Patient thermal comfort requirement for hospital environments in Taiwan

This study examines the comfort criteria of ASHRAE Standard 55-2004 for their applicability in hospital environments. Through an extensive field survey conducted in a university hospital in Taiwan, 927 sets of data have been collected. Above half of the measured samples failed to meet the specifications of Standard 55 comfort zone due to improper humidity control. Acceptability votes by patients exceeded the Standard's 80% criterion, regardless of whether the physical conditions were in or out of the comfort zone. Thermal neutrality, preference and comfort range are compared with other studies conducted in office environments and Standard 55 criteria. Results of chi-square tests revealed that patients’ physical strength significantly effected their thermal requirements. The net effect of health yields a marked difference in thermal neutrality and preference, and also in the comfortable temperature range.     

A study on the thermal comfort in sleeping environments in the subtropics—Developing a thermal comfort model for sleeping environments

In the subtropics, air conditioning serves to maintain an appropriate indoor thermal environment not only in workplaces during daytime, but also at night for sleeping in bedrooms in residences or guestrooms in hotels. However, current practices in air conditioning, as well as the thermal comfort theories on which these practices are based, are primarily concerned with situations in which people are awake in workplaces at daytime. Therefore, these may not be directly applicable to air conditioning for sleeping environments. This paper, reports on a theoretical study on a thermal comfort model in sleeping environments. A comfort equation applicable to sleeping thermal environments was derived by introducing appropriate modifications to Fanger's comfort model. Comfort charts which were established by solving the comfort equation, and can be used for determining thermally neutral environmental conditions under a given bedding system have been developed. A related paper reports on an experimental study on measuring the total thermal insulation values of a wide range of bedding systems commonly used in the subtropics, which are an essential input to the comfort equation developed and reported in this paper.     

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.     

A model of human physiology and comfort for assessing complex thermal environments

The Berkeley Comfort Model is based on the Stolwijk model of human thermal regulation but includes several significant improvements. Our new model allows an unlimited body segments (compared to six in the Stolwijk model). Each segment is modeled as four body layers (core, muscle, fat, and skin tissues) and a clothing layer. Physiological mechanisms such as vasodilation, vasoconstriction, sweating, and metabolic heat production are explicitly considered. Convection, conduction (such as to a car seat or other surface in contact with any part of the body) and radiation between the body and the environment are treated independently. The model is capable of predicting human physiological response to transient, non-uniform thermal environments. This paper describes the physiological algorithms as well as the implementation of the model.     

Relationship between thermal sensation and comfort in non-uniform and dynamic environments

The relationship between thermal sensation and thermal comfort was studied experimentally under uniform and non-uniform, steady and dynamic conditions separately. Thirty subjects participated in all the experiment and reported their thermal sensation and thermal comfort simultaneously. Thermal sensation and comfort are found to be correlated closely under steady and uniform conditions and the comfort zone of thermal sensation vote in warm side is (0, 1.25). Under steady and non-uniform conditions thermal sensation change with space is found to be an important factor determining thermal comfort. Combining the effects of overall thermal sensation and thermal sensation change with space, a thermal comfort model for steady conditions is proposed. Under dynamic conditions, thermal sensation change with time affects thermal comfort significantly.     

A field study of occupant thermal comfort and thermal environments with radiant slab cooling

This paper presents the findings of a field study of occupant thermal comfort and thermal environments with a radiant slab cooling system. The study combined field measurements and questionnaires based on the ASHRAE RP-921 project protocol. A total of 116 sets of data from 82 participants were collected in summer and winter. The results reveal that occupant whole-body thermal sensations with radiant cooling were consistent with the PMV model. The main advantage of radiant cooling for thermal comfort was found to be reduced local thermal discomfort with reduced vertical air temperature difference as well as reduced draft rate. The survey results revealed that 14–22% of participants in the study reported local cold discomfort in the arm–hand and the leg–foot regions. The results indicated that there may be lower limits on air speeds acceptable to occupants. Statistical analysis indicated that occupant thermal votes were free of significant correlation with personal, contextual and psychological factors. Suggestions to improve the questionnaire and the field survey process are offered.     

均匀和不均匀热环境下热感觉、热可接受度和热舒适的关系

对30名受试者采用问卷调查的方式,研究了均匀热环境和不均匀热环境下人体全身热感觉、热可接受度和热舒适的关系。结果显示,在均匀热环境下,全身热感觉、热可接受度和热舒适具有较强的线性相关关系,可接受范围涵盖了(0,1.5)的热感觉投票和"舒适"与"稍有不适"标度范围内的热舒适投票;在不均匀热环境下,全身热可接受度与热舒适密切相关,而全身热感觉与热可接受度和热舒适出现分离,热感觉不均匀度是其原因。综合考虑全身热感觉和热感觉不均匀度的影响,提出了综合评价模型。经验证,该模型适用于全身热状态为中性偏热的均匀和不均匀热环境。     

Integrating 4D thermal information with BIM for building envelope thermal performance analysis and thermal comfort evaluation in naturally ventilated environments

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Comfort in urban spaces: defining the boundaries of outdoor thermal comfort for the tropical urban environments

With rapid urbanisation, often without climate responsive guidelines, cities in the Tropics are progressively falling short of sustaining outdoor life. While at the building level such inadvertent climatic modifications have lead to a remarkable demand on the urban energy resources. The rationale for developing a thermally desirable outdoor ambience in such a context has implications that go beyond the requisites of urban design and well into the design of buildings. In order to re-establish and sustain life outdoors it is important that we try to make urban spaces comfortable as far as the ambient climate permits. In order to ascertain conditions of comfort for outdoor spaces we need to define comfort for outdoors. This paper presents findings on outdoor comfort based on field investigations conducted in Dhaka, a city in the wet-Tropics. Findings from a survey conducted on a large number of randomly selected people from urban spaces are presented. The findings include factors affecting comfort outdoors for Dhaka and a comfort regime based on environmental parameters for urban outdoors is presented. Interestingly, comfortable ambient climate leads to comfortable indoor environment particularly with regard to free running buildings. With regard to mechanically controlled indoor environments a comfortable outdoor produces lesser strain on energy environment relationship. By defining conditions of comfort for outdoor environments an important step towards achieving sustainability of our urban environments can be made.     

Objective criteria for thermal comfort

For thermal comfort an objective definition is given, based on physiological results. The significance of skin temperature in this context is the basis for a measurement device which simulates the human skin physically. Results of measurements using the artificial skin including psychophysical investigations and draught measurements are discussed as well as the applicability of the objective comfort criteria to current HVAC problem areas. Finally the significance of the equivalent temperature for future standardization is emphasized.     

Turbulence correction for thermal comfort calculation

Thermal comfort in ventilated spaces depends mainly on air temperature, air speed and turbulence intensity. Mean air speed is commonly measured with omnidirectional hot sphere sensors, whereas directionally sensitive measurement instruments and CFD-simulations normally give the mean velocity vector. The magnitude of the mean velocity vector in turbulent room air flows can be much lower than the mean air speed due to different time averaging processes. This paper studies the difference both experimentally and theoretically as a function of turbulence intensity. A correction method was developed for calculating estimates for omnidirectional mean air speed and turbulence intensity from directional air velocity data. The method can be applied to the calculation of draught risk and thermal comfort from CFD-simulation results.     

Evolving opportunities for providing thermal comfort

The building industry needs a fundamental paradigm shift in its notion of comfort, to find low-energy ways of creating more thermally dynamic and non-uniform environments that bring inhabitants pleasure. Strategies for providing enriched thermal environments must be conjoined with reducing energy; these are inseparable for any building striving for high performance. The objective of current comfort standards is to have no more than 20% of occupants dissatisfied, yet buildings are not reaching even that scant goal. A significant energy cost is incurred by the current practice of controlling buildings within a narrow range of temperatures (often over-cooling in the summer). If building designers and operators can find efficient ways to allow building temperatures to float over a wider range, while affording occupants individual control of comfort, the potential for energy savings is enormous. Five new ways of thinking, or paradigm shifts, are presented for designing or operating buildings to provide enhanced thermal experiences. They are supported by examples of research conducted by the Center for the Built Environment, and include shifts from centralized to personal control, from still to breezy air movement, from thermal neutrality to delight, from active to passive design, and from system disengagement to improved feedback loops.     

Adaptive thermal comfort and sustainable thermal standards for buildings

The origin and development of the adaptive approach to thermal comfort is explained. A number of recent developments in the application of the theory are considered and the origin of the differences between adaptive thermal comfort and the ‘rational’ indices is explored. The application of the adaptive approach to thermal comfort standards is considered and recommendations made as to the best comfort temperature, the range of comfortable environments and the maximum rate of change of indoor temperature. The application of criteria of sustainability to thermal standards for buildings is also considered.     

Studying thermal comfort in context

This commentary considers the recent Building Research & Information special issue titled ‘Comfort in a Lower Carbon Society’ and what it suggests about how to conduct contextual studies of thermal comfort. Firstly, consideration is given to the places within which comfort is examined and how research might beneficially trespass beyond the borders of the building to explore how lifestyles combine various places with a range of social expectations and techniques for managing personal temperature. Secondly, the suggestion is that whilst it could be worthwhile to examine various lifestyles, contextually sensitive researchers must select the groups they study carefully and acknowledge the limitations associated with this choice. Thirdly, it considers which practical methods are most appropriate for this line of research and how existing approaches could be supplemented by techniques currently uncommon in this field. The overall argument is that qualitative approaches with groups of current users could identify the most sensitive ways of steering societies towards more sustainable thermal futures.

Ce commentaire analyse le récent numéro spécial de Building Research & Information intitulé « Le confort dans une société sobre en carbone » et ce qu'il suggère sur la façon de mener des études contextuelles du confort thermique. L'auteur s'intéresse tout d'abord aux lieux où le confort est examiné et comment la recherche pourrait avantageusement dépasser les frontières du bâtiment pour voir comment les styles de vie combinent divers lieux avec une gamme d'attentes sociales et de techniques pour gérer la température personnelle. Puis, alors qu'il pourrait être intéressant d'examiner divers styles de vie, il suggère que les chercheurs sensibles au contexte sélectionnent des groupes qu'ils étudient avec soin et reconnaissent les limites associées à ce choix. Enfin, il considère les méthodes pratiques qui seraient les plus appropriées pour cette ligne de recherche et comment les approches existantes pourraient être complétées par des techniques qui sont actuellement rares dans ce domaine. L'argument général est que les approches qualitatives avec des groupes d'utilisateurs actuels pourraient jouer un rôle utile dans l'identification des solutions les plus judicieuses pour diriger les sociétés vers un avenir thermique plus durable.

Mots clés: adaptation, agence, confort, société sobre en carbone, satisfaction de l'occupant, méthodes qualitatives, consommation durable     

Thermal comfort assessment in semi-outdoor environments: Application to comfort study in stadia

The present study addresses thermal comfort assessment of outdoor and semi-outdoor environments. Two stadium case studies are used to demonstrate the potentiality of the approach that combines wind tunnel data and the calculation of human heat balance due to particular climatic environments. The thermal index PET (physiological equivalent temperature) is used to evaluate the thermal comfort in such complex environments. The specificities of stadium semi-outdoor spaces are summarised and the necessary assumptions made to apply the computation procedure are described. The approach includes assumptions on the thermo-physical phenomena as well as geometric computations. This work benefited from the development of an interactive design tool of built environments (outdoor urban surroundings): EVE (enriched virtual environments). It is a virtual reality platform developed at CSTB to help designers, architects and urban planners to evaluate the various options in competition regarding acoustic, visual, thermal and wind comfort of pedestrian in a particular urban environment.     

Capabilities and limitations of thermal models for use in thermal comfort standards

Thermal models of the human body and its interactions with the surrounding thermal environment are often proposed, and to some extent are used, as the basis for thermal comfort standards. These models range from simple, one-dimensional, steady-state simulations to complex, transient, finite element codes with thousands of nodes. The models are potentially very useful in that they provide a straightforward means to incorporate the numerous physical variables that affect comfort. Some models can be applied to complex situations which would be difficult, if not impossible, to reflect in simple charts or equations. Whether simple or complex, all of these models have limitations for use in standards. These limitations include the accuracy of the physical simulation and the accuracy of the inputs to the model. Perhaps, the biggest limitation is the accuracy with which comfort perceptions can be related to the physiological variables simulated in the thermal models.     

Using electroencephalogram to continuously discriminate feelings of personal thermal comfort between uncomfortably hot and comfortable environments

Thermal comfort is an important factor for the design of buildings. Although it has been well recognized that many physiological parameters are linked to the state of thermal comfort or discomfort of humans, how to use physiological signal to judge the state of thermal comfort has not been well studied. In this paper, the feasibility of continuously determining feelings of personal thermal comfort was discussed by using electroencephalogram (EEG) signals in private space. In the study, 22 subjects were exposed to thermally comfortable and uncomfortably hot environments, and their EEG signals were recorded. Spectral power features of the EEG signals were extracted, and an ensemble learning method using linear discriminant analysis or support vector machine as a sub-classifier was used to build the discriminant model. The results show that an average discriminate accuracy of 87.9% can be obtained within a detection window of 60 seconds. This study indicates that it is feasible to distinguish whether a person feels comfortable or too hot in their private space by multi-channel EEG signals without interruption and suggests possibility for further applications in neuroergonomics.     

偏热环境下空调非等温可感送风对人体热舒适影响的实验研究

通过实验研究在2个工况下,低温稳态气流、低温仿自然风动态气流以及等温仿自然风动态气流方式下,受试者热感觉、热舒适和热环境满意度投票情况。实验结果表明,在室温为28~30℃、相对湿度为40%~45%的热环境下,平均送风速度为0.5~0.7m/s、送风温度为28℃的气流能够使受试者达到舒适水平。建议当室温为28℃时,使用风扇提供平均风速为0.5m/s的仿自然风动态气流进行人体降温;当室温为30℃时,使用空调提供平均风速为0.5m/s、送风温度为28℃的仿自然风动态气流进行人体降温。     

The theoretical basis of comfort in the ‘selective’ control of environments

This paper draws together the main results and conclusions of a programme of research, into the theory and practice of environmental control in buildings, which has been conducted over a period of ten years. A study of the theoretical basis of the ‘environmental system’ is shown to have informed a series of field investigations into the way in which the users of buildings respond to the physical environment and, consequently, exercise control over it. A fundamental distinction is drawn between the ‘exclusive’ and ‘selective’ modes of environmental control, and the results of the field studies are used to develop some general principles of the nature of a ‘selective’ mode building. These are illustrated through the development of a ‘generic’ cross-section for the teaching wing of a primary school building.