per person. It was ca. 20% higher for males than for females, probably due to higher body mass, body surface area, and longer time awake during sleep. Compared with 27 degrees C, the CER was about 10% higher at 30 degrees C probably due to longer time awake and higher heart rate and skin temperature at this condition. No significant differences in CERs were observed between the two ventilation rates. The CERs measured in the present study for elderly are slightly lower than recently reported for young adults and 10-12 year old children. They all provide information required for estimating ventilation rates in bedrooms assuming that the ventilation is achieved with clean outdoor air.

Sleep is essential for the health of elderly people, but few studies have made connection between their sleep quality and their bedroom environment. This study performed field measurements in Shanghai, China, to investigate the bedroom thermal environment and ventilation and their associations with the sleep quality of elderly subjects in summer. Forty-five elderly subjects participated in this study for six consecutive days. Their bedroom air temperature, relative humidity and CO2 concentration were measured continuously and their sleep quality was objectively measured using a wrist-worn sleep tracker. Wrist skin temperature was measured continuously at night. Each morning after waking up the subjects assessed their sleep quality, recalled their thermal sensation, and recorded their bed covering, sleepwear and cooling/ventilation arrangements during that night. The results show that higher air temperature and CO2 concentration were both negatively correlated with objective sleep quality. Air temperature was the key factor influencing objective sleep quality. When air temperature increased by 1 degrees C, sleep efficiency (SE) decreased by 0.7%, duration of Rapid Eye Movement (REM) sleep decreased by 2.1min, and time awake increased by 2.3min. The sleep quality of elderly subjects was more negatively affected by heat exposure than has been previously reported for younger subjects. As CO2 concentration increased by 100 ppm, the Total Sleep Time (TST) decreased by 11min. The combined effects of air temperature, relative humidity and CO2 concentration were analyzed: TST and duration of REM sleep were reduced at higher air temperature, relative humidity and CO2 concentration.

This chapter sets out a rationale and some detailed recommendations for selecting the most efficient metrics and methods for applied research on how any factor that determines Indoor Environmental Quality (IEQ) – such as Indoor Air Quality (IAQ) – affects building occupants, with the specific purpose of obtaining a scientific basis for the economic and engineering decisions that must be made when constructing and operating buildings. These are decisions that affect a building's first cost, operating cost, energy-efficiency, environmental impact, and sustainability. The expense of meeting the goals in each of these areas must be justified in terms of how IEQ will affect the occupants of the building in terms of their health, comfort, and performance. There may be costs and benefits in each of these areas, and the IEQ effects on them must be quantified if they are to be used in cost-benefit analyses to justify the above expenses. The metrics and measures and the research strategy discussed in this chapter can be used for this applied purpose, to assess the effects of any environmental factor in the indoor environment, including those determining thermal conditions, air quality, acoustic conditions, and lighting.

Ten healthy young adults slept one by one in a specially designed and constructed sleep capsule located in a climate chamber at two temperatures (24 degrees C and 28 degrees C) and two ventilation rates that ensured that the resulting CO2 concentrations were 800 and 1700 ppm. Subjectively rated sleep quality was reduced at 28 degrees C and reduced ventilation, while sleep onset latency was longer under these conditions. Sleep efficiency was lower at 28 degrees C. Subjectively rated fatigue and sleepiness decreased after sleeping under all conditions but less so after sleeping at 28 degrees C. The subjects indicated that their work performance improved after sleeping at 24 degrees C but not when ventilation was reduced and the temperature increased. Both objectively measured and subjectively rated work performance was worse after sleeping in the condition with increased temperature. The subjects felt warmer at 28 degrees C although the thermal environment was still rated as acceptable but the air in the capsule was rated stuffier, the acceptability of the air quality decreased and the rated odour intensity increased at this condition. The wrist skin temperature was always higher at 28 degrees C with reduced ventilation but only during the sleep onset latency period. The subjects felt slightly warm and rated the air stuffier when ventilation was reduced. The present results, albeit from a small exploratory pilot study, show that increased temperature and reduced ventilation both have negative effects on sleep quality, which may have consequences for next-day work performance. These pilot experiment results require validation due to the low number of subjects.

Three conditions were established to investigate the effects of ventilation and related ventilation noise on sleep quality: No mechanical ventilation/low noise (A); Mechanical ventilation /low noise (B); Mechanical ventilation/high noise (C). The interventions were achieved by idling a mechanical ventilation system or operating it in two different modes. Nine young people and nine older people were all exposed to each of the three conditions for a whole night's sleep, but data from only 15 subjects were analyzed as three young subjects apparently slept with open windows in condition A. Sleep quality was measured objectively with polysomnography (PSG), which monitored signals of electroencephalogram (EEG), bilateral electrooculogram (EOG), and chin electromyogram (EMG) continuously during the sleeping period. Saliva samples were collected before sleep at night and after waking in the morning, and the concentrations of cortisol and lysozyme in them were determined. Without mechanical ventilation, the indoor CO2 level averaged about 1400 ppm during the night. Operating the mechanical ventilation decreased the indoor CO2 to below 1000 ppm, which improved objectively measured sleep quality: wake time after sleep onset (WASO) decreased on average by 15 min (p < 0.05) and sleep efficiency (SE) increased on average by about 4% (p < 0.05). Increased ventilation noise level (50.8dB(A) vs. 34.7dB(A); 54.9dB(C) vs. 48dB(C)) did not significantly change SE or WASO but did change the duration of sleep stages: It decreased the duration of deep sleep by 11min (p < 0.05) and REM sleep by 17 min (p < 0.01) and increased the duration of light sleep by 17 min (p < 0.05). The ventilation noise significantly increased the concentration of lysozyme in the elderly (p < 0.05) although no significant effects on cortisol could be shown. These results confirm that a low ventilation rate has negative effects on sleep quality and that ventilation noise at or above 50dB(A) may disrupt sleep.

This study managed to create thermal comfort conditions at three temperatures (24°C-T24, 26°C-T26, and 28°C-T28) by adjusting clothing and air velocity. Thirty-six subjects (18 males and 18 females) were exposed to each of the three conditions for 4.5 h in a design balanced for order of presentation of conditions. During each exposure, they rated the physical environment, their comfort, the intensity of acute subclinical health symptoms, and their mental load, and they performed a number of cognitive tasks. Their physiological reactions were monitored. The subjects rated T24 to be comfortably cool, T26 to be comfortably neutral, and T28 to be comfortably warm. Their self-estimated performance did not differ between conditions but 12 of 14 objective metrics of cognitive performance decreased significantly at the elevated temperatures: compared with T24, their average cognitive performance decreased by 10% at T26 and by 6% at T28. At the elevated temperatures, their parasympathetic nervous system activity (as indicated by PNN50) and their arterial blood oxygen saturation level (SpO2) were both lower, which would be expected to result in reduced cognitive performance. The subjects also rated their acute subclinical health symptoms as more intense and their workload as higher at the elevated temperatures. These results suggest that where cognitive performance is the priority, it is wise to ensure a comfortably cool environment. The present study also supports the use of fans or natural ventilation to reduce the need for mechanical cooling.

This study investigated whether adjusting clothing to remain in neutral thermal comfort at moderately elevated temperature is capable of avoiding negative effects on perceived acute subclinical health symptoms, comfort and cognitive performance. Two temperatures were examined: 23°C and 27°C. Twelve subjects were able to remain thermally comfortable at both temperatures by adjusting their clothing. They rated the physical environment, their comfort, the intensity of acute subclinical health symptoms and their mental load and they performed a number of cognitive tasks. Their physiological reactions were monitored. Their performance of several tasks was significantly worse at 27°C and they reported increased mental load at this temperature. Skin temperature and humidity and respiration rate were higher while blood oxygen saturation (SpO2) and pNN50 were lower at this temperature, the latter indicating increased stress. It is inferred that the observed physiological responses were mainly responsible for the negative effects on performance, as the subjects did not indicate any increased intensity of acute subclinical health symptoms although perceived air quality was worse at the higher temperature. The present results suggest that moderately elevated temperatures should be avoided even if thermal comfort can be achieved, as it may lead to reduced performance.

Sensory input from the skin appears to be of crucial importance in the regulation of sleep but there has been limited research on human skin temperature during sleep. The present study was undertaken to validate calculation of the mean skin temperature (MST) of sleeping subjects from measurements at only three locations: forehead, chest, and foot, by means of an analysis of skin temperature data obtained from four human experiments that investigated the effects of thermal environment on the sleep quality and thermal comfort of a total of 64 sleeping subjects. The results show that skin temperatures were more evenly distributed across the body surface of sleeping subjects than they are when subjects are awake. The skin temperature of the forehead was highly correlated with thermal sensation in long-term measurements. MST values calculated using the three-point method were found to predict thermal sensation while sleeping better than those calculated using the normally accepted Hardy and Dubois's seven-point method. The validity, convenience and reliability of this approach, which also causes less sleep disturbance, makes it a suitable choice for obtaining estimates of mean skin temperature in sleep studies.

Is sleep becoming so much scarcer than ever before because people do not realize the importance of sleep for health and well-being? All over the world, digital communications now mean that contact with work continues after hours and during weekends and that "friends" are no longer just the people we meet regularly, but the many more we contact regularly. These new contacts compete strongly for our time with online entertainment and news, our leisure activities and our immediate families, and there are still only 24 hours in each day.

A two-week-long intervention study was performed in two classrooms in an elementary school in Costa Rica. Split-cooling air-conditioning (AC) units were installed in both classrooms. During the first week, the air temperature was reduced in one classroom while in the other (placebo) classroom the fans were operated but no cooling was provided. During the second week, the conditions were exchanged to create a 2 × 2 crossover design in which each pupil was their own control. A total of 37 children performed tasks similar to school work and completed questionnaires reporting their thermal sensation and perceptions. Operating the AC units reduced classroom temperature by about 5 K, from about 30 to 25°C. Thermal sensations changed from hot to neutral and slightly cold, and the percentage of children rating the thermal conditions as acceptable increased significantly. Neutral temperature was estimated to be about 27°C. The 11-year-old children performed the language and logical-thinking tasks significantly better in terms of speed at the lower temperature, while the less able pupils performed better on all tasks at the lower temperature. There were no significant effects on accuracy. These results confirm published findings from moderate climates and extend their validity to the tropics. They indicate that acclimatization can increase the optimal temperature for learning.

A field-intervention study was carried out in 106 households in Sweden. Without informing the householders, a retrofitted heat pump controller was twice disabled for 1 week at a time over a 4-week period during the heating season, using a single-blind cross-over design with two pseudorandomly selected groups of householders, each experiencing different conditions at any given time. Thermal comfort was assessed by observing the total number of times that householders made adjustments to their set point temperature under each condition. A within-household, repeated-measures analysis was performed to determine whether this indicator was positively or negatively affected when the secondary controller was disabled so the heat pump system operated as designed. While over 80% of households showed no effect, among those that did respond to the imposed changes, a Wilcoxon matched-pairs signed-ranks test indicates that disabling the retrofitted controller had a negative effect on thermal comfort (P < 0.05 for a 2-tail test), in that it resulted in significantly more thermostat adjustments. A concurrent increase in the variance of indoor temperature about the household mean was significant (P < 0.001) but small: The range within which indoor temperatures were maintained for 95% of the time (2.5 K) was increased by only 0.3 K (16%), indicating the sensitivity of the approach.

Energy conservation in buildings as a way to reduce the emission of greenhouse gases is forcing an urgent re-examination of how closely thermal and air quality conditions should be controlled in buildings. Allowing conditions to drift outside the optimum range would conserve very large amounts of energy and would in most cases have only marginal effects on health or subjective comfort. The question that then arises is whether occupant performance would be negatively affected and if so, by how much. This information is required for cost-benefit analyses. The answers in this paper are based on laboratory and field experiments that have been carried out since the massive increase in energy costs that took place in the 1970s. Although only a few of the mechanisms by which indoor environmental effects occur have been identified, it is already clear that any economies achieved by energy conservation will be greatly exceeded by the costs incurred due to decreased performance. Reducing emissions by allowing indoor environmental conditions to deteriorate would thus be so expensive that it would justify greatly increased investment in more efficient use of energy in buildings in which conditions are not allowed to deteriorate. Labour costs in buildings exceed energy costs by two orders of magnitude, and as even the thermal and air quality conditions that the majority of building occupants currently accept can be shown to reduce performance by 5–10% for adults and by 15–30% for children, we cannot afford to allow them to deteriorate still further.

The effects of bedroom air quality on sleep and next-day performance were examined in two field-intervention experiments in single-occupancy student dormitory rooms. The occupants, half of them women, could adjust an electric heater to maintain thermal comfort but they experienced two bedroom ventilation conditions, each maintained for 1 week, in balanced order. In the initial pilot experiment (N = 14), bedroom ventilation was changed by opening a window (the resulting average CO2 level was 2585 or 660 ppm). In the second experiment (N = 16), an inaudible fan in the air intake vent was either disabled or operated whenever CO2 levels exceeded 900 ppm (the resulting average CO2 level was 2395 or 835 ppm). Bedroom air temperatures varied over a wide range but did not differ between ventilation conditions. Sleep was assessed from movement data recorded on wristwatch-type actigraphs and subjects reported their perceptions and their well-being each morning using online questionnaires. Two tests of next-day mental performance were applied. Objectively measured sleep quality and the perceived freshness of bedroom air improved significantly when the CO2 level was lower, as did next-day reported sleepiness and ability to concentrate and the subjects' performance of a test of logical thinking.

Indoor AirVolume 24, Issue 5 p. 552-553 Letter to the Editor The Adaptive Thermal Comfort model may not always predict thermal effects on performance D. P. Wyon, D. P. Wyon International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark (DTU), Lyngby, DenmarkSearch for more papers by this authorP. Wargocki, P. Wargocki [email protected] International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark (DTU), Lyngby, DenmarkSearch for more papers by this author D. P. Wyon, D. P. Wyon International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark (DTU), Lyngby, DenmarkSearch for more papers by this authorP. Wargocki, P. Wargocki [email protected] International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark (DTU), Lyngby, DenmarkSearch for more papers by this author First published: 12 September 2014 https://doi.org/10.1111/ina.12098Citations: 5Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume24, Issue5October 2014Pages 552-553 RelatedInformation