Thermal comfort and psychological adaptation as a guide for designing urban spaces

Energy and Buildings 35 (2003) 95 101 Thermal comfort and psychological adaptation as a guide for designing urban spaces Marialena Nikolopoulou a,*, Koen Steemers b,1 a Centre for Renewable Energy Sources (CRES), 19th km Marathonos Avenue, Pikermi 19009, Greece b The Martin Centre for Architectural and Urban Studies, Department of Architecture, University of Cambridge, Cambridge CB2 2EB, UK Abstract Investigating thermal comfort conditions in outdoor urban spaces, has thrown some light on the complexity of the issues involved, demonstrating that a quantitative approach is insufficient in describing comfort conditions outdoors. It revealed that although microclimatic parameters strongly influence thermal sensation, they cannot fully account for the wide variation between objective and subjective comfort evaluation, whereas, psychological adaptation seems to becoming increasingly important. This paper concentrates on the issue of psychological adaptation: naturalness, expectations, experience (short-/long-term), time of exposure, perceived control and environmental stimulation, and presents an attempt to try and evaluate the relative impact of each of these parameters. Understanding the interrelationship between the different parameters of psychological adaptation would be of interest in order to compare their relative significance, and to assess their design role, that is whether design considerations would influence these parameters, or vice versa, whether they could influence design decisions. An awareness of these issues would be valuable to architects, planners and urban designers, not by the way of limiting possible solutions, rather by enriching the design possibilities. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Outdoor comfort; Adaptation; Urban spaces; Design considerations 1. Introduction Understanding and evaluating thermal comfort conditions in urban spaces is necessary, as this can have major implications for the development of cities. Investigating thermal comfort in the urban context through 1431 interviews at four different sites in the city-centre of Cambridge at different times of the year has thrown some light on the complexity of the issues involved, and has demonstrated that a quantitative approach is insufficient in describing comfort conditions outdoors [1]. Evaluation of comfort was done comparing the recorded environmental parameters air and globe temperature, wind speed and humidity with the subjective human behaviour and responses people gave at the interviews. Before engaging in the discussion on the thermal comfort conditions of outdoor spaces, however, a differentiation has to be drawn between routes and resting places. In the study presented here, we are concerned with resting areas, since people choose to sit somewhere, whereas, a particular route * Corresponding author. Tel.: þ30-10-6603300; fax: þ30-10-6603301. E-mail address: mnikol@cres.gr (M. Nikolopoulou). 1 Tel.: þ44-1223-331700; fax: þ44-1223-331701. is less likely to be chosen, in order to avoid discomfort. Nevertheless, such discomfort will not cause them serious distress, since the time of exposure to the specific environmental conditions is short. On the other hand, with resting places the situation is different, as poor comfort conditions may distress people and lead them to avoid using these areas. The study revealed that microclimatic parameters indeed strongly influence thermal sensations, but such an approach only accounted for around 50% of the variation between objective and subjective comfort evaluation. The rest could not be measured by physical parameters, but psychological adaptation seemed to become increasingly important, accommodating wide fluctuations in the physical environment, so that thermal discomfort is avoided. This paper concentrates on the issues comprising psychological adaptation: naturalness, expectations, experience (short- and long-term), time of exposure, perceived control and environmental stimulation, as it has not been possible so far to quantify these effects, the relative weight of each parameter is not known. An attempt is presented here to try and evaluate the relative impact of each of these parameters. Understanding the interrelationship between the different parameters of psychological adaptation would be of interest 0378-7788/03/$ see front matter # 2003 Elsevier Science B.V. All rights reserved. PII: S 0378-7788(02)00084-1

96 M. Nikolopoulou, K. Steemers / Energy and Buildings 35 (2003) 95 101 in order to compare their relative significance, and to assess their design role, that is whether design considerations would influence these parameters, or vice versa, whether they could influence design decisions. Some of these parameters are inherent to the qualities of a space, whereas, others are more personal, variables people bring in the space. The complexity of these relationships is also variable, as none of them follows a simple cause and effect situation. In some of these, satisfaction with the thermal environment of the space will depend as much on the space itself, as it will on personal variables people bring to the area with them, and the former will affect the latter, whereas, the latter will affect the perception of the former. However, despite the complexity of the above interrelations, it is possible to consider without being deterministic design issues which would have some impact on the above parameters, as described further below. This would in turn increase the range that psychological adaptation could take place, therefore, widening the range of environmental conditions considered as comfortable. An awareness of these issues would be valuable to architects, planners and urban designers, not by the way of limiting possible solutions, rather by enriching the design possibilities. 2. Thermal sensation The interviews demonstrated that thermal, and by implication comfort conditions, affect people s use of outdoor spaces. Responses to the microclimate might have been unconscious but have resulted in a different use of urban space in different climatic conditions [1]. Examining the number of people using the different spaces at various time intervals, revealed that warm conditions and the presence of the sunlight are the important factors in the use of the space, as shown in Fig. 1, where the average number of people sitting in the space increases as globe temperature increases. Most importantly, however, comparison of objective with subjective data revealed that there was a great discrepancy Fig. 1. Variation of the number of people outdoors, in relation to globe temperature. Fig. 2. Comparison between actual percentage and predicted percentage of dissatisfied. between the two, regarding thermal comfort conditions outdoors. The predicted percentage of dissatisfied (PPD), based on the theoretical calculation of the predicted mean vote (PMV) for each interviewee [2], (getting a mean value from the individual calculated PPDs), was compared with the corresponding actual percentage of dissatisfied (APD) (Fig. 2). The PPD varies from 56% in spring to 91% in winter, whereas, the yearly average is 66%. That implies 944 of the 1431 people sitting outside should be dissatisfied with their thermal environment. In fact, the APD is always around 10%, a figure that is regarded as acceptable, found even in controlled indoor environments. In agreement with most field studies carried out in buildings, the current results suggest that adaptation takes place. Furthermore, the wide variation of environmental parameters outdoors, in contrast to indoor conditions, accentuate this discrepancy. 3. Adaptation The term adaptation can be broadly defined as the gradual decrease of the organism s response to repeated exposure to a stimulus, involving all the actions that make them better suited to survive in such an environment. In the context of thermal comfort, this may involve all the processes which people go through to improve the fit between the environment and their requirements. Within such a framework, adaptive opportunity can be separated into three different categories: physical, physiological and psychological [3]. A brief description of these categories is necessary, in order to obtain a clear understanding of the different issues involved, and to be in a position to get into more depth on the subject of psychological adaptation.

M. Nikolopoulou, K. Steemers / Energy and Buildings 35 (2003) 95 101 97 3.1. Physical adaptation Physical adaptation involves all the changes a person makes, in order to adjust oneself to the environment, or alter the environment to his needs. We can, therefore, identify two different kinds of adaptation, reactive and interactive [3]. In reactive adaptation, the only changes occurring are personal, such as altering one s clothing levels, posture and position, or even metabolic heat with the consumption of hot or cool drinks. In interactive adaptation, however, people make changes to the environment in order to improve their comfort conditions, such as opening a window, turning a thermostat, opening a parasol, etc. 3.2. Physiological adaptation Physiological adaptation implies changes in the physiological responses resulting from repeated exposure to a stimulus, leading to a gradual decreased strain from such exposure. In the context of the thermal environment, this is called physiological acclimatization. Such a mechanism becomes crucial in extreme environments, but in the context of the current research, it is not of central importance. 3.3. Evidence for psychological adaptation Different people perceive the environment in a different way, and the human response to a physical stimulus is not in direct relationship to its magnitude, but depends on the information that people have for a particular situation. Psychological factors are, therefore, influencing the thermal perception of a space and the changes occurring in it, as described below. 3.3.1. Naturalness This is a term employed by Griffiths et al. [4], describing an environment free from artificiality, whereby there seems to be increasing evidence that people can tolerate wide changes of the physical environment, provided they are produced naturally. The best example that this is an important parameter in people s perception of outdoor spaces is perhaps highlighted in Fig. 2, where the respective PPD and APD profiles are very different. In such places, where all the climatic changes occur naturally, wide changes of the physical environment are tolerated. 3.3.2. Expectations Expectations that is what the environment should be like, rather than what it actually is greatly influence people s perceptions, such as in naturally ventilated buildings, where people expect variations in temperatures, both temporally and spatially, whereas, in air-conditioned spaces they expect a much more stable thermal environment. In outdoor spaces this relates to the frequent reply people gave throughout the year it s OK for this time of year, for this time of year I would prefer it warmer, or it s winter it s meant to be cold. In the few instances, where thermal conditions deviated from what people were experiencing the previous days, this caused differences in people s sensation votes or even complaints, as their expectations had changed. This was in agreement to the findings of a Norwegian study [5,6], where minimum comfort temperature in autumn was 11 8C, whereas, in spring it was 9 8C. Expectations varied as a result of the much cooler temperatures preceding the spring. 3.3.3. Experience Experience directly affects people s expectations and can be differentiated in short- and long-term. Short-term experience is related to the memory and seems to be responsible for the changes in people s expectations from one day to the following. This also explains why thermal neutrality for outdoor conditions was found to vary from 7.5 8C in winter to 27 8C in summer, lying close to the mean air temperature [1], as physical adaptation only partly justify this range of temperatures. Long-term experience is related to the schemata people have constructed in their minds, determining a choice of action under different circumstances. Therefore, changes in clothing, consumption of cool drinks to alter the metabolic heat, moving from sun to shade, etc., all represent wellestablished choices of action on the issue of how to cope with the variable thermal environment. As Wohlwill argues, adaptation levels are established as functions of past exposure [7]. Open spaces, whether in the form of squares or parks, are familiar places for everyone, and so are our associations with them. 3.3.4. Time of exposure Exposure to discomfort is not viewed negatively if the individual anticipates that it is short-lived, such as getting out of a warm car to enter a building in winter, and no significant dissatisfaction is caused. This is a critical factor for external spaces, which apart from movement, they are mainly used for recreational activities, and people modify the time they spend outside, according to their needs. The time people spent in the different sites varied enormously, but the thermal perception of the environment was an important parameter influencing people s decision on how long to spend in the area. Two different aspects seemed to influence this decision: the subjects current thermal sensation and the subjects short-term thermal history. Generally, unless exposure to discomfort is threatening for the living organism explaining sensitivity to the cold rather than heat tolerance to the thermal environment is great. 3.3.5. Perceived control It is now widely acknowledged that people who have a high degree of control over a source of discomfort, tolerate wide variations, are less annoyed by it, and the negative emotional responses are greatly reduced. People who

98 M. Nikolopoulou, K. Steemers / Energy and Buildings 35 (2003) 95 101 mentioned choosing their sitting positions so that the choice of both the sun and the shade was open to them, further reinforces this point. It is not important whether they actually moved position eventually, the critical issue was that the choice was available. Similarly, this choice of sitting in the sun or the shade also affected the amount of time spent outdoors. This was longest in the sites that had a variety of spaces available with 50 min average in the summer offering both exposure to the sun and the shade, and shortest in the area where no shading was offered 16 min average in the summer. Another form of perceived control over the environment became apparent when investigating the reasons people gave for being in the spaces, particularly in relation to their comfort state. It became apparent that the amount of people feeling uncomfortable and dissatisfied with the thermal environment was higher when the only reason for being there was to meet someone, rather than other reasons. In particular, 23% of the population using the space as a meeting place, waiting for another person to arrive, reported dissatisfaction with the thermal environment (Fig. 3). This amount of dissatisfaction decreases by half to 12%, for the population that have gone to the space for other reasons. Put in a different way ([8], p. 378): Lack of action at any particular point in time does not necessarily imply the absence of intention to act in the future. In fact, adapting to or tolerating a stress or may be easier if one intends to engage in active coping in the future. Therefore, people who are in the space for various reasons are aware that it was their own choice to expose themselves to these conditions, and when they wish can leave, becoming more tolerant to the thermal environment. However, people who were there to meet someone did not have the option of leaving when they wished to do so. The termination of their exposure to the thermal conditions was dependent on external factors, in this case the arrival of the other person, which was causing distress, making them less tolerant to the environment. This issue of free choice becomes of prime importance in outdoor spaces, where actual control over the microclimate is minimal, perceived control having the biggest weighting. 3.3.6. Environmental stimulation Comfortable conditions have been regarded as those where occupants feel neither warm nor cold, where ambient conditions are neutral. However, it is increasingly believed that a variable, rather than fixed, environment is preferred, whereas, a static environment becomes intolerable. Environmental stimulation is an issue of primary importance in external spaces, where the environment presents few thermal constraints, this being an important asset of such areas and one of the reasons that people use these spaces. Environmental stimulation is probably the main reason for the majority of people to sit outdoors. This was the most popular reason people gave in spring, when they were asked why they were in the area, as well as being a popular response to what they liked about the area. Further evidence for this is the fact that the majority of interviewees actual thermal sensation votes (ASVs) were recorded in the þ1 warm category and followed by 1 cool, but not 0 which corresponded to neutrality (Fig. 4). Furthermore, the fact that the majority of people were found outdoors in higher temperatures when the majority of ASVs was þ1, suggests that people enjoy feeling warm. Further support on this point, was obtained examining the average time people spent outdoors, which also corresponded to ASV ¼þ1, and not neutrality. People enjoyed feeling warm and when such conditions arise, they stay the longest, taking advantage of the situation. This would probably be reversed in a warm climate when enjoyment would correspond to conditions described as cool. The need for variability and stimulation was also found to be especially desirable for people working in a building and coming out for their lunch-break. This was demonstrated by examining people s short-term thermal history before coming outdoors, i.e. where they were before, in a building or outdoors. People coming directly from buildings spent the longest time in warm and hot conditions. Fig. 3. Percentage satisfaction: (i) theoretical predictions according to the Fanger PPD model [2]; (ii) people in the area by their own choice and; (iii) those waiting for another person to arrive. Fig. 4. Frequency distribution for interviewees actual thermal sensation votes (range between 2 and þ2).

M. Nikolopoulou, K. Steemers / Energy and Buildings 35 (2003) 95 101 99 The most plausible justification seems to be that they see the external environment with the fresh air, the sun and the wind as invigorating stimulation for the senses, wishing to spend some time there, before returning to the more monotonous workplace. On the other hand, people having spent enough time outdoors before arriving in the area meant that sensory and thermal equilibrium had been reached. This also suggests that heat storage, a term which is not included in the theoretical PMV model [2], may also be a significant parameter in the evaluation of thermal comfort. Another interesting point arose by examining the number of people sitting in the sun and the shade, in spring and summer, in relation to their short-term thermal history. It was noticed that there is a tendency for people who come out of a building to sit in the sun rather than shade, even at high air temperatures. The need to charge-up the body with the sun was greater than the short-lived and non-threatening physiological strain on the body. On the contrary, the majority of people found sitting in the shade had come from outside. Therefore, if the site itself is very interesting offering different kinds of stimulation, people will have higher tolerances to the extreme conditions, provided they are not threatening, than they would under average circumstances. 3.4. Evaluation of psychological adaptation The effect of physical adaptation can be evaluated numerically. An individual may adjust his temperature range by 6 K [9], or reduce his net metabolic heat by 10% with the reduction of cold drinks [10]. Furthermore, this information can be the input in the physiological model to view explicitly the effect of such measures on the theoretical PMV. With psychological adaptation, however, it has not been possible to quantify effects, and the relative weight of each parameter is not known. An attempt is presented below to try and evaluate the relative impact of the different parameters involved in thermal comfort. 4. Influence of psychological adaptation Understanding the interrelationship between the different parameters of psychological adaptation would be of interest in order to compare their relative significance, and to assess their design role, that is whether design considerations would influence these parameters or vice versa, whether they could influence design decisions. It is not possible to create a speculative network of relationships between the various parameters. Fig. 5 depicts such a network of the different parameters affecting psychological adaptation with lines of influence between them, indicating whether one parameter affects another. Some parameters have a two-way relationship, such as between perceived control and expectations where one affects the Fig. 5. Lines of influence between the different parameters of psychological adaptation. other. These lines are not weight related and there is no magnitude associated with the strength of relationship; they only denote that a relationship exists. They have been developed from common sense, as well as the insights that this research has provided in general. These speculative relationships are summarised in Table 1, where the degree to which the various parameters are influencing and are being influenced by other variables of the same group is presented. It is interesting to notice that the naturalness is judged here to influence other variables, but is not influenced by any parameters of the group. It seems that such a variable is inherent to the space, and is not affected by more personal variables such as perceived control. Furthermore, expectations, environmental stimulation and time of exposure can be seen to be affected by every variable in the group. A more simplified way of presenting this is graphically (Fig. 6), indicating the degree one variable influences and is being influenced by another. The three variables that are influenced by all other parameters of psychological adaptation are presented in one group, to denote the interrelations between them, external connections provided where required. Clearly, this implies that the relationships between Table 1 Speculative interaction of different parameters of psychological adaptation Parameter Influencing parameter Perceived control 3 3 Expectations 3 5 Environmental stimulation 3 5 Experience 4 2 Time of exposure 3 5 Naturalness 4 0 Being influenced by parameter

100 M. Nikolopoulou, K. Steemers / Energy and Buildings 35 (2003) 95 101 Fig. 6. Network demonstrating interrelationships between the different parameters of psychological adaptation. those variables are complex, as it is not a simple cause and effect situation. Satisfaction with the thermal environment of the space will depend as much on the space itself, as it will on personal variables people bring to the area with them, and the former will affect the latter, whereas, the latter will affect the perception of the former. 5. Design consideration Despite the complexity of the above interrelations, it is possible to consider without being deterministic design issues, which would have some impact on the above parameters. This would, in turn, increase the range psychological adaptation that could take place, therefore, widening the range of environmental conditions considered as comfortable. An awareness of these issues would be valuable to architects, planners and urban designers, not by way of limiting possible solutions, rather by enriching the design possibilities. The first parameter considered, influencing without being influenced by other parameters, is the naturalness, which is part of the character of a place. This can be significantly increased, by greening an area, adding vegetation or views of landscape, particularly within the dense urban context, which would accentuate the distinct character of the different areas. This positive evaluation of areas with natural instead of built characteristics has also been verified by other studies [11], where the presence of some trees repeatedly neutralised the negative evaluation of empty space. Past experience is not so much site-related, as much as it is a variable people bring to the space, but some action can be taken to affect it, particularly the short-term experience. This would be more relevant to the design of the urban fabric or the urban block as opposed to a single site. Since, people s thermal sensation is influenced by their immediate shortterm thermal experience, by providing more spatial variety in the city, a rich variety of different environments can be experienced, between indoors and outdoors, affecting their thermal sensation. Perceived control can be affected by providing increased opportunities for physical adaptation to take place. Reactive adaptation, such as clothing and metabolic heat, depends on the individual and is not site-related. Spatial variation, however, is a parameter that can be catered for, providing a variety of sub-spaces within the same area. This would translate into allowing for access to the sun as well as the shade, exposure to breezes as well as protection from the wind, with normally different areas preferred in different seasons. Similarly, transition spaces, such as arcades provide useful spatial variation in areas, which have to cope with harsh winters. Interactive adaptation is infrequent in outdoor spaces [3]. However, movable elements allowing for it, such as parasols or awnings, provide spatial variation with protection from the sun and the rain, and are normally appreciated by users of the space. These are the main parameters that can be influenced from the design point of view, all affecting the remaining time of the exposure, environmental stimulation and expectations. Time of exposure is a personal variable, but may be influenced by people s thermal evaluation of the area, positively for extending their stay in the area, or negatively reducing it. It is, therefore, indirectly affected by the three primary parameters naturalness, experience and perceived control as well as the other two in the same group. The main difference between the different groups is that in the former, design considerations can improve existing conditions either at the stage where an area is being developed, or later by design interventions. A variety of such examples in the former case is consideration of the density of urban textures, orientation of open spaces, width of streets, height of buildings, etc., all affecting solar exposure and shading, as well as wind deflection and wind acceleration through the streets and squares. Creating pleasant or harsh urban spaces can be determined early on, at the design stage. When the urban texture is existent alterations are still possible at the scale of the urban block, in order to improve the microclimate. Microclimatic control is feasible, provided it is acknowledged that the public domain is not to be ignored. Vegetation, used for shading and wind breaks, movable canvas awnings, canopies made of various materials such as reeds, bamboo, or vines provide effective shading and present main architectural features of the street. Furthermore, proprietors of commercial activities are normally the first to realise the potential of such cool oases in a hot environment. The individuals also determine the degree of environmental stimulation desired. However, protection from negative aspects and exposure to positive aspects of the climate can increase such desire. Such microclimatic planning would also increase the use of outdoor spaces during the intermediate seasons. In fact, in Norway, it was found that the outdoor season could be extended by up to 6 weeks

M. Nikolopoulou, K. Steemers / Energy and Buildings 35 (2003) 95 101 101 during the more critical seasons of spring and autumn by appropriate microclimatic planning. This meant providing protection from the wind, orientation to maximise solar exposure, avoiding overshadowing, employing heat absorbing and heat reflecting materials, etc. [6]. Finally, regarding expectations, this is also linked to the design of open spaces but only indirectly, by affecting the degree of perceived control. 6. Conclusions This work has thrown some light on the complexity of issues involved in thermal comfort in outdoor urban spaces, particularly in areas identified as resting places, as opposed to routes. A quantitative approach to the physical parameters has demonstrated that microclimatic parameters, indeed, strongly influence thermal sensations. However, such an approach only accounted for around 50% of the variation of the interviewees ASVs. The rest could not be measured by physical parameters, but psychological adaptation seemed to become increasingly important. Although it was demonstrated that psychological adaptation is very important for the thermal evaluation of outdoor spaces, and there is strong influence between the different parameters, we are unable to develop these speculations in more depth, or point to more deterministic relationships at this stage. We are not yet able to quantify the influence of perceived control on people s expectations and vice versa, nor the influence of environmental stimulation on perceived control, etc. Quantifying the speculative interrelationships presented in Fig. 5 would extend our understanding of the wider notion of thermal comfort. The relevance of such an understanding would not be restricted to open spaces; the indoor built environment would also benefit from such an approach. With respect to the urban context, it is inadequate to design open spaces with regard to thermal comfort, solely on the basis of a physical model. The physical environment is important in outdoor thermal comfort, but psychological adaptation is also an important factor. Although these are largely personal parameters, appropriate microclimatic planning and careful design of urban spaces can provide protection from negative aspects and exposure to positive aspects of the climate, therefore, increasing the use of outdoor space throughout the year. Different seasons require different approaches, but a variety of spaces providing different environments would maximise both physical and psychological adaptation. The physical environment and psychological adaptation is argued to be complementary rather than contradictory, and consideration of this duality could increase the use of the city s open spaces, strengthening social interaction between citizens by allowing opportunities for such interaction to take place. Acknowledgements This work originated from the EU (DG XII) funded project Project ZED: Towards Zero Emission Urban Developments (APAS-RENA CT94-0016) coordinated by Koen Steemers at the Martin Centre, and was co-funded by the Royal Institute of British Architects (RIBA). The authors are currently involved in a new EU-funded research project (5th Framework Programme, City of Tomorrow and Cultural Heritage from the Programme Energy Environment and Sustainable Development) on outdoor comfort which involves the surveying, monitoring and modelling not only thermal as well as visual and acoustic comfort conditions, in cities across Europe. The project, entitled RUROS: Rediscovering the Urban Realm and Outdoor Spaces, is being coordinated by Marialena Nikolopoulou at CRES. References [1] M. Nikolopoulou, N. Baker, K. Steemers, Thermal comfort in outdoor urban spaces: the human parameter, Solar Energy, vol. 70, No. 3, 2001. [2] ISO 7730: Moderate thermal environments determination of the PMV and PPD indices and specification of the conditions for thermal comfort, International Standards Organization, Geneva, 1994. [3] M. Nikolopoulou, N. Baker, K. Steemers, Thermal comfort in urban spaces: different forms of adaptation, in: Proceedings of the REBUILD 1999 on Shaping Our Cities for the 21st Century, Barcelona, 1999. [4] I.D. Griffiths, J.W. Huber, A.P. Baillie, Integrating the environment, in: Steemers, Palz (Eds.), Proceedings of the 1987 European Conference on Architecture, Kluwer Academic Publishers, The Netherlands, 1987. [5] L. Zrudlo, The design of climate-adapted arctic settlements, in: J. Mänty, N. Pressman (Eds.), Cities Designed for Winter, Building Book Ltd., Helsinki, 1988. [6] B. Culjat, R. Erskine, Climate-responsive social space: a Scandinavian perspective, in: J. Mänty, N. Pressman (Eds.), Cities Designed for Winter, Building Book Ltd., Helsinki, 1988. [7] J.F. Wohlwill, Human adaptation to levels of environmental stimulation, Human Ecology 2(2) (1998). [8] J.M. Campbel, Ambient stressors, Environment and Behavior 15(3) (1983). [9] D.A. McIntyre, Indoor Climate, Applied Science Publishers, London, 1980. [10] N. Baker, M. Standeven, Thermal comfort for free-running buildings, Energy and Buildings 23 (1996) 175 182. [11] S. Hesselgren, On Architectures: An Architectural Theory Based on Psychological Research, Chartwell Bratt, UK, 1987.