Gender differences in thermal comfort and use of thermostats in everyday thermal environments

Differences in thermal comfort between male and female subjects are generally considered to be small. In this study gender differences in thermal comfort and use of thermostats were examined by a quantitative interview survey with a total of 3094 respondents, and by controlled experiments. The studies were carried out in Finland and considered everyday thermal environments: homes, offices and a university. The results show significant gender differences in thermal comfort, temperature preference, and use of thermostats. Females are less satisfied with room temperatures than males, prefer higher room temperatures than males, and feel both uncomfortably cold and uncomfortably hot more often than males. Although females are more critical of their thermal environments, males use thermostats in households more often than females.     

How people use thermostats in homes: A review

Residential thermostats control a substantial portion of both fuel and electrical energy—9% of the total energy consumption in the U.S. Consumers install programmable thermostats to save energy, yet numerous recent studies found that homes with programmable thermostats can use more energy than those controlled manually depending on how—or if—they are used. At the same time, thermostats are undergoing a dramatic increase in capability and features, including control of ventilation, responding to electricity price signals, and interacting with a home area network. These issues warrant a review of the current state of thermostats, evaluating their effectiveness in providing thermal comfort and energy savings, and identifying areas for further improvement or research.     

Thermal comfort in transitional spaces—basic concepts: literature review and trial measurement

Current thermal comfort research extensively documents various aspects of the human thermal response to stable environmental conditions. Reviews of recent research on outdoor comfort, however, reveals a lack of information on response to conditions in transitional spaces—those areas that are influenced by outdoor climate, yet are architecturally bounded by a building. In this work, we focused on transitional space as a space in between outdoor and indoor. Transitional spaces were organized into three categories depending on their proximity to interior spaces. Pilot measurements of physical variables were taken in six places. Transitional spaces’ physical environments varied by the space type and architectural characteristics. The typical behaviors observed were walking, standing, and sitting —different and varied compared to the sedentary behavior in offices or homes. The most efficient architectural shape of transitional spaces is related to the corresponding regional climatic condition. It was verified that PMV cannot be used for transitional space thermal comfort predictions because of its unstable and dynamic physical and MET value.     

An algorithm to represent occupant use of windows and fans including situation-specific motivations and constraints

A theoretical model of the interaction between a building and its occupants is developed based on field survey data; the role of the model in building performance simulation is illustrated. If free to do so, people adjust their clothing or available building controls (windows, blinds, doors, fans, and thermostats) with the aim of achieving or restoring comfort and reducing discomfort. Initially responses to thermal conditions are considered. Trigger temperatures are established where responses to warm or cold thermal discomfort may occur. These trigger-temperatures depend on (among other things) clothing (which may depend on season and social conditions) and air movement (e.g., fan setting). Trigger-temperatures differ from person to person and from time to time. If several controls are available people will use those that are most user-friendly, effective and free from undesirable consequences, and this is represented in the model by a constraint assigned to each control option. The concept of constraints is then expanded to capture non-thermal stimuli for control use (e.g., fresh-air). Using datasets from surveys in Europe and Pakistan, estimates are made of the parameters used in the model: the comfort temperature in relation to the prevailing outdoor temperature, the extent of inter-personal variation of trigger temperature, the effect of a fan on the comfort temperature, and the values of constraints that affect the use of windows and fans in the surveyed buildings. The incorporation of the new model, including constraints, into building simulation code is illustrated. Some limitations or unknowns in the current model are identified and possible approaches for future research to fill these gaps suggested. The application of the model in building performance analysis and building design is discussed.     

感知控制对湿热地区户外庭园空间热舒适性的影响——以华侨大学“世外·花缘”生活实验室为例

户外热舒适对城市景观空间的使用具有显著影响。目前对户外热舒适的研究较少考虑感知控制(Perceived Control)的影响作用。通过在选定实验区域内对志愿者进行问卷调查,分析感知控制对庭园空间热舒适的影响。结果表明：1)感知控制对湿热地区庭园空间的夏季中性温度具有一定影响,但对秋、冬季中性温度影响微弱;2)感知控制受限会导致热感觉的敏感程度增强,热舒适范围变窄;3)在中性温度范围附近,感知控制对热舒适感的影响十分微弱,而在热感觉为“冷”“凉”“暖”“热”的热环境中,感知控制对不适感具有一定缓解作用;4)感知控制在一定程度上扩大了人们对庭园热环境的可接受范围,当感知控制受限时,人们对热环境的接受度会有所下降。     

Numerical investigation of local thermal discomfort in offices with displacement ventilation

Local thermal discomfort in offices with displacement ventilation is investigated using computational fluid dynamics. The standard κ-ϵ turbulence model is used for the prediction of indoor air flow patterns, temperature and moisture distributions, taking account of heat transfer by conduction, convection and radiation. The thermal comfort level and draught risk are predicted by incorporating Fanger's comfort equations in the airflow model. It has been found that for sedentary occupants with summer clothing common complaints of discomfort in offices ventilated with displacement systems result more often from an unsatisfactory thermal sensation level than from draught alone. It is shown that thermal discomfort in the displacement-ventilated offices can be avoided by optimizing the supply air velocity and temperature. It is also shown that optimal supply air conditions of a displacement system depend on the distance between the occupant and air diffuser.     

User problems with individual temperature control in offices

Individual thermal control is important for handling personal differences in thermal preference. Several studies have shown that comfort, health and productivity in offices can be improved by individual thermal control. Local controls for temperature are commonly available in modern office buildings. However, office occupants are often still dissatisfied with the thermal environment and their control options. In this study we used contextual techniques to gain an understanding of the user problems with individual temperature control. A total of 27 office occupants in 13 Finnish buildings were interviewed in their offices. They were asked to show and tell us how they use the controls. The results show that the temperature controls were often not used in thermal discomfort. A diversity of problems with individual temperature control was identified and are listed with proposed solutions. The main reason for the many of the problems is that systems are planned and constructed without a realistic view of their users, and end users are presumed to have knowledge they don’t have. The users should be studied and more effort should be put into user interface development.     

Dwelling performance and adaptive summer comfort in low-income Australian households

Increasing reliance on air-conditioning to improve summertime comfort in dwellings results in higher energy bills, peak electricity demand and environmental issues. In pursuit of social equity, society needs to develop ways of improving cooling that are less reliant on air-conditioning. Designing homes to emphasize adaptive thermal comfort can reduce this reliance, particularly when combined with improved dwelling thermal performance. A multi-method evaluation of 10 low-income dwellings in the state of Victoria in Australia is presented, including low-energy and ‘standard-performance’ houses. The combination of performance monitoring and householder interviews reveals new insights for achieving summertime comfort. The low-energy houses without air-conditioning were both measured and perceived as more comfortable than the ‘standard-performance’ houses with air-conditioning. The low-energy households achieved improved personal thermal comfort through a combination of improved fabric performance augmented with adaptive comfort activities (e.g., opening/closing windows). This outcome reduces reliance on air-conditioning, reduces living costs and energy consumption, and improves environmental outcomes. There is a need to integrate lessons from adaptive thermal comfort theory and strategies into minimum building performance requirements and standards, as well as wider design strategies. It is evident that adaptive comfort has a role to play in a transition to a low-carbon housing future.     

Forty years of Fanger’s model of thermal comfort: comfort for all?

The predicted mean vote (PMV) model of thermal comfort, created by Fanger in the late 1960s, is used worldwide to assess thermal comfort. Fanger based his model on college-aged students for use in invariant environmental conditions in air-conditioned buildings in moderate thermal climate zones. Environmental engineering practice calls for a predictive method that is applicable to all types of people in any kind of building in every climate zone. In this publication, existing support and criticism, as well as modifications to the PMV model are discussed in light of the requirements by environmental engineering practice in the 21st century in order to move from a predicted mean vote to comfort for all. Improved prediction of thermal comfort can be achieved through improving the validity of the PMV model, better specification of the model's input parameters, and accounting for outdoor thermal conditions and special groups. The application range of the PMV model can be enlarged, for instance, by using the model to assess the effects of the thermal environment on productivity and behavior, and interactions with other indoor environmental parameters, and the use of information and communication technologies. Even with such modifications to thermal comfort evaluation, thermal comfort for all can only be achieved when occupants have effective control over their own thermal environment. PRACTICAL IMPLICATIONS: The paper treats the assessment of thermal comfort using the PMV model of Fanger, and deals with the strengths and limitations of this model. Readers are made familiar to some opportunities for use in the 21st-century information society.     

Combating overheating: mixed-mode conditioning for workplace comfort

ABSTRACT

Using post-occupancy evaluations of seven mixed-mode buildings – three in Australia and four in India – this paper demonstrates that effective mixed-mode conditioning (instead of year-round air-conditioning) can deliver comfortable workspaces. Occupant feedback reinforces strong associations between overheating, thermal comfort, overall comfort and perceived productivity. However, differing levels of thermal acceptability within and between the Australian and Indian contexts are evident. Occupants in the Indian buildings were found to tolerate a wider range of temperatures when compared with Western contexts where lower temperature limits entrench an energy demand through a greater reliance on air-conditioning. The outcomes from the study suggest that the perception of overheating and consequent risk to building performance can be intensified when occupants perceive limited adaptive opportunity or problems are not rectified quickly, whereas perceived control is less important where building systems are user responsive. Occupants in three of the study buildings also perceived higher-than-anticipated comfort which could be attributable to well-liked attributes, such as break-out spaces, daylight and fresh air included in these buildings. The findings challenge designers and clients to develop user-responsive climate interactive workplaces that capitalize on spatial and mixed-mode environmental control to tackle the question of overheating.     

Thermal comfort of people in the hot and humid area of China—impacts of season,climate, and thermal history

We conducted a climate chamber study on the thermal comfort of people in the hot and humid area of China. Sixty subjects from naturally ventilated buildings and buildings with split air conditioners participated in the study, and identical experiments were conducted in a climate chamber in both summer and winter. Psychological and physiological responses were observed over a wide range of conditions, and the impacts of season, climate, and thermal history on human thermal comfort were analyzed. Seasonal and climatic heat acclimatization was confirmed, but they were found to have no significant impacts on human thermal sensation and comfort. The outdoor thermal history was much less important than the indoor thermal history in regard to human thermal sensation, and the indoor thermal history in all seasons of a year played a key role in shaping the subjects' sensations in a wide range of thermal conditions. A warmer indoor thermal history in warm seasons produced a higher neutral temperature, a lower thermal sensitivity, and lower thermal sensations in warm conditions. The comfort and acceptable conditions were identified for people in the hot and humid area of China.     

Thermal zoning and interzonal airflow in the design and simulation of solar houses: a sensitivity analysis

Many assumptions must be made about thermal zoning and interzonal airflow for modelling the performance of buildings. This is particularly important for solar homes, which are subjected to high levels of periodic solar heat gains in certain zones. The way in which these passive solar heat gains are distributed to other zones of a building has a significant effect on predicted energy performance, thermal comfort and optimal design selection. This article presents a comprehensive sensitivity analysis that quantifies the effect of thermal zoning and interzonal airflow on building performance, optimal south-facing glazing area, and thermal comfort. The effect of controlled shades to control unwanted solar gains is also explored. Results show that passive solar buildings, in particular, can benefit from increased air circulation with a forced air system because it allows solar gains to be redistributed and thus reduces direct gain zone overheating and total energy consumption.     

Draught,Radiant Temperature Asymmetry and Air Temperature – a Comparison between Measured and Estimated Thermal Parameters

Thermal comfort measurements were taken in 17 enterprises at 129 work sites in shops, stores and offices. The measurements included air temperature, air velocity, relative humidity and radiant temperature asymmetry according to ISO 7726 and ISO 7730 standards. The workers also answered a questionnaire dealing with thermal comfort. Predicted mean vote (PMV) and the percentages of workers complaining of draught (“percentage dissatisfied”, PD) were determined and compared with the workers' assessments of thermal conditions. The estimations of air temperature were always too low, and the estimated PMV indicated that the thermal environment was too warm. The calculated PMVs were usually lower than the estimated ones. Most of the workers complained of draught, even though, according to the PD index, fewer than 17% of the workers should have felt discomfort due to draught. The radiant temperature asymmetry was always small and did not explain complaints of draught on the basis of the reference value. Judged by the present reference values, and the measurement of the thermal environment, the workers overestimated the sensation of thermal discomfort.     

Thermal comfort in care homes: vulnerability,responsibility and ‘thermal care’

Care homes are a distinctive setting for the management of thermal comfort due to the expectations involving the provision of both a home environment and caring service. Based on six UK case studies, the care home setting is investigated for how owners, managers and staff understand thermal needs and how their management of thermal comfort is shaped. The core function of good quality care is understood as closely related to the provision of thermal comfort. The association between ‘old and cold' and the obligations that follow for the provision of care are deeply entrenched in activities: such as the provision of hot drinks, use of blankets and the non-stop operation of heating systems. The responsibility for the provision of ‘thermal care' for residents is challenging and complicated by the diversity of people living (and working) together, their occupation of communal spaces, and the interactions between the means of providing thermal comfort and physical safety. The wider implications are identified for the uptake of sustainable technology, patterns of thermal-related vulnerability and, most significantly, for how the ethics, agency and relationality of thermal care provision are to be understood. Future research needs and directions are considered.     

A field investigation of the thermal environment and adaptive thermal behavior in bedrooms in different climate regions in China

Sleep thermal environments substantially impact sleep quality. To study the sleep thermal environment and thermal comfort in China, this study carried out on-site monitoring of thermal environmental parameters in peoples’ homes, including 166 households in five climate zones, for one year. A questionnaire survey on sleep thermal comfort and adaptive behavior was also conducted. The results showed that the indoor temperature for sleep in northern China was more than 4°C higher than that in southern China in winter, while the indoor temperatures for sleep were similar in summer. Furthermore, 70% of people were satisfied with their sleep thermal environment. Due to the use of air conditioning and window opening in various areas in summer, people were satisfied with their sleep thermal environments. Due to the lack of central heating in the southern region in winter, people feel cold and their sleep thermal environment needs further improvement. The bedding insulation in summer and winter in northern China was 1.83clo and 2.67clo, respectively, and in southern China was 2.21clo and 3.17clo, respectively. Both northern China and southern China used air conditioning only in summer. People in southern China opened their windows all year, while those in northern China opened their windows during the summer and transitional periods.     

Ventilation and health in non-industrial indoor environments: report from a European multidisciplinary scientific consensus meeting (EUROVEN)

Scientific literature on the effects of ventilation on health, comfort, and productivity in non-industrial indoor environments (offices, schools, homes, etc.) has been reviewed by a multidisciplinary group of European scientists, called EUROVEN, with expertise in medicine, epidemiology, toxicology, and engineering. The group reviewed 105 papers published in peer-reviewed scientific journals and judged 30 as conclusive, providing sufficient information on ventilation, health effects, data processing, and reporting, 14 as providing relevant background information on the issue, 43 as relevant but non-informative or inconclusive, and 18 as irrelevant for the issue discussed. Based on the data in papers judged conclusive, the group agreed that ventilation is strongly associated with comfort (perceived air quality) and health [Sick Building Syndrome (SBS) symptoms, inflammation, infections, asthma, allergy, short-term sick leave], and that an association between ventilation and productivity (performance of office work) is indicated. The group also concluded that increasing outdoor air supply rates in non-industrial environments improves perceived air quality; that outdoor air supply rates below 25 l/s per person increase the risk of SBS symptoms, increase short-term sick leave, and decrease productivity among occupants of office buildings; and that ventilation rates above 0.5 air changes per hour (h-1) in homes reduce infestation of house dust mites in Nordic countries. The group concluded additionally that the literature indicates that in buildings with air-conditioning systems there may be an increased risk of SBS symptoms compared with naturally or mechanically ventilated buildings, and that improper maintenance, design, and functioning of air-conditioning systems contributes to increased prevalence of SBS symptoms.     

Associations of perceived indoor environmental quality with stress in the workplace

Indoor environmental quality (IEQ) is a general indicator of the quality of conditions inside a building. We investigated associations of perceived IEQ including air quality, thermal comfort, noise, and light quality with stress at work and the extent to which workplace location modifies these associations. We recruited 464 full-time workers from four companies in Singapore. Data on socio-demographic characteristics, lifestyle/health-related factors, and workplace factors were collected through self-administered questionnaires. Perceived IEQ satisfaction scores of all four factors were collected using the validated OFFICAIR questionnaire. We fitted a logistic regression model to assess associations between each perceived IEQ score and stress at work, adjusting for potential confounders. The odds ratio for stress at work associated with a 1-unit increase in perceived air quality score was 0.88 (0.82-0.94), 0.89 (0.82-0.97) for thermal comfort, 0.93 (0.87-0.98) for noise, and 0.88 (0.82-0.94) for light quality. Significant associations were found in office and control rooms for all four perceived IEQ, except for thermal comfort in office rooms. Higher satisfaction levels of perceived air quality, thermal comfort, noise, and lighting, were significantly associated with a reduction in stress at work. Our findings could potentially provide a useful tool for environmental health impact assessment for buildings.     

Adaptive thermal comfort in the residential buildings of north east India—An effect of difference in elevation

Thermal comfort standards are required not only to ensure good indoor climatic condition, but also to optimize the energy used in a building for heating or cooling purposes. Generally, Fanger’s Predicted Mean Vote–Predicted Percentage Dissatisfied (PMV–PPD) model is used by designers and architects to estimate the comfort condition and hence the setpoint temperature inside a building. However, the recent field survey based studies on adaptive thermal comfort suggests that the above used PMV model frequently either underestimates or overestimates the thermal sensation due to the non-inclusion of the adaptive opportunities that a subject may have in maintaining comfortable condition. This leads to often an estimation of higher or lower setpoint temperature than that actually required for maintaining comfort, thereby consuming higher energy. The aim of the research is to study the effect of difference in elevation which is a major factor for temperature difference in hilly terrain, on the thermal comfort of residents. We conducted a field survey in 6 residential buildings at two different elevations in the Darjeeling Himalayan Region of north east India. A total of 1017 questionnaires regarding the indoor occupant thermal comfort were collected from 46 subjects during the monthly survey held in the year 2015. Variations in clothing insulation and other thermal comfort parameters were seen both with difference in elevation and with outdoor environmental conditions.     

Comfort of workers in office buildings: The European HOPE project

Previous studies have shown that building, social and personal factors can influence one’s perceived health and comfort. The aim of the underlying study was to get a better understanding of the relationships between these factors and perceived comfort. Self-administered questionnaires from 5732 respondents in 59 office buildings and building-specific data from the European Health Optimisation Protocol for Energy-efficient buildings (HOPE) study were used. Principal Component Analysis (PCA), reliability analyses, and linear regression analysis were performed. The outcome showed that perceived comfort is strongly influenced by several personal, social and building factors and that their relationships are complex. Results showed that perceived comfort is much more than the average of perceived indoor air quality, noise, lighting and thermal comfort responses. Perceived comfort is a phenomenon that deserves more research.     

Thermal pleasure in built environments: physiology of alliesthesia

International standards that define thermal comfort in uniform environments are based on the steady-state heat balance equation that posits ‘neutrality’ as the optimal occupant comfort state for which environments are designed. But thermal perception is more than an outcome of a deterministic, steady-state heat balance. Thermal alliesthesia is a conceptual framework to understand the hedonics of a much larger spectrum of thermal environments than the more thoroughly researched concept of thermal neutrality. At its simplest, thermal alliesthesia states that the hedonic qualities of the thermal environment are determined as much by the general thermal state of the subject as by the environment itself. A peripheral thermal stimulus that offsets or counters a thermoregulatory load-error will be pleasantly perceived and vice versa, a stimulus that exacerbates thermoregulatory load-error will feel unpleasant. The present paper elaborates the thermophysiological hypothesis of alliesthesia with a particular focus on set-point control and the origins of thermoregulatory load-error signals, and then discusses them within the broader context of thermal pleasure. Alliesthesia provides an overarching framework within which diverse and previously disconnected findings of laboratory experiments, field studies and even comfort standards spanning the last 40 years of thermal comfort research can be more coherently understood.