Thermal comfort evaluation of naturally ventilated public housing in Singapore

Field survey was conducted to evaluate thermal comfort perception of the occupants in naturally ventilated public housing in Singapore. Thermal acceptability assessment was performed to find out whether the naturally ventilated indoor environment meets the ASHRAE Standard-55's 80% acceptability criteria. The study investigated whether thermal perception was influenced by different sessions of the day, building height, and flat types. Comparative analysis of thermal sensation and thermal comfort votes revealed that a high proportion of people experiencing sensations of +2,+3 still found the conditions to be comfortable. The survey also examined the adaptive behavior of the occupants in the usage of climatic control such as windows, fans and air-conditioning to modify the indoor environment.     

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。     

Field study on occupants’ thermal comfort and residential thermal environment in a hot-humid climate of China

This paper discusses thermal comfort inside residences of three cities in the hot-humid climate of central southern China. Only a few thermal comfort studies have been performed in hot-humid climates and none in Central Southern China. Field sampling took place in the summers of 2003 and 2004 by obtaining 110 responses to a survey questionnaire and measuring environmental comfort variables in three rooms in each of 26 residences. The objectives are to measure and characterize occupant thermal perceptions in residences, compare observed and predicted percent of dissatisfied and discern differences between this study and similar studies performed in different climate zones. Average clothing insulation for seated subjects was 0.54 clo with 0.15 clo of chairs. Only 48.2% of the measured variables are within the ASHRAE Standard 55-1992 summer comfort zone, but approximately 87.3% of the occupants perceived their thermal conditions acceptable, for subjects adapt to prevailing conditions. The operative temperature denoting the thermal environment accepted by 90% of occupants is 22.0–25.9°. In the ASHRAE seven-point sensation scale, thermal neutral temperature occurs at 28.6°. Preferred temperature, mean temperature requested by respondents, is 22.8°. Results of this study can be used to design low energy consumption systems for occupant thermal comfort in central southern China.     

Indoor thermal environment evaluations and parametric analyses in naturally ventilated buildings in dry season using a field survey and PMVe-PPDe model

The PMV model predicts thermal sensation well in HVAC buildings while it predicts a warmer thermal sensation than the occupants actually feel in naturally ventilated buildings. For using PMV model to predict thermal sensation well in a naturally ventilated building, the extended PMV model (PMVe) including an expectancy factor (e) and PMV was proposed by Fanger. Besides, calculations of PMV are too complex to be applied in practice. To obtain simple and applicable correlations, taking Qujing of Yunnan province, China, as example, a dry season (6-month) field measurement was conducted in a naturally ventilated residential room. Based on the collected data, PMVe values were calculated by using Newton’s iterative method. It is shown that the PMVe values approximately vary from −1.3 to 0.20 and the indoor thermal environment is somewhat discomfortable on some cloudy or rainy days. Parameters relationships and indoor air temperature gradients (vertical and horizontal) were also studied by using linear regression technique and quadratic polynomial fit technique. Numerous correlations with high relativities have been developed. It is convenient to use these results to evaluate the indoor thermal environment in naturally ventilated buildings under similar climatic conditions.     

焦作夏季居住建筑人体热舒适现场研究

采用环境参数测量与问卷调查同步进行的方式,研究了混合供冷模式下人们的热舒适性。结果显示,该地区夏季实测热中性温度为27.7℃,预测热中性温度为25.4℃,由热感觉法和直接询问法得到的80%可接受温度范围的上限分别为28.8℃和29.2℃,由这两种方法得到的期望温度分别为27.4℃和24.0℃;在混合供冷模式下,由于存在由空调环境进入非空调环境的情况,所以对热环境的不满意率要高于自然通风状态,可接受温度上限比自然通风状态低。     

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.     

Experimental study of the influence of anticipated control on human thermal sensation and thermal comfort

To investigate whether occupants’ anticipated control of their thermal environment can influence their thermal comfort and to explain why the acceptable temperature range in naturally ventilated environments is greater than that in air‐conditioned environments, a series of experiments were conducted in a climate chamber in which the thermal environment remained the same but the psychological environment varied. The results of the experiments show that the ability to control the environment can improve occupants’ thermal sensation and thermal comfort. Specifically, occupants’ anticipated control decreased their thermal sensation vote (TSV) by 0.4–0.5 and improved their thermal comfort vote (TCV) by 0.3–0.4 in neutral‐warm environment. This improvement was due exclusively to psychological factors. In addition, having to pay the cost of cooling had no significant influence on the occupants’ thermal sensation and thermal comfort in this experiment. Thus, having the ability to control the thermal environment can improve occupants’ comfort even if there is a monetary cost involved.     

Thermal comfort for naturally ventilated residential buildings in Harbin

This field study was conducted during summer 2009 in Harbin, northeast of China in order to investigate human responses to the thermal conditions in naturally ventilated residential buildings in cold climate. We visited 257 families in six residential communities and collected 423 sets of physical data and subjective questionnaires. The neutral temperature is 23.7 °C, with the clothing insulation of 0.54 clo. The neutral temperature in Harbin is lower than neutral temperatures in warm climates by others, which is in accordance with the thermal adaptive model. 80% of the occupants can accept the air temperature range of 21.5-31.0 °C, which is wider than the summer comfort temperature limits by the adaptive model. The preferred temperature range fell between 24.0 °C and 28.0 °C. About 57.9% of the subjects voted “no change” with the humid range of 40% and 70%. 61.5% of the occupants voted “no change” with the air velocity within the range of 0.05-0.30 m/s. In summer, occupants preferred air velocity of lower than 0.25 m/s even at higher indoor temperature, which is different from the other field studies. The Harbin occupants in naturally ventilated dwellings can achieve thermal comfort by operable windows instead of running air-conditioners.     

我国湿热地区人群基础热舒适反应研究(3):冬夏对比分析

沿用经典热舒适研究方法,对我国湿热地区自然通风环境受试者分别进行夏季和冬季气候室实验,并对其心理反应与生理反应作冬夏季对比,得到其热反应的季节性变化特征为:与夏季相比,冬季的热感觉保持不变,但热舒适度与可接受度在低温环境显著降低,而在高温环境显著升高;心率显著增加,皮肤温度有所升高,在高温环境下的皮肤湿润度有所降低.季节性变化特征为湿热地区人群心理适应与生理习服提供了重要证据.     

我国湿热地区自然通风建筑热舒适与热适应现场研究

在2008—2009年为期1年的广州某高校自然通风建筑现场调研的基础上,对23周共计921人次的调研数据在热环境、人体热反应及适应行为等方面进行了分析,得到了我国湿热地区典型自然通风建筑的室内热环境全年变化特征,获取了热感觉与标准有效温度的确定关系,验证了修正的PMV模型的适用性,分析得到我国湿热地区自然通风建筑的期望因子为0.8,同时获得了调整服装、开窗与使用风扇等适应行为的变化规律。     

Study on the thermal performance of the Chinese traditional vernacular dwellings in Summer

Based on the field measurements of the thermal environment parameters and a long-term auto-recorder of the indoor and outdoor temperature at four typical traditional vernacular dwellings at Wannan area in summer, some wrong viewpoints about Chinese traditional vernacular dwellings are clarified. Also, with the analysis of the fine structures design such as the dooryard, the structure of the double-pitched roof and the eaves by the measurements of temperature, wind velocity, etc. some design principles of the traditional vernacular dwellings in Wannan area are revealed, of which sun shading and insulation are of great importance while the natural ventilation is just considered as an auxiliary approach. So the strategy of ventilation design is to restrain the natural ventilation at daytime and to boost it at night. Moreover, the thermal sensation votes (TSV) of the occupants and the predicted mean votes (PMV) are compared and the evaluation standard in a naturally ventilated environment is also discussed.     

北京校园建筑夏冬两季室内热舒适性现场调查研究

测试了空气温度、平均辐射温度、相对湿度、风速等环境参数,采用问卷的形式调查了受试者的主观热感觉,建立了热感觉与室内操作温度的对应关系。在夏季,人们对偏热环境的耐受力强于PMV预测结果;在冬季,人体对于偏冷环境具有适应性,若室内温度偏高,人会感觉不适,实际热感觉高于PMV预测值;由于供暖条件的差异,长期生活在我国南方的人冬季对于偏冷环境的适应性要强于北方人。     

Using the adaptive model of thermal comfort for obtaining indoor neutral temperature: Findings from a field study in Hyderabad,India

There is a dearth of thermal comfort studies in India. It is aimed to investigate into the aspects of thermal comfort in Hyderabad and to identify the neutral temperature in residential environments. This was achieved through a thermal comfort field study in naturally ventilated apartment buildings conducted during summer and monsoon involving over 100 subjects. A total of 3962 datasets were collected covering their thermal responses and the measurement of the thermal environment. The comfort band (voting within –1 and +1), based on the field study, was found to be 26–32.45°C, with the neutral temperature at 29.23°C. This is way above the indoor temperature standards specified in Indian Codes. It was found that the regression neutral temperature and the globe temperature recorded when voting neutral converged when mean thermal sensation of the subjects was close to 0. This happened during the period of moderate temperature when the adaptive measures were adequate. The indoor temperatures recorded in roof-exposed (top floor) flats were higher than the lower floors. The thermal sensation and preference votes of subjects living in top floors were always higher. Consequently, their acceptance vote was also lower. It was found that the subjects living in top floor flats had a higher neutral temperature when the available adaptive opportunities were sufficient. This was due to their continuous exposure to a higher thermal regime due to much higher solar exposure. This study calls for special adaptive measures for roof-exposed flats to achieve neutrality at higher temperature.     

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.     

Thermal comfort of rural residents in a hot–humid area

ABSTRACT

The thermal comfort of rural residents in China is studied to improve their living conditions and safeguard agricultural development. The present study recruited 30 healthy young people (50% male and 50% female) from rural areas of the hot and humid region of China and exposed them to a wide range of temperatures (20–32°C) and humidities (50% and 70%) in a climate chamber. Both the psychological and physiological responses were observed. The thermal neutral standard effective temperature (SET) was determined to be 26.8°C and the 90% thermal acceptable SET range was 22.9–30.7°C. Mean skin temperature and skin wetness were found to be good predictors for thermal comfort in the neutral-cool and neutral-warm conditions, respectively. When compared with the previous results from similar studies of urban participants living in naturally ventilated buildings, a significant divergence is found. Rural participants reported the same thermal sensation but felt more comfortable and acceptable under identical cool or warm conditions. Rural participants had the same neutral temperature, but a much wider acceptable temperature range. The reason for these differences between rural and urban people may be attributed to differences in local culture, expectations and environmental cognition.     

湖北山区农宅热环境及居民热舒适调查研究

基于2 171份来自湖北山区罗田县农宅冬、夏两季室内外热环境和热舒适问卷,真实再现了当地住宅室内冬季寒冷、夏季湿热的恶劣热环境和当地居民强大的热适应能力;并通过比较研究发现现有的自然通风状态热舒适评价模型在夏季能较好地预测当地农民的热舒适感受,而在冬季预测能力较低;当地农宅室内适应性热舒适区间与我国现行设计标准也较为吻合。     

Behavioural adaptation and the use of environmental controls in summer for thermal comfort in apartments in India

Building energy use in India is rising phenomenally. Indian codes prescribe a very narrow comfort temperature range (23-26 °C) for summer. Ventilation controls alone consume 47% of total energy in residences. Thermal comfort field studies in Indian residences were not attempted. The author conducted a field study in apartments in Hyderabad, in summer and monsoon seasons in 2008. This paper presents the occupants’ methods of environmental and behavioural adaptation and impediments in using controls.Only about 40% of the occupants were comfortable in summer due to inadequate adaptive opportunities. The comfort range obtained in this study (26.0-32.5 °C), was way above the standard. Fanger's PMV always overestimated the actual sensation.The occupants used many adaptation methods: the environmental controls, clothing, metabolism and many behavioural actions. Use of fans, air coolers and A/cs increased with temperature, and was impeded by their poor efficacy and noise, occupant's attitudes and economic affordability. A/c and air cooler usage was higher in top floors. Behavioural adaptation was better in summer and was restricted in higher economic groups always. Thermal tolerance was limited in subjects using A/cs and resulted in “thermal indulgence”. This study calls for special adaptation methods for top-floor flats.     

Analysis of the microclimatic and human comfort conditions in an urban park in hot and arid regions

Urban parks have complex surface structure that produces an environment with specific microclimatic qualities. These qualities affect the balance of energy of the human body and are applicable to an individual’s thermal perception. They have impacts on using outdoor spaces especially in hot and arid regions. This study investigates users’ thermal comfort in an urban park in Cairo, Egypt. The investigation was carried out during the hot and cold months using subjective surveys and field measurements. The campaign consisted of a subjective survey using questions on the perception of the thermal environmental applying seven-point ASHRAE 55 thermal sensation votes (TSV) in nine different zones in the urban park. At each zone, the thermal environment parameters – air temperature, solar radiation, air relative humidity and wind speed were measured. Through these data, the values of the Physiologically Equivalent Temperature (PET) were calculated in each zone using the RayMan model. The current people clothing and metabolic rate were recorded. The results of the field measurements were compared with judgements about the thermal environment. Results demonstrate that differences in the PET index among these zones due to different sky view factors (SVF) and wind speed. Results revealed an alteration in human comfort sensation between different landscape zones. This paper suggests that the thermal requirements of visitors and qualities of the local climate should be carefully considered when designing landscapes for the future urban parks in the hot and arid regions.     

Evidence base prioritisation of indoor comfort perceptions in Malaysian typical multi-storey hostels

This study focuses on assessing the effects of the indoor climate in typical multi-storey hostels in Malaysia on student occupants through objective, subjective and evidence based prioritisation measurements. The objective measurements consisted of operative temperature; daylight ratio; luminance and indoor noise level. The subjective measurements were sampled from the student occupants' thermal, visual, acoustics and overall indoor comfort votes. The prioritisation measurement using Multiple Linear Regression and Friedman Tests assessed the relationship between physical indoor thermal, visual and acoustics conditions and students' overall indoor comfort perception vote. Findings suggest that subjective sensor ratings were significantly more reliable than objective measurements at predicting overall indoor comfort. Moreover, students living in hostel rooms with projected balconies voted that they were more satisfied with their indoor condition than the ones living in rooms without projected balconies. The results of this study also provide evidence that student occupants were more concerned with their rooms' thermal condition then followed by acoustics and finally visual conditions.     

Field study of a thermal environment and adaptive model in Shanghai

A long-term field investigation was carried out in naturally ventilated residential buildings in Shanghai from April 2003 to November 2004. A total of 1,768 returned questionnaires were collected in the study. This study deals with the thermal sensation of occupants in naturally ventilated buildings and the change in thermal neutral temperature with season. The range of accepted temperature in naturally ventilated buildings is between 14.7 degrees C T(op) and 29.8 degrees C T(op). The results also report the findings of the adaptive comfort model in Shanghai that determines the adaptive relationship of neutral temperature with outdoor air temperature. A long-term field study was carried out in residential buildings in Shanghai to find the relationship between thermal sensation, indoor neutral temperature and outdoor temperature. This paper presents findings of thermal comfort and discusses the more sustainable standard for the indoor climate of residential buildings in Shanghai.