Application of adaptive thermal comfort methods for Iranian schoolchildren

ABSTRACT

Recent studies in primary schools highlight a need to develop the adaptive comfort model for schoolchildren in classrooms. This study investigates the application of the principal methods underlying the adaptive comfort theory for children relating thermal comfort indoors to the prevailing mean outdoor temperature. Children’s sensitivity to indoor temperature change are examined using data from a field study conducted in Iranian schools. This sensitivity is used to estimate the comfort temperatures in classroom situations with a minimum level of adaptation. Different metrics for the outdoor climate are employed to understand an expression of the climate which best predicts children’s comfort temperature. A sensitivity analysis is performed to derive the relation between indoor comfort and the climate that gives rise to the strongest correlation coefficient. Although the basic adaptive comfort relationships are applicable for children, the exponential method to calculate the prevailing mean with lower decay values leads to higher correlation with children’s comfort temperature. The slope of children’s comfort equation in relation to outdoor temperature is shown to be shallower than those of adults. Results indicate that children are more sensitive to temperature change within a single school day than across the overall survey period of several days.     

Adaptive thermal comfort in Australian school classrooms

This survey of thermal comfort in classrooms aimed to define empirically the preferred temperatures, neutral temperatures and acceptable temperature ranges for Australian school children, and to compare them with findings from adult populations. The survey was conducted in a mixture of air-conditioned, evaporative-cooled and naturally ventilated classrooms in nine schools located in three distinct subtropical climate zones during the summer of 2013. A total of 2850 questionnaires were collected from both primary (grade) and secondary (high) schools. An indoor operative temperature of about 22.5°C was found to be the students’ neutral and preferred temperature, which is generally cooler than expected for adults under the same thermal environmental conditions. Despite the lower-than-expected neutrality, the school children demonstrated considerable adaptability to indoor temperature variations, with one thermal sensation unit equating to approximately 4°C operative temperature. Working on the industry-accepted assumption that an acceptable range of indoor operative temperatures corresponds to group mean thermal sensations of ?0.85 through to +0.85, the present analysis indicates an acceptable summertime range for Australian students from 19.5 to 26.6°C. The analyses also revealed between-school differences in thermal sensitivity, with students in locations exposed to wider weather variations showing greater thermal adaptability than those in more equable weather districts.     

Climatic variations in comfortable temperatures: the Pakistan projects

Two thermal comfort surveys in Pakistan are described. One was longitudinal conducted in summer and winter, the other was transverse with monthly surveys over a whole year. The surveys were conducted in five cities each representing a particular climatic region. The use of building controls and clothing is analysed. There is close agreement between the findings of the two surveys despite differences in methodology. The surveys show that there is a definite relationship between indoor comfort and outdoor conditions in line with an adaptive approach to thermal comfort. The current International Standard does not accurately reflect these. Because of the large variations in indoor temperature in many Pakistani buildings, the surveys also indicate the limits of people's ability to adapt to indoor temperatures.     

Revisiting thermal comfort models in Iranian classrooms during the warm season

The validity of existing thermal comfort models is examined for upper primary school children in classroom settings. This is of importance to enhance productivity in the learning environment and to improve the control of artificial heating and cooling, including the potential for energy savings. To examine the thermal perceptions of children aged 10–12 years in non-air-conditioned classrooms, three sets of field experiments were conducted in boys’ and girls’ primary schools in Shiraz, Iran. These were undertaken during regular class sessions covering cool and warm conditions of the school year, polling responses from 1605 students. This paper illustrates the overall methods and reports the results of the warm season field survey (N?=?811). This investigation suggests that predicted mean vote-predicted percentage of dissatisfied (PMV/PPD) underestimates children's actual thermal sensation and percentage dissatisfied in the investigated classrooms. The analysis shows that sampled children may be slightly less sensitive to indoor temperature change than adults. The upper acceptable temperature derived from children's responses corresponding to mean thermal sensations of +0.85 is 26.5°C, which is about 1°C lower than the ASHRAE upper 80% acceptability limit. This implies that sampled children feel comfortable at lower temperatures than predicted by the ASHRAE Adaptive model during the warm season.     

上海地区适应性热舒适研究

为研究上海地区人体热感觉和适应性热舒适现状,通过环境参数测量和问卷调查结合的方式来分析和探讨室内外气候条件、服装热阻、热感觉等关系。本文主要涉及自然通风建筑内人体热感觉和热中性温度随季节变化的关系。结果表明:在适应性热舒适研究中,人体中性温度与室外环境温度具有较强的相关性,得到的上海地区适应性热舒适模型可为适合我国自身特点的热舒适研究提供依据。     

Thermal perception,adaptation and attendance in a public square in hot and humid regions

Highly relevant to an individual's thermal perception, the thermal environment in outdoor public spaces impacts the use of such spaces. Thermal adaptation, which involves physiological, psychological and behavioral factors, also plays an important role in assessment of thermal environments by users. Given that these issues have rarely been addressed for outdoor environments in hot and humid regions, this study examines user thermal comfort in a public square in Taiwan. Physical measurements were taken and a questionnaire survey was used to assess the thermal comfort of subjects. The number of people visiting the square was also counted. Analytical results indicate that the thermal comfort range and neutral temperature of subjects was higher than those of people in a temperate region. Additionally, local subjects preferred a cool temperature and weak sunlight, and adapted to thermal environments by seeking shelter outdoors. Analytical results confirm the existence of thermal adaptation and illustrate the characteristics of, and variances in, thermal adaptation. During the cool season, the number of people visiting the square increased as the thermal index value increased. However, the number of people frequenting the square decreased as the thermal index increased during the hot season. These experimental results were compared with those for temperate regions, indicating that the human energy balance model cannot fully explain the influence of climate on use of public spaces; that is, psychological and behavioral factors also play important roles in outdoor thermal comfort. Study findings also elucidate design of outdoor public spaces in hot and humid regions.     

Adaptive thermal comfort in primary school classrooms: Creating and validating PMV-based comfort charts

In this research the thermal comfort and thermal comfort parameters for children in primary school classrooms has been investigated. Actual thermal sensation and clothing insulation of children (age 9–11) in non-air-conditioned classrooms in three different schools in the Netherlands have been obtained. Results are available for a total of 24 days, covering winter, spring and summer conditions (year 2010). Questionnaires have been applied to obtain the actual thermal sensation and clothing insulation in the morning and afternoon of regular school days. In this period physical parameters (temperature, relative humidity, etc.) were recorded as well in order to derive the PMV.     

Pedestrian comfort using clothing values and body temperatures

Outdoor human comfort in an urban environment may be affected by a wide range of weather and human factors. The paper describes a research study investigating the complex relationship between physical and psychological parameters on human comfort levels. The study determined that the air temperature and the wind speed have a clear influence on the human comfort level while the solar radiation and relative humidity do not show a strong relationship. The effects of adaptation were shown clearly using over 8000 data sets with clear differences between five European countries. The importance of adaptation was further shown by the low correlation values between comfort and certain meteorological parameters. It is suggested that the subjective parameter of human comfort level is not well suited to determine guidelines for the design of outdoor spaces. Controlled tests in a wind tunnel have shown that the skin temperature (forehead and hand) has the potential to be used as a surrogate for comfort. With respect to the climatic variations outlined in this paper, it was discovered that lower forehead temperatures resulted in lower comfort values nearly independent of the meteorological parameters. Therefore, in the current study it is found that the skin temperature may be used as an objective parameter to determine human outdoor comfort levels although further tests will be necessary.     

Bayesian adaptive comfort temperature (BACT) of air-conditioning system in subtropical climate

Indoor thermal climate is an important issue affecting the health and productivity of building occupants. In the designing of commercial air-conditioning systems, it is believed that the conventional fixed temperature set point concept is limited because indoor comfort temperature depends on the business culture, such as the nature of activities and dress code of occupants, etc. Researchers have been interested in investigating adaptive temperature control for a realistic in-situ control of comfort. Unfortunately, those studies put great emphasis on energy saving opportunities and sometimes might result in thermal discomfort to individuals. This study argues that complaints of thermal discomfort from individuals, despite representing only a small portion of the population, should not be ignored and can be used to determine the temperature setting for a population in air-conditioned environment. In particular, findings of a new notion of Bayesian adaptive comfort temperature (BACT) in air-conditioned buildings in a humid and subtropical climate like Hong Kong are reported, and the adaptive interface relationship between occupants’ complaints of thermal discomfort and indoor air temperature is determined. This BACT algorithm is intended to optimise the acceptance of thermal comfort, as determined by physical measurements and subjective surveys.     

Long-term field survey on thermal adaptation in office buildings in Japan

A long-term field survey was conducted with six buildings in order to investigate how the occupants adapt to the indoor climate in office buildings in Japan. More than 5000 questionnaires and corresponding indoor temperatures were collected. Clothing adjustment was observed to be related to outdoor temperature and indoor temperature, as well as dress codes. No considerable differences were found on the thermal perceptions between two groups of buildings, which provided different levels of opportunity for controlling indoor climate. With both groups, the preferred SET* was always close to 26 °C. The comfort temperature was estimated from the results of clothing adjustment and the preferred SET*. The gradient of the comfort temperature to outdoor temperature was found to be between the adaptive model for centralized HVAC and for natural ventilation. It could be caused by that the major part of the occupants in the present study had more opportunity to control their thermal conditions than in the centralized HVAC buildings (i.e. operable windows, controllable HVAC or personal fans).     

Effect of personal and microclimatic variables on observed thermal sensation from a field study in southern Brazil

Urban climate, which is influenced by land use patterns, heat-generating activities, and the physical texture of urban fabric, has a great impact on outdoor comfort as well as on a building’s energy consumption. A climate-responsive urban planning can provide optimal, comfortable thermal conditions not only for the permanence of humans in outdoor spaces but also reducing the need of air conditioning systems in buildings. The purpose of this article is to present results of an outdoor comfort research with passers-by in downtown Curitiba, Brazil (25°31′S, 917m elevation). Urban locations have been monitored regarding standard comfort variables: air temperature and humidity, wind speed and globe temperature. Alongside the quantitative assessment of comfort conditions, a survey of pedestrian’s thermal comfort perception according to ISO 10551 was carried out on each monitoring campaign by means of questionnaires with the local population. As a whole, from fourteen monitoring campaigns using a couple of weather stations, beginning on January 9 through August 12, 1654 valid comfort votes were obtained. In this paper, we perform a data consistency check, evaluating the relationship between personal (gender and age of respondents) and objective, microclimatic (comfort variables) factors on observed thermal sensation.     

Adaptive comfort model for tree-shaded outdoors in Taiwan

Tree-shaded outdoors can reduce the heat effect by ameliorating the microclimate and enhancing the human thermal comfort outdoors; for this reason, they are main places for rest, recreation and social activity in Taiwan's cities. Field comfort surveys of 3839 interviewees were conducted in tree-shaded spaces throughout a year. The aims were to obtain a better understanding of human thermal comfort response outdoors and to propose an adaptive comfort model for tree-shaded spaces. A comfort zone, centering on neutral operative temperature which is an empirically derived linear function of mean monthly outdoor temperature, of 6 °C for 90% acceptability and 8 °C for 80% acceptability was suggested for tree-shaded spaces from surveyed data, adding that a non-linear function of the temperature difference between actual operative temperature and neutral operative temperature was established that aims to predict the percentage of heat or cold discomfort at a particular outdoor thermal condition. An application of the established adaptive comfort model on an actual tree-shaded space was demonstrated to show its practicality in long-term evaluation of a particular thermal environment.     

Quantifying the relevance of adaptive thermal comfort models in moderate thermal climate zones

Standards governing thermal comfort evaluation are on a constant cycle of revision and public review. One of the main topics being discussed in the latest round was the introduction of an adaptive thermal comfort model, which now forms an optional part of ASHRAE Standard 55. Also on a national level, adaptive thermal comfort guidelines come into being, such as in the Netherlands. This paper discusses two implementations of the adaptive comfort model in terms of usability and energy use for moderate maritime climate zones by means of literature study, a case study comprising temperature measurements, and building performance simulation. It is concluded that for moderate climate zones the adaptive model is only applicable during summer months, and can reduce energy for naturally conditioned buildings. However, the adaptive thermal comfort model has very limited application potential for such climates. Additionally we suggest a temperature parameter with a gradual course to replace the mean monthly outdoor air temperature to avoid step changes in optimum comfort temperatures.     

Derivation of the adaptive equations for thermal comfort in free-running buildings in European standard EN15251

The equation for thermal comfort for buildings in the free-running mode (Annexe A2) in European Standard EN15251 rests on the data collected in the EU project Smart Controls and Thermal Comfort (SCATs). Many of these data were from naturally ventilated office buildings which were in free-running mode outside the heating season. Using the data from these buildings a relationship between indoor comfort and outdoor climate was developed for free-running buildings. This paper describes the data and the methods of analysis used to estimate the comfort conditions in the variable environment of free-running buildings. The paper also describes how the indoor comfort conditions were related to the running mean of the outdoor temperature, and addresses the effects of air movement and humidity. The paper considers the proportions of people likely to be comfortable if the temperature differs from the neutral temperature. The differences between the adaptive comfort charts in EN15251 and ASHRAE 55-2004 are discussed.     

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.     

Thermal diary: Connecting temperature history to indoor comfort

To explore the relationship between thermal history and indoor comfort, surveys and measurements were conducted in Seoul, Korea and Yokohama, Japan. Fifty-two subjects were recruited from university campuses in Seoul and Yokohama during the hot season in August 2002. To collect information regarding people's daily thermal history, background questions (a thermal diary) were completed by subjects during the 24 h prior to entering in a climate chamber. Subjects changed into uniform clothing ensembles and complete thermal diary questions just prior to entering the chamber which was pre-conditioned to 28 °C and 50% relative humidity. Subjects entered the chamber and completed a set of thermal comfort questions at 10-min intervals for 1 h. Thermal history, prior to the chamber experiment, influenced the thermal sensation in chamber. Though the physical conditions in the climate chamber were identical (28 °C, 50% rh), Yokohama subjects responded with cooler thermal sensations than Seoul subjects. These subjects experienced hotter weather conditions (than the Seoul subjects) and voted that they felt cooler than the Seoul subjects who experienced cooler temperatures prior to entering the chamber. It was also found that subjects who use air-conditioning at home responded with warmer thermal sensations than the subjects who did not use air-conditioning. These results indicate that there is a strong interaction and influence of our experience with outdoor weather and our indoor thermal comfort.     

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。     

Impact of adaptive comfort criteria and heat waves on optimal building thermal mass control

This article investigates building thermal mass control of commercial buildings to reduce utility costs with a particular emphasis on the individual impacts of both adaptive comfort criteria and of heat waves. Recent changes in international standards on thermal comfort for indoor environments allow for adaptation to the weather development as manifested in comfort criteria prEN 15251.2005 and NPR-CR 1752.2005 relative to the non-adaptive comfort criterion ISO 7730.2003. Furthermore, since extreme weather patterns tend to occur more frequently, even in moderate climate zones, it is of interest how a building's passive thermal storage inventory responds to prolonged heat waves. The individual and compounded effects of adaptive comfort criteria and heat waves on the conventional and optimal operation of a prototypical office building are investigated for the particularly hot month of August 2003 in Freiburg, Germany. It is found that operating commercial buildings using adaptive comfort criteria strongly reduces total cooling loads and associated building systems energy consumption under conventional and building thermal mass control. In the case of conventional control, total operating cost reductions follow the cooling loads reductions closely. Conversely, the use of adaptive comfort criteria under optimal building thermal mass control leads to both lower and slightly higher absolute operating costs compared to the optimal costs for the non-adaptive ISO 7730. While heat waves strongly affect the peak cooling loads under both conventional and optimal building thermal mass control, total cooling loads, building energy consumption and costs are only weakly affected for both control modes. Passive cooling under cost-optimal control, while achieving significant total cost reductions of up to 13%, is associated with total energy penalties on the order of 1–3% relative to conventional nighttime setup control. Thus, building thermal mass control defends its cost saving potential under optimal control in the presence of adaptive comfort criteria and heat waves.     

Thermal comfort and use of thermostats in Finnish homes and offices

Thermal comfort and use of thermostats in homes and office rooms were examined by a quantitative interview survey with a nationally representative sample in Finland. The total number of respondents was 3094. The results show that thermal comfort levels are lower in offices than in homes. People feel cold and hot more often in offices than in homes during both the winter and summer seasons. The perceived control over room temperature is remarkably low in offices. Higher thermal comfort levels and perceived control in homes are supported by greater adaptive opportunities. In offices people have fewer opportunities to control the thermal environment, people deal worse with thermostats, and people have lower opportunities to adapt to different thermal environments.     

Thermal comfort analysis of earth-sheltered buildings: The case of meymand village,Iran

Vernacular buildings are known for their localized passive settings to provide comfortable indoor environment without air conditioning systems. One alternative is the consistent ground temperature over the year that earth-sheltered envelopes take the benefit; however, ensuring annual indoor comfort might be challenging. Thus, this research monitors the indoor thermal indicators of 22 earth-sheltered buildings in Meymand, Iran with a warm-dry climate. Furthermore, the observations are used to validate the simulation results through two outdoor and indoor environmental parameters, air temperature and relative humidity during the hottest period of the year. Findings indicated that the main thermal comfort differences among case studies were mainly due to their architectural layouts where the associated variables including length, width, height, orientation, window-to-wall ratio, and shading depth were optimized through a linkage between Ladybug-tools and Genetic Algorithm (GA) concerning adaptive thermal comfort model definition and could enhance the annual thermal comfort by 31%.