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.     

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.     

自然通风环境下的热舒适分析

鉴于自然通风环境下的PMV实际热舒适调查结果有较明显的偏差，热舒适研究领域提出了两种新的模型：PMV修正模型和适应模型。对这两种模型进行了分析，认为应对自然通风环境和空调稳态环境参数进行更细致的分析，以建立一种适用于自然通风环境的集总参数模型或评价指标。     

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.     

自然通风与节能舒适性分析

介绍了自然通风技术的基本原理与应用形式,从建筑物节能与舒适性两方面探讨了自然通风在建筑物中的应用,指出在自然通风的设计和应用过程中应综合考虑地理气候、建筑物结构和环境调节要求等因素,同时应加强相关技术的研究和开发。     

亚热带地区自然通风体育馆室内热舒适范围

以广州地区自然通风体育馆为研究对象,用问卷和实测的方式分别采集了建筑内运动人群及观众人群的热感觉投票值和室内外热环境参数,初步建立了这两类人群的适应性热舒适模型和对应的热舒适范围。并通过对比,分析了两类人群的适应性热舒适模型和热舒适范围的区别。研究结果表明：自然通风体育馆室内运动人群的热敏感度0.326 6要小于观众人群的热敏感度0.379 9;运动人群和观众人群的中性操作温度都随着室外温度的升高而升高,前者中性操作温度高于后者,差值在0.80~1.48℃之间;运动人群和观众人群热舒适范围的上下限都随着室外温度的升高而升高,前者热舒适范围的下限与后者相似,但是前者热舒适范围的上限比后者高,差值在1.86~2.48℃之间。     

重庆自然通风热舒适模型的建立及热环境评价

在分析国内外自然通风热舒适研究的基础上,结合重庆地区潮湿的气候特点,对现有自然通风热舒适评价模型进行了湿度修正.采用电子温湿度记录仪对重庆地区村镇典型住宅的室内外热湿参数进行了全年监测,并利用该模型对村镇住宅的室内热环境进行了评价.分析表明,村镇住宅室内和室外相对湿度高于70％的时间分别占全年总时间的95.4％和87.2％,室内温度高于28℃且相对湿度高于70％的时间达1 196 h;全年舒适时间为3 838 h,占全年总时间的43.8％;现有评价模型与修正模型的舒适时间相差405 h,其中空调季相差342h,且温度越高,相对湿度对热舒适的影响越大,说明在温度较高时应考虑相对湿度对热舒适的影响,但修正模型的可靠性还需进一步验证.     

Building and indoor environmental quality assessment of Nigerian primary schools: A pilot study

A total of 15 classrooms went through on‐site assessments/inspections, including measurements of temperature (T), and concentrations of carbon monoxide (CO) and carbon dioxide (CO₂). In addition, the level of surface biocontamination/cleaning effectiveness was assessed by measuring adenosine triphosphate (ATP) levels on students' desks. Based on the data, the quality of facilities in the buildings was low. Classroom occupancy exceeded ASHRAE 50 person/100 m² standard in all cases indicating overcrowding. However, concentrations of CO₂ remained below 1000 ppm in most classrooms. On the other hand, indoor T was above the recommended levels for thermal comfort in all classrooms. Maximum indoor CO was 6 ppm. Median ATP concentrations on the desk tops were moderately high in all schools. The use of open incinerators and power generator sets near classrooms, which was suspected to be the main source of CO, should be discouraged. Improved hygiene could be achieved by providing the students access to functioning bathroom facilities and cafeteria, and by effective cleaning of high contact surfaces such as desks. Although ventilation seems adequate based on CO₂ concentrations, thermal comfort was not attained especially in the afternoon during extreme sunlight. Therefore, installing passive and/or mechanical cooling systems should be considered in this regard.     

基于风速补偿的自然通风房间热舒适性模拟研究

为获得自然通风条件下室内的热舒适评价方法,利用Fluent软件,根据杭州市典型室外气象参数确定边界条件,模拟居住建筑室外绕流场、室内通风场和温度场的分布规律;运用基于风速补偿的热适应性评价模型分析室内热舒适状况,并将此法与PMV模型结果对比,表明前者定义舒适的阈值较小,且正向偏离较大,后者则能较好反映自然通风房间的热环境。     

Development of an adaptive window-opening algorithm to predict the thermal comfort,energy use and overheating in buildings

This investigation of the window-opening data from extensive field surveys in UK office buildings demonstrates: (1) how people control the indoor environment by opening windows; (2) the cooling potential of opening windows; and (3) the use of an ‘adaptive algorithm’ for predicting window-opening behaviour for thermal simulation in ESP-r. It was found that when the window was open the mean indoor and outdoor temperatures were higher than when closed, but it was shown that nonetheless there was a useful cooling effect from opening a window. The adaptive algorithm for window-opening behaviour was then used in thermal simulation studies for some typical office designs. The thermal simulation results were in general agreement with the findings of the field surveys. The adaptive algorithm is shown to provide insights not available using non adaptive simulation methods and can assist in achieving more comfortable, lower energy buildings while avoiding overheating.     

Adaptive-rational thermal comfort model: Adaptive predicted mean vote with variable adaptive coefficient

Thermal adaptations, as feedbacks of occupants to physical stimuli, extend thermal comfort zone thereby reducing building energy consumption effectively. The rational approach models thermal comfort from the perspective of the body's heat balance, but is limited in explaining the thermal adaptations. The adaptive approach of modeling thermal comfort can fully account for the thermal adaptations, but ignores the body's heat balance. To improve thermal comfort prediction, this study proposes an adaptive-rational thermal comfort model, that is, an adaptive predicted mean vote with a variable adaptive coefficient (termed as arPMV). By linearly linking the negative feedback effects of the thermal adaptations to the ambient temperature according to the adaptive approach, the variable adaptive coefficient is linearly related to the reciprocal of the ambient temperature with two constants. The variable adaptive coefficient is determined by explicitly quantifying the two constants as the functions of the predicted mean vote, thermal sensation vote, and ambient temperature. The proposed arPMV is validated for naturally ventilated, air-conditioned, and mixed-mode buildings, with the mean absolute error and the robustness of the thermal sensation prediction reduced by 24.8%-83.5% and improved by 49.7%-83.4%, respectively.     

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.     

Impact of adaptive thermal comfort on climatic suitability of natural ventilation in office buildings

In earlier work [1], NIST developed a climate suitability analysis method to evaluate the potential of a given location for direct ventilative cooling and nighttime ventilative cooling. The direct ventilative cooling may be provided by either a natural ventilation system or a fan-powered economizer system. The climate suitability analysis is based on a general single-zone thermal model of a building configured to make optimal use of direct and/or nighttime ventilative cooling. This paper describes a new tool implementing this climate suitability methodology and its capability to consider an adaptive thermal comfort option and presents results from its application to analyze a variety of U.S. climates. The adaptive thermal comfort option has the potential to substantially increase the effectiveness of natural ventilation cooling for many U.S. cities. However, this impact is very dependent on the acceptable humidity range. If a dewpoint limit is used, the increase is significant for a dry climate such as Phoenix but much smaller for humid climates such as Miami. While ASHRAE Standard 55 does not impose a limit on humidity when using the adaptive thermal comfort option, the necessity of limiting humidity for other reasons needs to be considered.     

自然通风热舒适探讨

介绍了人体热舒适评价指标及自然通风热舒适评价指标,探讨了建立适合我国自然通风热舒适的评价模型,对进一步研究自然通风热舒适有一定的指导意义。     

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.     

通风降温建筑室内热环境模拟及热舒适研究

将热舒适评价标准ＰＭＶ／ＰＰＤ模型与建筑动态热模拟及计算流体动力学（ＣＦＤ）模拟相结合，分别对重庆地区自然通风房间和埋管送风通风房间进行了室内气候及热舒适性模拟与分析，结果表明，埋管系统通风降温可以改善炎热地区的室内热舒适性。     

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.     

昆明地区夏季居住建筑室内热环境测试及热舒适调查

对昆明市200户住宅夏季室内热环境参数进行了实测,并进行了现场问卷调查。分析了室内温度、相对湿度、风速、人员服装热阻的分布频率,统计得出了昆明地区住宅夏季室内热环境及人体热舒适的基本情况,并分析了室内热环境改善措施。调查发现,昆明市居民夏季普遍通过开窗进行自然通风以降低室内温度,在非空调条件下约有90%的居民的热感觉在舒适范围内。