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Thermal comfort in buildings with split air-conditioners in hot-humid area of China

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Abstract

a b s t r a c t Occupants' thermal sensations, perceptions and behaviors in buildings with split air-conditioners in hot-humid area of China were systematically investigated for a whole year with longitudinal design. Thirty college students, naturally acclimatized to local climate and well experienced with the indoor envi-ronments of buildings, participated in the present study. They reported their thermal sensations, perceptions and behaviors in questionnaires while their ambient environmental variables were measured. A close match of indoor and outdoor climate was found. Thermal sensation was found to be a linear function of ET* or SET and thermal neutrality was 25.6 C in ET* or 24.9 C in SET. The central five categories of the ASHRAE 9-point thermal sensation scale were found to be acceptable and the 90% (80%) acceptable range of thermal environment was found to be 20.6e30.5 C (16.9e34.2 C) in ET*. The adaptive behaviors of clothing adjustment, opening windows and using fans were found to be closely correlated with indoor ET*. The split air-conditioners were used from May to October and turned on most often at midnight with indoor air temperature of 30.1 C and setting temperature of 26.1 C. Compared with those from naturally ventilated buildings, the occupants from buildings with split air-conditioners kept indoor climates much cooler, used adaptive opportunities much earlier and perceived their ambient environments more sensitively and rigidly.

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... The empirical finding reported by Zhang et al. [52] is selected as the next test case for evaluating the proposed PMV þ model. Zhang et al. [52] investigated the thermal sensation in buildings with split In Fig. 8 the results of the proposed model are compared against the original PMV, and PMV new model and the reported experimental data by Zhang et al. [52]. ...
... The empirical finding reported by Zhang et al. [52] is selected as the next test case for evaluating the proposed PMV þ model. Zhang et al. [52] investigated the thermal sensation in buildings with split In Fig. 8 the results of the proposed model are compared against the original PMV, and PMV new model and the reported experimental data by Zhang et al. [52]. As can be seen in this figure, the performance of the proposed new model in predicting the thermal sensation of people in hot and humid environments is significantly improved compared to previous models. ...
... The empirical finding reported by Zhang et al. [52] is selected as the next test case for evaluating the proposed PMV þ model. Zhang et al. [52] investigated the thermal sensation in buildings with split In Fig. 8 the results of the proposed model are compared against the original PMV, and PMV new model and the reported experimental data by Zhang et al. [52]. As can be seen in this figure, the performance of the proposed new model in predicting the thermal sensation of people in hot and humid environments is significantly improved compared to previous models. ...
Article
Adjusting clothing insulation plays a pivotal role as human behavioral adaptation to the thermal environment. Most widely used thermal comfort models, such as the PMV model, assume that the entire body is uniformly covered by clothing. Using these models in hot and humid environments, where people often wear partially covered clothing, can cause an error in predicting the thermal sensation. The object of the present paper is to investigate the effect of the assumption of whole-body uniform clothing coverage on the error of standard thermal comfort models in hot and humid environments. Investigations were performed using a three-node thermal comfort model in the temperature range of 26 C to 31 C at 50% and 70% relative humidity for three different clothing levels (0.4, 0.6, and 0.8 clo). The results showed that for typical summer clothing (0.6 clo and 80% body surface coverage), ignoring the non-uniformity of clothing insulation distribution can lead to an average of 0.2-to-0.45-unit scale deviation in thermal sensation depending on ambient temperature. This effect is more evident at higher ambient temperatures and humidity. Eventually, a new model was proposed for application in hot and humid environments by considering the non-uniformity of clothing coverage. The model’s performance was evaluated against multiple sets of reported experimental data.
... A survey showed that people in non-naturally ventilated buildings usually keep indoor climates much cooler than residents of naturally ventilated buildings [36]. Zhang et al. [36] stressed further that such people take adaptive measures more often at the early stage to regulate the thermal environment than those in naturally ventilated buildings. ...
... A survey showed that people in non-naturally ventilated buildings usually keep indoor climates much cooler than residents of naturally ventilated buildings [36]. Zhang et al. [36] stressed further that such people take adaptive measures more often at the early stage to regulate the thermal environment than those in naturally ventilated buildings. The study [36] maintained that occupants of non-naturally ventilated buildings are likely to perceive the thermal environment much better than the occupants of naturally ventilated buildings. ...
... Zhang et al. [36] stressed further that such people take adaptive measures more often at the early stage to regulate the thermal environment than those in naturally ventilated buildings. The study [36] maintained that occupants of non-naturally ventilated buildings are likely to perceive the thermal environment much better than the occupants of naturally ventilated buildings. In another study conducted by De Dear et al. [6], the study highlighted that respondents in areas exposed to broader weather variations tend to have higher thermal adaptability than those in more equable weather areas. ...
Article
This paper examines the performance and apparent temperature in cross-laminated timber (CLT) school buildings. The research presents empirical data on the performance and provides the first set of data on apparent temperature in CLT school buildings. The development is in the New England area of the Northeast of the US. The investigation was conducted in the summertime. The principal aim of the investigation is to evaluate the performance, occupants’ comfort, apparent temperature, and other thermal indices concurrently in CLT school buildings. The research intends to understand if occupants of CLT school buildings are susceptible to thermal stress in summer and assess whether apparent temperatures are consistent with sensation. The study also discusses other indices, practical implications, and applications of the outcomes. To achieve the research aim, the study considered the field measurements of variables. Occupants’ comfort is accessed using the PMV and adaptive methods of various comfort standards. During the survey, the development was occupied from 8am-6pm and partly operated from 7pm-7am. The mean temperatures during the occupied and non-occupied periods varied from 22.1°C-22.4°C. The overall RH was 59.2%. The PMV range and sensation showed the occupants were comfortable. Approximately 80% of the users were satisfied with the thermal environment. The temperatures were within the acceptable bands of ASHRAE-55, CIBSE TM52, and EN16798-1 thermal comfort models. The results showed that the apparent temperatures are consistent with the outcomes of the sensation at different periods. The mean indices ranged from 18.8°C-23.5°C. The study recommends that further research should be conducted on occupants’ comfort and heat indices in school buildings during the first few hours of occupation to understand changes that occupants can make to remove unwanted heat from the thermal environment. The study also recommends that various designers should consider heat stress analyses along with thermal comfort assessment at the design phase to determine possible interventions to improve the thermal environment of schools and other buildings.
... Hwang et al. (2006) stated that relative humidity has a less substantial impact on the thermal sensation of people. Zhang et al. (2013) noted that the occupants in school buildings located in hot and humid climates have more tolerance to high temperatures and relative humidity when compared with the occupants in school buildings located in temperate climates. Also, people in non-naturally ventilated buildings are likely to take adaptive actions to regulate the thermal environment than the people in naturally ventilated buildings (Zhang et al., 2013). ...
... Zhang et al. (2013) noted that the occupants in school buildings located in hot and humid climates have more tolerance to high temperatures and relative humidity when compared with the occupants in school buildings located in temperate climates. Also, people in non-naturally ventilated buildings are likely to take adaptive actions to regulate the thermal environment than the people in naturally ventilated buildings (Zhang et al., 2013). Zhang et al., (2013) explained further that people in the non-naturally ventilated spaces are more sensitive with a higher perception of the thermal environment than the people in naturally ventilated areas. ...
... Also, people in non-naturally ventilated buildings are likely to take adaptive actions to regulate the thermal environment than the people in naturally ventilated buildings (Zhang et al., 2013). Zhang et al., (2013) explained further that people in the non-naturally ventilated spaces are more sensitive with a higher perception of the thermal environment than the people in naturally ventilated areas. Serghides et al. (2014) mentioned excessive cooling in school buildings that can lead to low temperatures in summer and excessive heating that can cause elevated temperatures in winter. ...
Chapter
The goal of achieving a smart and sustainable built environment starts with the design, construction, and maintenance of an intelligent and sustainable occupied thermal environment. Such an environment must be designed and constructed to achieve thermal comfort and overall well-being of occupants. This paper presents a field investigation of occupants’ comfort and cold stress in cross-laminated timber (CLT) school buildings during the cold seasons (fall and winter). The study was conducted from October to November 2017 for the fall season and from December 2017 to February 2018 for the winter season. The case study comprises of spaces constructed with structural timber products. The case study is a LEED certified school building. It has been identified as one of the first green school buildings in the Northeast region of the USA. The building explores HVAC systems, and it utilizes ground source heat pumps for heating and cooling. The research employed physical measurements of environmental variables such as temperature, relative humidity (RH), dew-point temperature, air velocity and CO2 level in the selected spaces such as the administrative office, science, and art classrooms and the multi-purpose hall. The sensors were mounted on the internal walls at 1.1 m above the floor to measure the variables at every 60 min throughout the cold seasons. The study also calculated the Wet-Bulb Globe Temperature (WBGT) in the spaces to understand the average cold stress index within the thermal environment. The mean outdoor temperature was 11.3 °C in fall, and 0.5 °C in winter. In the fall season, the results showed that the mean indoor temperature was 21.2 °C. In the same season (fall), the mean RH was 50.7%, and the average dew-point temperature was 9.3 °C. In the winter, the average indoor temperature was 20.5 °C while the average RH was 23.9% and the mean dew-point temperature was −1.9 °C. The overall mean temperatures measured in the spaces during the cold seasons were within the comfort temperature thresholds (20.3 °C/23.9 °C) recommended by ASHRAE. In the fall, the mean RH was within the comfortable range (30–60%). The mean RH value was below the comfortable range in the winter. The study recorded a higher mean temperature, RH and dew-point temperature in the office space than the classrooms and the main hall during the cold seasons. Lower cold stress indexes were also calculated in the multi-purpose hall than the classrooms and office space. The study revealed occupants are more likely to experience cold temperatures in the hall than the office space and classrooms. The difference in the floor level (the main hall is on the lower floor while the classrooms are on the upper floor), hours of occupation (more extended hours of occupation in the office space), and floor area may be the contributing factors to the lower temperatures measured in the hall than the other spaces. By applying the WBGT mathematical model, the research recommends the WBGT of 16.0 °C and 13.7 °C as the cold stress indexes in the building for the fall and winter seasons respectively. Finally, the study recommends a WBGT of 14.9 °C as the average cold stress index in the spaces evaluated in this paper.
... Para ambientes condicionados artificialmente, o Predicted Mean Vote (PMV) ou Voto Médio Estimado (FANGER, 1972) é um método de avaliação de conforto térmico bastante difundido na literatura (CANDIDO; DEAR, 2012;CASTILLA et al., 2011;ZHANG;CHEN;MENG, 2013). O PMV prevê o valor médio dos votos de um grande grupo de pessoas baseado no balanço térmico do corpo humano, em uma escala sétima de sensação térmica, onde +3 é muito quente, +2 é quente, +1 é levemente quente, 0 é neutro (sensação de conforto), -1 é levemente frio, -2 é frio e -3 é muito frio (ASHRAE, 2013;ISO, 2005). ...
... Para ambientes condicionados artificialmente, o Predicted Mean Vote (PMV) ou Voto Médio Estimado (FANGER, 1972) é um método de avaliação de conforto térmico bastante difundido na literatura (CANDIDO; DEAR, 2012;CASTILLA et al., 2011;ZHANG;CHEN;MENG, 2013). O PMV prevê o valor médio dos votos de um grande grupo de pessoas baseado no balanço térmico do corpo humano, em uma escala sétima de sensação térmica, onde +3 é muito quente, +2 é quente, +1 é levemente quente, 0 é neutro (sensação de conforto), -1 é levemente frio, -2 é frio e -3 é muito frio (ASHRAE, 2013;ISO, 2005). ...
... Para ambientes condicionados artificialmente, o Predicted Mean Vote (PMV) ou Voto Médio Estimado (FANGER, 1972) é um método de avaliação de conforto térmico bastante difundido na literatura (CANDIDO; DEAR, 2012;CASTILLA et al., 2011;ZHANG;CHEN;MENG, 2013). O PMV prevê o valor médio dos votos de um grande grupo de pessoas baseado no balanço térmico do corpo humano, em uma escala sétima de sensação térmica, onde +3 é muito quente, +2 é quente, +1 é levemente quente, 0 é neutro (sensação de conforto), -1 é levemente frio, -2 é frio e -3 é muito frio (ASHRAE, 2013;ISO, 2005). ...
Conference Paper
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Energy efficiency programs have increased due to the high-energy demand in buildings, however electricity consumption in commercial buildings from tropical climate regions is still higher than in similar buildings with high energy performance in developed countries. The design of office buildings in Brazil usually do not take into account the appropriate bioclimatic principles, which ultimately raise the building's energy demand, and not always ensures satisfactory environmental quality and thermal comfort for users. This paper analyzed the energy saving potential and thermal comfort improvement for an office building in a tropical climate region. A hypothetical model was simulated with EnergyPlus, using passive bioclimatic strategies (window overhangs, night ventilation and thermal mass for cooling). Thermal comfort was evaluated through Predicted Mean Vote (PMV) index and operative temperature in the rooms. Results for energy consumption, in kWh/m², showed a potential for energy reduction up to 10.1% and an improvement on thermal comfort up to 57% of neutral sensation on occupancy hours.
... From these values, the difference of mean clothing The outdoor air temperature was found to have a significant impact on variations of clothing insulation which is as similar to other studies [18,[72][73][74][75]. It was also related to the indoor temperature similar to the studies done previously [30,76,77]. ...
... The adaptive nature for the clothing insulation were found different even in NV buildings of different part of the world, it might be due to the climatic conditions being different. This study was similar with research from Taiwan [76,80]. The findings indicated that the regression line for all the studies shows similar trend for outdoor as well as the indoor temperature even under different climatic conditions. ...
... In the hot-humid area of China, climate chamber [27] and field [5,28] studies were conducted and a database including 3894 sets of data from urban and rural buildings [29] was established. In addition, the utilization of airflow [30][31][32] and the impact of high humidity [33] were explored. ...
... Air-conditioners are commonly used in the hot-humid area of China during the daytime in autumn when the temperature is still high. Fans are popular supplementary facilities for occupants to cool themselves with sensible airflow and windows are also usually operated by occupants to introduce fresh cool air [28]. In our study, air-conditioners, fans, and windows were controlled by specific modes. ...
... Zhang [56] showed that the common temperature at which residents turned on the air conditioner in hot summer areas was 30.1 °C. Xiao et al. [57] showed that the acceptable indoor thermal comfort temperature for residents in winter is 9.61 °C through measurements and subjective questionnaire evaluation of 30 residential houses in the Changsha area in winter, while DBJ 43-2017 Energy-saving Design Standards for Residential Buildings in Hunan Province [9] stipulates that the design temperatures in summer and winter are 26 °C and 18 °C, respectively. ...
... Xiao et al. [57] showed that the acceptable indoor thermal comfort temperature for residents in winter is 9.61 °C through measurements and subjective questionnaire evaluation of 30 residential houses in the Changsha area in winter, while DBJ 43-2017 Energy-saving Design Standards for Residential Buildings in Hunan Province [9] stipulates that the design temperatures in summer and winter are 26 °C and 18 °C, respectively. Therefore, this study assumes that the design temperatures of air conditioning in summer and winter are 30.1 °C and 9.61 °C (according to studies [56,57], if it reaches the setpoints, most people would turn on the air conditioners), with a 90% probability of air conditioning being turned on, while the comfortable temperatures in summer and winter are 28 °C and 18 °C, respectively, (according to GBT50785-2012, the set points can meet the thermal comfort requirements of 90% of the population), with a 10% probability of being turned on. Using the two-point method, the probabilistic behavioral model of air conditioning (as shown in Table 5) shows that, in summer, U = 26.8 ...
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Occupant behavior has an important impact on building energy consumption, and the accuracy of an occupant behavior model directly affects the reliability of energy consumption simulation results. Ultra-low energy buildings are crucial to achieving building energy conservation and carbon dioxide reduction in China. In order to effectively promote the development of ultra-low energy buildings in Hot Summer and Cold Winter Climate Zones. where most residents adopt a “part-time, part-space” pattern of intermittent energy use behavior, and to solve the problem of poor indoor thermal environments and the high incremental cost of ultra-low energy, the study described in this paper takes Changsha as an example to carry out a multi-objective optimization study on ultra-low energy housing using a probabilistic behavioral model. On the basis of a probability model representing the residents’ actual behavior in Changsha, the optimization objective indicators, key variables and the technology benchmarks for ultra-low energy building were determined, then multi-objective optimization was carried out for a range of energy efficient technologies to obtain the Pareto optimal solutions. The results showed that the set of optimal solutions could reduce energy demand by 50.2 to 60.2% and reduce indoor thermal discomfort time by 3.52–11.09% compared with those of a reference base case, which just meets the requirements of the current design standard for energy efficient domestic buildings. An optimum solution for energy savings and indoor thermal comfort, along with economic costs, was identified, which can assist in decision-making by providing different preferences and provide useful reference for the design of ultra-low energy buildings in Hot Summer and Cold Winter Climate regions.
... °C), Changsha (8.6~30.2 °C), and Israel (8~30 °C) [83][84][85]. Harbin is an exceptionally cold climate city and has an extremely cold winter, with the recorded lowest temperature being −37.7 °C [86]. Therefore, considering this particular outdoor thermal envi- In order to obtain thermal responses and psychological conditions, paper questionnaires were given to 15 subjects ( Figure 3). ...
... • C), Changsha (8.6~30.2 • C), and Israel (8~30 • C) [83][84][85]. Harbin is an exceptionally cold climate city and has an extremely cold winter, with the recorded lowest temperature being −37.7 • C [86]. Therefore, considering this particular outdoor thermal environment, the ASHRAE 7-point scale needs to be extended to a greater-precision scale (11-point scale) [62,86,87]. ...
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It is important for engineering applications that we evaluate the thermal environment based on long-term tracking and investment. Methods merging environmental, physiological, and psychological domains to implement a human-centered approach were applied in this study to assess the outdoor thermal environment in a park. The constant influence of humans in the outdoor environment can change people’s physiological, psychological, and thermal responses. Additionally, the relationship between human physiological, psychological, and thermal factors was explored in this study. The results of this study provide the following findings: (1) In summer, subjects’ skin temperature increased by 0.35 to 2.83 °C during a one-hour outdoor test without shelter, while when tree shade was provided, subjects’ skin temperature dropped by 0.50 to 1.87 °C (except for motion segments). (2) In winter, if subjects stayed outdoors for 1 h, their body segments’ skin temperature dropped by a maximum of 7.93 °C. (3) When subjects went outside, in the early stage, their thermal responses fluctuated for a long time. Therefore, TSV, TCV, and TAV should be measured after they stay outdoors for 45 to 55 min in future studies. (4) Different body segments show different sensitivities to hot or cold. Considering this, a new group of formulas for mean skin temperature calculation are proposed with high accuracy (winter: 0.95; summer: 0.89). (5) Data for the one-hour change in different assessment indicators provide a good viewpoint for park design considering multiple aims such as comfort (TCV), pleasure (EVI), and increasing energy (PFI). Overall, this study took Stalin Waterfront Park as a case study, and some suggestions involving landscaping nodes, space types, and facilities are offered. Moreover, this study provides a novel theory and reasonable method that can be referred to in urban planning and landscape design.
... Zhang et al. [15] Split Air-conditioners Guangzhou 16.9-34.2 • C (80%); 20.6-30.5 • C (90%) Qun et al. [16] Radiation floor heating Suihua 21.9-25.8 ...
... In addition, it has been shown [40] that people living in Guangzhou have experienced hot climates for a long time, have never experienced any severe cold, and require a higher value for thermal neutrality. Zhang et al. [15] studied the thermal comfort of air conditioning in the Guangzhou area and suggested a comfortable temperature range of 20.6-30.5 • C. A higher temperature requirement leads to higher energy consumption. The experiment showed that the thermal neutral temperature and thermal comfort temperature range using radiant floor heating were lower than those of air conditioner heating. ...
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Owing to historical reasons, only a few locations in the Guangdong province use heating to enhance interior thermal conditions. With the variation in climate and increase in people’s lifestyle requirements, winter heating has become increasingly necessary. However, a literature review revealed that only a few studies have investigated the heating requirements during winter in the Guangdong province. In this study, we compared the thermal comfort of radiant floor heating with wall-mounted air conditioner heating. A Guangzhou University climate chamber was used in several investigations. The findings revealed that the thermal neutral temperatures of radiant heating and air conditioner heating were 22.0 °C and 23.0 °C, respectively, about 1 °C variation in temperature. Additionally, in the research on thermal reactions and local skin temperature measurements, the impact of local thermal discomfort on the overall thermal experience was also considered. The findings showed a direct relationship between the local thermal discomfort caused by radiant heating and general thermal sensation. Thermal sensation of the subjects mainly originated from the lower extremities and was significantly affected by Va (air velocity). The relationship between the local thermal discomfort of convective heating and general thermal sensation was weak and mainly caused by the uneven thermal environment. Thus, in south China, for lowering energy usage, radiant floor heating should be used to create an improved indoor thermal environment in winter.
... He et al. [15] conducted a field survey in 25 air-conditioned dormitories in winter; based on the field test and thermal sensation votes in winter, more people voted for cool rather than warm, demonstrating that indoor environment is not entirely satisfactory. Zhang et al. [16] tested the classrooms and dormitories in Guangzhou with RAC and natural ventilation, determining that occupants from buildings with RAC maintained much cooler indoor climates, used adaptive opportunities much earlier, and perceived their ambient environments more sensitively and rigidly. Meanwhile, some field tests have been conducted in residential buildings. ...
... Most of the previous research neglected the indoor non-uniformity in the field test, especially the large scale survey [16] - [18]. Due to the difficulty of home testing and the demands of instruments, the detailed tests, including air speed, indoor temperature variation and distribution, and MRT, are lacked before. ...
Article
Room air conditioners are widely used to improve indoor thermal environments. However, the key factors that affect the performance have not been investigated systematically, which greatly influence the application of room air conditioners. Therefore, a subjective questionnaire and objective field test were conducted in this research. In the subjective questionnaire, the main problems, including the behavior of the occupants, indoor environment, and operation characteristics, were investigated through extensive research. Based on the subjective questionnaire results, field tests combining indoor environmental parameters and energy performance tests were conducted. The obtained results demonstrated that the status was quite different when comparing cooling and heating modes. Both cooling and heating modes improved the overall indoor thermal sensation. Thus, the heating mode results in more thermal complaints based on the thermal non-uniform and start-up stage. Meanwhile, dryness, vertical temperature difference, and draft are the primary requirements during the heating season. By contrast, eliminating drafts and the demand for fresh air are the key requirements for the cooling mode. The energy efficiency of room air conditioner is affected by the non-uniform indoor temperature distribution. This paper focused on both indoor environments and energy efficiency simultaneously, which provides a new research method and the optimization targets for room air conditioners.
... The third section records the current thermal perception of each subject, regarding the measured variable thermal parameters. The questionnaire was designed based on the ASHRAE Standard 55-2017 (ASHARE, 2017) [53] and previous studies [26,54]. The subjective evaluation indices of the outdoor thermal environment were the thermal sensation vote (TSV), thermal preference vote (TPV), and humidity sensation vote (HSV). ...
... As shown, the differences between the metabolic rates of 1 met, 1.2 met, and 2 met were not significant. The main reasons are as follows: firstly, the difference in metabolic rate when people are sitting or standing is small (only 0.2 met), According to one study [54], clothing insulation can increase 0.15 clo while sitting on a chair, higher than that of standing, which may cause MTSV to increase equal to standing condition. Furthermore, while walking, the relative velocity around the body would enhance, which increases heat transfer between the body and the surrounding environment. ...
Article
A suitable outdoor thermal environment can encourage people to partake in outdoor activities, which, in turn, reduces building energy consumption. This can be achieved by accurately predicting the outdoor thermal environment. Most existing prediction models of the outdoor thermal environment focus on the relationship between environmental parameters and human perception, while ignoring the effects of personal factors (e.g., clothing level and metabolic rate). This study explores the relationships between the microclimate environment, personal factors, and human perception of the thermal environment during each season. A field survey was conducted between July 2016 and June 2017, across all four seasons. Thermal environment parameters, including air temperature, relative humidity, wind speed, and globe temperature were recorded and analyzed together with questionnaire survey responses. The results indicated that air temperature has the most significant effect on thermal sensation. In colder or warmer conditions, the mean thermal sensation vote increases with the increase in clothing insulation. Notably, when people kept low metabolic rate activities, including seated and quiet, standing, and walking at 3.2 km/h, the effect of metabolic rate on thermal sensation are negligible. Considering the effect of seasonal differences on the thermal environment parameters, prediction models for each season were obtained using multiple linear regression (the R-squared are 0.560(annual), 0.255 (spring), 0.207 (summer), 0.176 (autumn), 0.145 (winter)). Except for wind speed, all other factors were found to have a positive effect on the prediction models, especially air temperature and mean radiation temperature.
... In recent years, researchers have focused on actual occupant behavior [8][9][10][11], the indoor thermal environment [12,13], and energy conservation strategies [11,14,15]. Zhang et al. [8] investigated the use of RACs in a hot and humid part of China and recorded the thermal environment and preferences for setting of temperature and other conditions. ...
... In recent years, researchers have focused on actual occupant behavior [8][9][10][11], the indoor thermal environment [12,13], and energy conservation strategies [11,14,15]. Zhang et al. [8] investigated the use of RACs in a hot and humid part of China and recorded the thermal environment and preferences for setting of temperature and other conditions. Lu et al. [9] determined the typical temperature-setting patterns for bedrooms in a field test. ...
Article
The field performance of room air conditioners (RACs) directly affects energy consumption. In this study, a long-term field test was conducted in six residential rooms in the Yangtze River Region, China. Using specially developed test equipment, the occupancy pattern, control level, and energy performance factors for constant frequency and inverter RACs were investigated. The field test results showed that the performance of RACs was dependent on the behavior of the occupants and the properties of the service space. The occupancy pattern for RACs was classified as part-time-part-space basis. The control level for constant frequency and inverter RACs indicated that their respective hourly operation ratios and compressor frequency distributions were quite different. Furthermore, based on the compressor energy conservation – compressor volumetric efficiency method, the part load and annual performance were calculated. The results showed that the energy efficiency of inverter RACs was relatively higher with a steady evaporating temperature and small capacity loss. In addition, the actual annual energy efficiency ratios were between 2.38 and 3.83, and the gap between laboratory tests and field test APF ranges from 8.4 to 32.0%, which shows a large difference in the cooling/heating seasonal performance efficiency compared with the laboratory tests.
... In Japan, Rijal et al. [14,22,23] presented a series of field studies in office buildings and developed the local adaptive model. In China, Zhang et al. [24] explored thermal comfort in split air conditioned (SAC) office buildings. ...
... The mean indoor air velocity was 0.17 m/s; the maximum value was 1.27 m/s. The non-uniformities[24] of indoor environment, namely the maximum difference among the values measured at three heights, were calculated. Because the occupants usually used desk fans at different heights, air velocity was the most non-uniformly ...
... Personal control over the indoor environment can alter human thermal comfort sensation [120], and human behavior regulation cannot be ignored in thermal comfort research. People can adjust the human body heat balance in various ways, such as changing clothes, changing the activity levels, turning the air conditioner or fan on/off, etc. [32,121]. The adaptive behaviors of occupants not only play an important role in restoring thermal comfort conditions, but also play a role in creating a comfortable indoor thermal environment [21]. ...
Article
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There have been fruitful publications on thermal comfort of urban residential buildings in China. However, there is a lack of reviews on this topic to perform a comprehensive analysis and find opportunities to meet occupants’ thermal comfort needs while improving building energy efficiencies. This paper addresses this issue by presenting a systematic review on the advancements in research on thermal comfort in urban residential buildings in China. Firstly, two common thermal comfort research approaches, i.e., field studies and laboratory studies, are discussed. Secondly, eleven main thermal comfort evaluation indicators are summarized. Finally, this paper analyzes the thermal comfort survey data from different researchers, discusses the impacts of adaptive behaviors on human thermal comfort, and provides recommendations for future research on urban residential thermal comfort. It was found that people have higher and higher requirements for their indoor thermal environment as time goes by, especially in the winter; the thermoneutral temperature is higher in warmer climate regions in the summer but lower in the winter than in colder climate regions; the thermoneutral temperature tends to increase with the indoor air temperature due to an adaptation to the indoor thermal environment. The outcomes of this paper provide valuable information on thermal comfort behaviors of urban residents in different climate zones in China, which can serve as a resource for the academic community conducting future research on thermal comfort and assist policymakers in enhancing building energy efficiencies without compromising the occupants’ comfort.
... With the progressive understanding of thermal comfort, the establishment of thermal comfort evaluation models has become an important method to study thermal comfort. Some scholars have conducted a large number of empirical studies on various types of buildings and found that each has different comfort conditions, which indicates that residents have different thermal adaptation capabilities in adapting to their environment [17][18][19]. Many research teams in China have conducted indoor thermal environment and thermal comfort studies on their various types of traditional buildings based on the division of climate zones [11,[20][21][22][23][24] and proposed corresponding thermal comfort evaluation models and design optimization strategies. ...
... The Standard New Effective Temperature (SET*) [41] at 1.2 m above the floor was used as the indoor thermal comfort index in the indoor thermal environment regulation calculation. This index can consider indoor air temperature, radiant heat, relative humidity, air velocity, metabolic rate, and clothing rate, and is widely used in indoor thermal comfort assessment [42][43][44]. ...
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Densely built areas with poor thermal insulation suffer from high thermal environmental risks and generally consume high energy in summer. Determining the relationship between density and energy consumption is necessary, particularly when implementing urban heat island (UHI) countermeasures. This study evaluated the effects of density and UHI countermeasures on the energy consumption and indoor thermal comfort of a detached house in a typical densely built wooden house area in Yokohama City, Japan. Three densities and six countermeasures were considered. Annual hourly simulations based on the SCIENCE-Vent thermal environment simulation model yielded the following results: in densely built wooden house areas, the energy consumption and thermal discomfort increased with density. The green roof yielded the largest energy savings in the cooling and heating seasons, demonstrating the highest annual energy savings with 5.7%. Density had little impact on rooftop countermeasures, but the effect of the high-reflectance walls increased with density, and the reduction in annual energy consumption (air conditioning and lighting) is 2.6%, 3.0%, 3.6% in 37%, 47%, and 59% density cases, respectively. The impact of thermal countermeasures on indoor thermal comfort varied according to the thermal control mechanism.
... As of today, numerous studies have focused on indoor thermal comfort in many locations, such as the USA (34,35), Europe (36-38), and Australia (39,40). In the context of China, researchers mainly focused on the northeast (41,42), western (43,44), and coastal (5,(45)(46)(47) regions. Comparatively, indoor thermal comfort in rural dwellings in southwest China received limited attention, although some studies on urban buildings in this region exist (48). ...
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Recently, indoor thermal comfort has received more scholarly attention than ever due to the COVID-19 pandemic and global warming. However, most studies on indoor thermal comfort in China concentrated on urban buildings in the east and north. The indoor thermal comfort of rural dwellers in southwest China is insufficiently investigated. Hence, this study assesses residents' indoor thermal comfort in a rural dwelling in Linshui, obtains the thermal neutral temperature of the rural area, and analyzes the thermal adaptation behavior of rural dwellers. The results reveal that the thermal neutral temperature of rural dwellers is 29.33°C (operative temperature), higher than that presented in previous studies based on the same climate region. Indoor thermal conditions in rural dwellings are relatively harsh, but various thermal adaptation behavior of rural dwellers significantly improve their ability to withstand the harsh conditions. When people live in an environment with a (relatively) constant climate parameter (e.g., humidity), their perception of that parameter seems compromised. Most rural dwellers are unwilling to use cooling equipment with high energy consumption. Therefore, more passive cooling measures are recommended in the design and renovation of rural dwellings.
... Ning et al. [3] conducted a field study and found that the clothing insulation was obviously greater in common heating intensity buildings than high heating intensity buildings. Zhang et al. [4] proved that the adaptive behaviors in split air-conditioned (SAC) buildings are much more sensitive to thermal environment than those in naturally ventilated buildings. Ning et al. [3] indicated that when behavioral adaptation was considered, 2.3% of heating energy would be saved in winter. ...
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It was divided into different modes according to the level of set point temperature (SPT): SPT ≥ 26 °C and SPT < 26 °C. To study behavioral adaptation of different set point temperature modes in office buildings with split air conditioners, a summer field survey was conducted in Zhengzhou and Jiaozuo, China. The results showed that the clothing insulation in high SPT mode was primarily affected by age, whereas the clothing insulation in low SPT mode was influenced by age and indoor temperature. The clothing insulation in high SPT mode was significantly lower than that in low SPT mode, and the air velocity and air movement sensation of subjects in H mode were significantly higher than those in L mode. 1 °C rise in Top could lead to 0.026 m/s increase in air velocity in high SPT mode, but the air velocity in low SPT mode had no relationship with indoor temperature. People’s behavioral adaptation enthusiasm in high SPT mode was greater than that in low SPT mode. The energy consumption can be saved by about 14.8% after considering the adjustment of people’s clothing.
... Into the 1980s through to today when adaptive comfort, personal comfort, and other empirically driven comfort analyses founded on computationally intensive analyses begin to dominate over Fanger's heat balance model, a trend emerges of overconfidence in the error of mean radiant temperature measurements. In a survey of papers that comprise the ASHRAE thermal comfort databases I and II from 1997 through to 2020 [34][35][36][37][38][39][40][41][42][43][44][45][46][47] , there is an average error of 0.70 • C reported for the globe thermometer over the 14 studies with reported errors, which 12 out of 14 times is for a 40 mm or smaller sensor. In addition to the analysis presented in this paper, ISO7726 18 points out that values within 5 • C are impractical to achieve with standard globe thermometers, calling into question the fidelity of modern comfort models with respect to true values for mean radiant temperature. ...
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It is widely accepted that most people spend the majority of their lives indoors. Most individuals do not realize that while indoors, roughly half of heat exchange affecting their thermal comfort is in the form of thermal infrared radiation. We show that while researchers have been aware of its thermal comfort significance over the past century, systemic error has crept into the most common evaluation techniques, preventing adequate characterization of the radiant environment. Measuring and characterizing radiant heat transfer is a critical component of both building energy efficiency and occupant thermal comfort and productivity. Globe thermometers are typically used to measure mean radiant temperature (MRT), a commonly used metric for accounting for the radiant effects of an environment at a point in space. In this paper we extend previous field work to a controlled laboratory setting to (1) rigorously demonstrate that existing correction factors used in the American Society of Heating Ventilation and Air-conditioning Engineers (ASHRAE) Standard 55 or ISO7726 for using globe thermometers to quantify MRT are not sufficient; (2) develop a correction to improve the use of globe thermometers to address problems in the current standards; and (3) show that mean radiant temperature measured with ping-pong ball-sized globe thermometers is not reliable due to a stochastic convective bias. We also provide an analysis of the maximum precision of globe sensors themselves, a piece missing from the domain in contemporary literature.
... On the other hand, for outside temperature, a concept called "running mean temperature", calculated as a ratio based on outside temperature, was used in some thermal comfort evaluation studies. This is supported by the fact that an average of outdoor temperatures weighted in accordance with their distance in the past reflects the thermal experience better than instantaneous monthly average temperature [32,42]. ...
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Thermal comfort can impact the general behavior of the occupants, and considering that humans currently perform 90% of their daily work indoors, it is necessary to improve the accuracy of thermal comfort assessments, and a correct selection of variables could make this possible. However , no review integrates all the variables that could influence thermal comfort evaluation, which relates them to their respective capture devices. For this reason, this research identifies all the variables that influence the thermal comfort of a building, together with the measurement tools for these variables, evaluating the relevance of each one in the research carried out to date. For this purpose, a systematic literature review was carried out by analyzing a set of articles selected under certain defined inclusion/exclusion criteria. In this way, it became evident that the most used variables to measure thermal comfort are the same as those used by the predicted mean vote (PMV) model; however, research focused on the behavior of the occupants has focused on new variables that seek to respond to individual differences in human thermal perception.
... This algorithm would be useful for adaptive control for thermal comfort in large, occupied, air-conditioned spaces. Zhang et al. [11] systematically investigated occupants' thermal sensations in buildings equipped with separate air conditioners in hot, humid areas of China using a longitudinal design. Adjusting clothing choices, opening windows, and adaptive behavior involving the use of fans were found to be closely related to indoor thermal sensations. ...
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... However, the purpose of building climate adaptation is not to precisely control temperature or achieve perfect balance but to strive to create acceptable indoor environments [22]. Despite the existence of perfect artificial heat source environments, people have higher tolerances to simple artificial heat source environments [23,24]. This study's survey showed that the indoor thermal comfort temperature of residents was obviously low under special climatic conditions such as low oxygen. ...
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The improvement of building and living conditions in high-cold areas has always been an issue worthy of attention, but there is currently no research using field survey data for evaluation. The Ganzi region, based in the western plateau of China, is a typical example for such a study. Restricted by factors such as natural conditions and economic level, the winter indoor thermal environment of western plateau houses is generally poor. Taking the new residential houses in the Ganzi region as a case study, the authors of this paper conducted field research and analyses. First, the authors analyzed the construction technology and functional layout of the building through thermal environment testing and investigation; second, the authors analyzed the user’s activity path according to the production and lifestyle; thirdly, the authors comprehensively evaluated the indoor thermal comfort through questionnaires and a predicated mean vote (PMV)-predicted percentage dissatisfied (PPD) evaluation model. The research results showed that: (1) the construction technology, functional layout, and temperature distribution of the new residential building were consistent with the user’s activity path, which could effectively improve thermal insulation ability and thermal comfort; (2) compared to the developed eastern regions, the users in the building showed a stronger tolerance and wider acceptable temperature range in the extreme climate environment; and (3) under certain cooperative work conditions, an indoor temperature of 10–14 °C could meet basic thermal environment requirements and thus lower the limits of the standards. The author’s method was proven to be more resilient than current standards in dealing with climate change. Therefore, this research can provide a practical reference for the improvement of peoples’ living conditions and sustainable development in cold regions and other harsh areas.
... A field study of buildings with split-type air-conditioners were conducted by Zhang et al. [35,36] in the hot-humid area of China. The study lasted an entire year and 1396 sets of raw data were obtained. ...
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Built areas with centralized air conditioning systems have increased intensively in recent years in the hot-humid area of China's mainland. A longitudinal field survey was conducted in a super high-rise building with central air-conditioning system in Guangzhou for a whole year. Forty-four respondents participated in the survey; they were visited three times a week, and thermal comfort data on a large scale with sample size of 3,345 were obtained, containing indoor environmental parameters, personal factors, and subjective responses. The data analysis showed that the indoor environments varied in small operative temperature ranges of 22 °C–27 °C in summer and 19 °C–25 °C in non-summer months, with moderate relative humidity and an air speed of 0.1 m/s. The respondents’ clothing insulation changed in a narrow range of 0.55 clo to 0.60 clo in summer and in a wide range of 0.80 clo to 0.90 clo in non-summer months. The thermal neutral and acceptable operative temperatures were 27.9 °C and 22.0 °C– 29.5 °C in summer, and the thermal neutral temperature was 24.5 °C in non-summer months. A strong preference for a cooler environment was identified in summer. The PMV (Predicted Mean Vote) model was confirmed to be not applicable in, the adaptive thermal comfort theory is also applicable to people in centrally air-conditioned buildings. This study provides a better understanding of thermal comfort in centrally air-conditioned indoor environment, and it is beneficial to practices regarding the evaluation, design, and control of indoor environments for centrally air-conditioned buildings in the hot-humid area of China's mainland.
... For the thermal sensations, perceptions and behaviors of occupants in buildings, Zhang et al. [24] compared split airconditioners with naturally ventilated buildings through a field study. The results showed that the occupants from the buildings using ASHPs maintained the indoor climates much cooler when compared with naturally ventilated buildings, and used adaptive opportunities much earlier and perceived the various of their ambient environments more sensitively and rigidly. ...
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Heating and cooling in buildings accounts for over 20% of total energy consumption in China. Therefore, it is essential to understand the thermal requirements of building occupants when establishing building energy codes that would save energy while maintaining occupants’ thermal comfort. This paper introduces the Chinese thermal comfort dataset, established by seven participating institutions under the leadership of Xi’an University of Architecture and Technology. The dataset comprises 41,977 sets of data collected from 49 cities across five climate zones in China over the past two decades. The raw data underwent careful quality control procedure, including systematic organization, to ensure its reliability. Each dataset contains environmental parameters, occupants’ subjective responses, building information, and personal information. The dataset has been instrumental in the development of indoor thermal environment evaluation standards and energy codes in China. It can also have broader applications, such as contributing to the international thermal comfort dataset, modeling thermal comfort and adaptive behaviors, investigating regional differences in indoor thermal conditions, and examining occupants’ thermal comfort responses.
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The use of an air conditioner (AC) becomes essential, particularly in a hot and humid climate, to provide a comfortable environment for human activities. The setpoint is the agreed temperature that the building will meet, and the use of the lowest setpoint temperature to accelerate the cooling of indoor spaces should be avoided. A comprehensive field study was conducted under various cooling temperature settings in two student activity rooms in a university building in Malaysia, so as to understand respondents’ characteristics and behavior toward AC usage, to estimate the comfort at various indoor temperatures, to develop an adaptive model of thermal comfort in AC spaces, and to compare the comfort temperature with related local and international indoor thermal environmental standards. The findings indicated that water intake and clothing insulation affected personal thermal comfort. Moreover, the mean comfort temperature for respondents was 24.3 °C, which is within an indoor thermal comfort zone of 23–27 °C. The findings suggest that the preference of occupants living in a hot and humid region for lower temperatures means that setting temperatures lower than 24 °C might underestimate the indoor comfort temperature. Additionally, an adaptive relationship can be derived to estimate the indoor comfort temperature from the prevailing outdoor temperature.
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The Chinese government issued a regulation that the cooling set point temperature (SPT) in office buildings cannot be lower than 26 °C. Therefore, SPTs were divided into different modes: SPT≥26 °C and SPT<26 °C. To study the human thermal adaptation of different SPT modes and determine the comfort and energy saving of the policy, a field test and subjective questionnaires were conducted in 21 split air-conditioned (SAC) office buildings during the warm season in the cold zone of China. We measured the environmental parameters and subjects' skin temperatures, and the subjective thermal responses were also investigated. The results showed that 45% of the air conditioner SPTs were less than 26 °C. In the high SPT mode, people's physiological adaptability to the warm environment was stronger, and subjects were more active in reducing clothes and increasing air velocity to improve thermal discomfort. Because the two modes had similar thermal histories and the same perceptual control, in the same SET ranges, no significant differences were found in thermal sensation, acceptability and comfort between the two SPT modes. The effects of long-term indoor thermal history on human thermal adaptation varied with the thermal exposure type, mode and intensity. From the analysis of thermal adaptation, the rationality of the policy was fully proved, and it was determined that SAC office buildings could save 26.4–35.2% of power energy consumption by reasonably increasing SPT in the cold zone. The results can enrich the thermal adaptation theory and provide a theoretical basis for the government's energy-saving policies in SAC office buildings.
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In this paper, both onsite measurements of thermal parameters and a subjective questionnaire of thermal comfort were conducted to investigate thermal comfort of different age groups during the winter season. This study was performed in a rural area of Tianmen, a city of China’s hot summer and cold winter region. Indoor environmental parameters were measured and a total of 1440 questionnaire samples were collected. The volunteers were divided into four groups, i.e., children, young people, middle-aged people and old people. The results indicated that in a cold environment with the temperature below 6 °C, old people were the most sensitive to cold and in a warm environment with the temperature above 19 °C, children were the most sensitive to heat. The neutral SET* (standard effective temperature) of children, young people, middle-aged people and old people in winter was 21.3 °C, 20.8 °C, 23.9 °C and 24.7 °C, which indicated discrepancies of SET* among different age groups. The neutral SET* model of different ages was predicted based on Newton interpolation. This study revealed differences in indoor thermal comfort among different age groups and could provide useful guidance for creating thermal comfortable environment for different ages.
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To create and maintain comfortable indoor environments, predicting occupant thermal sensation is an important goal for architects, engineers, and facility managers. The link between thermal comfort, productivity, and health is common knowledge, and researchers have developed many state-of-the-art thermal-sensation models from dozens of research projects over the last 50 years. In addition to these, the use of intelligent data-analysis techniques, such as black-box artificial neural networks (ANNs), is receiving research attention with the aim of designing building thermal-behavior models from collected data.With the convergence of internet of things (IoT), cloud computing, and artificial intelligence (AI), smart buildings now protect us and keep us comfortable while saving energy and cutting emissions. These types of smart buildings play a vital role in building smart cities of the future. The aim of this study is to help facility managers predict the thermal sensation of the occupants under the given circumstances. To achieve this, we applied a data-driven approach to predict the thermal sensation of occupants of an indoor environment using previously collected data. Our main contribution is to design and evaluate a deep neural network (DNN) for predicting thermal sensations with a high degree of accuracy regardless of building type, climate zone, or a building’s heating and/or ventilation method. We used the second version of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Global Thermal Comfort Database to train our model. The hyperparameter-tuning process of the proposed model is optimized using the Bayesian strategy and predicts the thermal sensation of occupants with 78% accuracy, which is much higher than the traditional predicted mean vote (PMV) model and the other shallow and deep networks compared.
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In addition to typical indoor and outdoor spaces, there are numerous transitional spaces in a building that are unlike indoor and outdoor spaces, where most people spend time for entertainment. There is a need to investigate the comparison between these three types of spaces, including indoor spaces, transitional spaces and outdoor spaces. In this study, the thermal responses and thermal environmental parameters of the indoor, outdoor and transitional spaces were simultaneously recorded. Values of standard effective temperature (SET*), physiologically equivalent temperature (PET) and universal thermal climate index (UTCI) were calculated, and relationships between mean thermal sensation vote (MTSV), SET*, PET and UTCI were also analysed. The results indicate that the air velocity fluctuation and mean radiant temperature of the outdoor space were more significant than those of other two spaces. The neutral thermal indices of the outdoor space were higher than those of the indoor and transitional spaces. Additionally, regression models between MTSV and thermal indices (SET*, PET and UTCI) were analysed. There are strong linear relationships between MTSV and SET* in all spaces. The linear relationships between MTSV were significant when compared with PET and UTCI. Thus, the adaption of thermal indices for evaluation of different spaces must be considered.
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Extreme thermal environments harm the health and reduce the productivity of outdoor workers. Variations in human physiological indices and the thermal exposure time limit are the main factors in evaluating heat safety in an extreme thermal environment. Therefore, it is necessary to determine the relationships between human physiological indices, psychological responses, and thermal parameters to accurately predict and evaluate human thermal safety in extreme thermal environments. A field survey, including thermal parameter measurements, was conducted at construction sites in South China during the summer of 2019. The relationship between health risk and thermal parameters was obtained, and the adaptability and sensitivity of workers to i) thermal parameters (outdoor ambient temperature (Ta), mean radiant temperature (Tmrt), wind speed (Va), and relative humidity (RH)) and ii) physiological indicators (heart rate (HR) and auditory canal temperature (ACT)), as well as the variations in their cognitive ability, were analyzed. The results indicate that 40% of workers experienced discomfort and that when Ta > 34 °C, the working intensity of workers needs to be reduced in construction sites. The HR and ACT increased with increasing working hours, and the thermal parameters and cognitive ability decreased. To avoid discomfort, it is suggested that the HR may be kept near 94 beats/min. The effects of physiological indicators and cognitive ability on the physical and mental state of the workers were significant; with an increase in thermal environment parameters, the efficiency decreased by approximately 8%. The results of this investigation are beneficial for ensuring the occupational safety of workers and reducing the risk of heat exposure.
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The set-point temperature of room air conditioners (RACs) is extremely critical for cooling energy consumption of residential buildings. However, current research on temperature-setting behavior is limited owing to the limitations of data acquisition. This study aims to identify the typical temperature-setting patterns for RACs and explore the association of temperature-setting behavior with other RAC operation characteristics. The data obtained from the big data cloud platform of an RAC manufacturer were analyzed in this study. These data consist of measured data from 966 bedroom RACs (BRACs) and 321 living room RACs (LRACs). First, the RAC operation characteristics, involving five aspects, namely, set-point temperature, set wind speed, indoor temperature, operation duration, and energy consumption, were extracted from the raw data by transforming, aggregating, and merging the bottom-level measured data. Subsequently, cluster analysis was performed to identify various and typical temperature-setting behavior patterns. Five typical temperature-setting patterns for BRACs and six typical patterns for LRACs were obtained. Afterwards, data mining methods of difference analysis and association analysis were employed to explore the differences and association, respectively, of different temperature-setting patterns with other operation characteristics of RACs (e.g., set wind speed, indoor air temperature, operation duration, and energy consumption). The results of this study can provide researchers with references of temperature-setting strategies in residential building energy simulation and quantify the energy impacts of diverse temperature-setting patterns in residential buildings.
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A carefully chosen indoor comfort temperature as the thermostat set-point is the key to optimizing building energy use and occupants’ comfort and well-being. ASHRAE Standard 55 or ISO Standard 7730 uses the PMV-PPD model or the adaptive comfort model that is based on small-sized or outdated sample data, which raises questions on whether and how ranges of occupant thermal comfort temperature should be revised using more recent larger-sized dataset. In this paper, a Bayesian inference approach has been used to derive new occupant comfort temperature ranges for U.S. office buildings using the ASHRAE Global Thermal Comfort Database. Bayesian inference can express uncertainty and incorporate prior knowledge. The comfort temperatures were found to be higher and less variable at cooling mode than at heating mode, and with significant overlapped variation ranges between the two modes. The comfort operative temperature of occupants varies between 21.9 and 25.4°C for the cooling mode with a median of 23.7°C, and between 20.5 and 24.9°C for the heating mode with a median of 22.7°C. These comfort temperature ranges are similar to the current ASHRAE standard 55 in the heating mode but 2-3°C lower in the cooling mode. The results of this study could be adopted as more realistic thermostat set-points in building design, operation, control optimization, energy performance analysis, and policymaking.
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Climate is one of the most important factors affecting human thermal comfort. In this study, we explore the influence of regional climate on thermal comfort by considering our data (collected in recent years) with those currently available in the scientific literature. By combining them, we obtained the regional and seasonal database of thermal comfort in China. The regional and seasonal distribution characteristics of indoor/outdoor air temperatures and of human thermal responses have been compared, establishing some relationships. In winter, the thermal environment and human thermal responses between northern and southern China were statistically different; however, they were not statistically different in summer. The seasonal differences in thermal environment and human thermal responses in each region were statistically significant. In neutral thermal environments, the neutral temperature was always close to the indoor mean temperature. In warmer (colder) environments, although the neutral temperature of the subjects was higher (or lower) than the indoor mean temperature, people could always accept their surroundings if provided with available adaptation opportunities. Overall, these findings support the climate adaptation theory and can serve as reference for the design of low-energy buildings.
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Purpose The purpose of this paper is to examine the seasonal performance, occupants’ comfort and cold stress in cross-laminated timber school buildings located in the USA (Northeast region). Design/methodology/approach The Fall survey was done from October–November 2017. In the Winter, it was considered from December 2017–February 2018. The study measured environmental parameters in the chosen spaces. The research applied the wet-bulb globe temperature (WBGT) model to determine the indexes in various seasons. Findings In the Fall, the average inside temperature was 21.2°C, the average RH was 50.7 per cent, and the mean dew-point was 9.3°C. The mean inside temperature was 20.5°C in the Winter while the mean RH was 23.9 per cent and the average dew-point was −1.9°C. The overall mean inside temperatures in both seasons were within the ASHRAE comfort temperature limits for cold seasons. During the surveys, higher average values of temperature, RH and dew-point were measured in the offices than the other spaces. Practical implications The research showed people might be subject to lower temperatures in the hall than the other spaces. Some design parameters and occupation hours may contribute to the lower temperatures reported in the hall than the different spaces. Originality/value The study proposes the WBGT of 16.0°C and 13.7°C as the stress indexes in the Fall and Winter seasons correspondingly. Last, the research suggests a WBGT of 14.9°C as the overall mean stress index within the spaces considered in this study.
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The study examines stress indices and occupants’ comfort in a cross-laminated timber school building in the Northeast US in different seasons. The case study has won different awards for its sustainability credentials and use of structural timber for the construction. The environmental parameters were measured in the cold and warm periods. Thermal comfort models were applied to evaluate the occupants’ comfort. The stress indices were computed using the Wet-Bulb Globe Temperature and Universal Thermal Climate Index (UTCI) models. The average internal temperatures of 20.2°C and 22.5°C were measured in the cold and warm periods. In the cold and warm seasons, the mean relative humidity values were 43.6% and 58.3%, respectively. Lower and higher temperatures were noted during the occupied and non-occupied hours, which can cause warm and cold discomfort. The proposed Wet-Bulb Globe Temperature and UTCI in the warm period are 3.4°C and 3.0°C higher than the values computed for the cold season. The overall results showed that no thermal stress is predicted in the spaces. The study recommends that designers should consider thorough assessments before recommending interventions in buildings. The study also suggests that occupants should be enabled to adjust the thermal environment of buildings outside the occupied hours.
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Thermal environment is important for both occupants’ comfort and health. Previously, the impacts of thermal environment were explored in the areas of thermal comfort and public health separately. This paper aims to bridge both disciplines by examining the correlation between comfort temperature and Minimum Mortality Temperature (MMT), which is a key index quantifying the association of health and weather temperature, through literature review and data-driven approach. It was found that the MMT data obtained from the public health area are generally in good agreement with the thermal neutral temperatures from the comfort perspective. The MMT data range from 17.2 °C to 30 °C, which are similar to the thermal neutral temperatures ranging from 19.5 °C to 30 °C based on the global field tests. Moreover, the MMT data demonstrate the potential to capture some complex distribution patterns of the field comfort data. The introduction of the health-temperature data could assist the intensive field experiments and modeling efforts and complement the thermal comfort dataset, which suffers from the problems of limited sample size. Some discrepancies between the two datasets were identified as well. The contextual factors other than the climate factor which may cause such discrepancies, such as socio-economics, population densities, etc. should be analyzed to enable the potential application of the health-temperature data and modeling to thermal comfort and health studies.
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Air conditioning has been basically generalized in buildings as the most effective means of cooling in South China; there are two common types of air conditioning: centralized air conditioning system and split-type air-conditioner. The present study recruited 60 healthy young people, half from buildings with centralized air conditioning system (CAC buildings) and half from buildings with split-type air-conditioner (SAC buildings), and exposed them to a wide range of temperatures (20–32 °C) and humidity (50% and 70%) in a climate chamber. The results showed that the mean skin temperature was significantly higher for subjects from the CAC buildings under the non-neutral conditions, whereas there were no significant differences for other physiological responses. The two groups of subjects reported the same neutral temperatures (26.8 °C and 26.6 °C) and thermal sensitivities (0.31 °C⁻¹). The 90% thermally acceptable SET ranges were 24.8–27.4 °C and 24.4–30.1 °C for the two groups of subjects, and the range was narrower by 3.1 °C and the upper limit was lower by 2.7 °C for subjects from the CAC buildings. Thermal history containing intermittent and short-term high & low-temperature exposures in the SAC buildings is suggested to strengthen the occupants' thermoregulatory ability. The long-term experience with a more stable cool environment and the less perceived controls are expected to shape a higher thermal expectation of occupants in the CAC buildings. This study specifies the thermal requirements of people in the two types of air-conditioned buildings, and promotes the understanding of the impacts of thermal history and expectation on human thermal comfort.
Chapter
In the world’s hot and humid regions, economic development has recently resulted from both the utilization of these regions’ natural resources, from oil to metallic minerals. This economic growth has resulted in a widespread demand for better thermal comfort and indoor environmental quality in houses and buildings. There are several technologies available that can be applied to buildings in hot and humid regions to maintain indoor thermal comfort and air quality. Such technologies can be either passive or active. Common passive technologies include natural ventilation, evaporative cooling, and ground cooling. Widely used active technologies include the utilization of different heat pump technologies with different working materials. With rapid urbanization and increasing awareness of energy conservation and the environment, some new technologies have combined both active and passive technologies to promote the use of clean energy sources and technologies in hot and humid regions.
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This paper focuses on thermal environmental conditions in the stone dwellings of a Tibetan village in Danba County, Sichuan, China, in winter. During the study, field measurements and subjective survey studies were collected, simultaneously, to provide a comprehensive understanding of the thermal comfort conditions that were experienced by residents in cold rural areas of Sichuan. Subjective surveys involved questions about thermal comfort perceptions and acceptability in cold conditions. The status of thermal comfort and characteristics of indoor environmental qualities were investigated in the study. The majority of survey participants (47% and 74%) voted as “slightly cool” for temperature, and “slightly dry” for humidity in the studied typical winter days, respectively. The available adaptive opportunities for the residents were investigated through the survey studies. Adjusting clothing, drinking hot beverages, blocking air infiltration through windows, and changing activities were the most common adaptive measures. An adaptive coefficient ( λ ) was determined based on adaptive predicted mean votes (aPMV) models using least square methods to assess the different adaptation measures in the region. Findings of this study provided a valuable reference for thermal comfort adaptations in cold climates, where limited adaptive opportunities were available due to the low standard of living.
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With the development of the urban city, increasing attention has been paid to outdoor thermal comfort. In this paper, an analysis of the sensitivities of different factors, including the personal factors and physical parameters of the thermal environment was conducted. The results showed that there was a strong linear relationship between the Physiological Equivalent Temperature (PET) and operation temperature. When the operation temperature was lower than 32 °C, the effect of air velocity on the PET was positive. However, the effects of other factors, including relative humidity, clothing insulation, and metabolic rate, on the PET were insignificant. An exponential relationship was found between the UTCI and the operation temperature. The effect of air velocity change on the UTCI became weaker and weaker with the increase of operation temperature. Compared with the PET, the linear relationship between the UTCI and relative humidity was clearer. A field survey of thermal comfort carried out in Guangzhou University was used for the validation of the thermal comfort models. It was observed that the clothing insulation requirement increased with the decrease of air temperature in autumn. The variations in metabolic rate were also obvious, from 1met to 3.8 met. More than 70% of the people had been walking before they arrived at the survey locations. In addition, there were some differences in the neutral PET and UTCI temperature between the metabolic rates of 1.0–2.0 met and of 2.6 met. Meanwhile, models of MTSV against the PET and UTCI under different metabolic rates were established.
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Past research (ASHRAE RP-884) demonstrated that occupants of naturally ventilated buildings are comfortable in a wider range of temperatures than occupants of buildings with centrally controlled HVAC systems. However, the exact influence of personal control in explaining these differences could only be hypothesized because of the limits of the existing field study data that formed the basis of that research. The objective of ASHRAE RP-1161 was to quantitatively investigate how personal control of operable windows in office settings influences local thermal conditions and occupant comfort. We conducted a field study in a naturally ventilated building where occupants had varying degrees of control over the windows. Utilizing continuous measurement of each subject's workstation microclimate, plus a Web-based survey that subjects took several times a day and was cross-linked to concurrent physical assessments of workstation microclimatic conditions, we collected over 1000 survey responses in each of the two main seasons. The data show that occupants with different degrees of personal control had significantly diverse thermal responses, even when they experienced the same thermal environments and clothing and activity levels. Our findings offer further empirical support for the role of shifting expectations in the adaptive model of thermal comfort.
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This paper presents the results of surveys of the use of simple controls - opening of windows, the closing of window blinds, and the use of lighting, heaters, and fans - by building occupants. Information is also presented on the use of air conditioning in mixed-mode buildings. The surveys were conducted in the UK, Pakistan, and throughout Europe. The data are analyzed to show how the use of each control varies with outdoor temperature. The paper discusses the application of such results to the simulation of occupied buildings.
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Adaptive thermal comfort criteria for building occupants are now becoming established. In this paper we illustrate their use in the prediction of occupant behaviour and make a comparison with a non-adaptive temperature threshold approach. A thermal comfort driven adaptive behavioural model for window opening is described and its use within dynamic simulation illustrated for a number of building types. Further development of the adaptive behavioural model is suggested including use of windows, doors, ceiling fans, night cooling, air conditioning and heating, also the setting of opportunities and constraints appropriate to a particular situation. The integration in dynamic simulation of the thermal adaptive behaviours together with non-thermally driven behaviours such as occupancy, lights and blind use is proposed in order to create a more complete model of occupant behaviour. It is further proposed that this behavioural model is implemented in a methodology that includes other uncertainties (e.g. in internal gains) so that a realistic range of occupant behaviours is represented at the design stage to assist in the design of robust, comfortable and low energy buildings.
Technical Report
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The adaptive hypothesis predicts that contextual factors and past thermal history modify building occupants' thermal expectations and preferences. One of the predictions of the adaptive hypothesis is that people in warm climate zones prefer warmer indoor temperatures than people living in cold climate zones. This is contrary to the static assumptions underlying the current ASHRAE comfort standard 55-92. To examine the adaptive hypothesis and its implications for Standard 55-92, the ASHRAE RP-884 project assembled a quality-controlled database from thermal comfort field experiments worldwide (circa 21,000 observations from 160 buildings). Our statistical analysis examined the semantics of thermal comfort in terms of thermal sensation, acceptability, and preference, as a function of both indoor and outdoor temperature. Optimum indoor temperatures tracked both prevailing indoor and outdoor temperatures, as predicted by the adaptive hypothesis. The static predicted mean vote (PMV) model was shown to be partially adaptive by accounting for behavioral adjustments, and fully explained adaptation occurring in HVAC buildings. Occupants in naturally ventilated buildings were tolerant of a significantly wider range of temperatures, explained by a combination of both behavioral adjustment and psychological adaptation. These results formed the basis of a proposal for a variable indoor temperature standard.
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The origin and development of the adaptive approach to thermal comfort is explained. A number of recent developments in the application of the theory are considered and the origin of the differences between adaptive thermal comfort and the ‘rational’ indices is explored. The application of the adaptive approach to thermal comfort standards is considered and recommendations made as to the best comfort temperature, the range of comfortable environments and the maximum rate of change of indoor temperature. The application of criteria of sustainability to thermal standards for buildings is also considered.
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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.
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Thesis (M.S. in Architecture)--University of California, Berkeley, Spring 2004. Includes bibliographical references (leaves 99-101).
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This paper presents the results of the ASHRAE methodology for thermal comfort study applied in Taiwan. Field experiments conducted in 10 naturally ventilated and 26 air-conditioned campus classrooms used survey questionnaires and physical measurements to collect data. A total of 944 individuals in seven universities completed 1294 questionnaires. The chi-square tests were applied to find the significant aspects that affect students’ thermal sensations. The results show that air temperature, air movement and mean radiant temperature have significant influence, but humidity has no statistical significance. By using probit regressive analyses, the thermal neutrality and thermal preference of students occurred at 26.3°C ET* and 24.7°C ET*, respectively. Responses from those students suggest a wider acceptable temperature range for occupants in Taiwan. The margins of the acceptable zones obtained from direct and indirect acceptability assessing methods are 21.1–29.8°C ET* and 24.2–29.3°C ET*, respectively. When compared with similar studies elsewhere, this finding supports the sentiments on climatic adaptation.
Article
This study was conducted during the summer and winter in Beijing. Classrooms and offices in a university were used to conduct the survey. The respondents’ thermal sensation and thermal adaptability in both seasons were analyzed. During the study, indoor environmental parameters including air temperature, mean radiant temperature, relative humidity, and air velocity were measured. The respondents’ thermal sensation was determined by questionnaire.A relationship between indoor temperature and thermal sensation was found. In the summer study, the “scissors difference” between TSV and PMV was observed in the air-conditioned environments if the temperature was out of the neutral zone. People had higher tolerance in the hot environment than PMV predicted. During winter, the outdoor temperature had a prominent influence on thermal adaptability. The low outdoor temperature made people adapt to the cold environment. When the indoor temperature was heated to a high temperature by space heating facilities, respondents felt uncomfortable since their adaptability to the cold environment was nullified.Furthermore, the differences in thermal responses between respondents from North and South China showed that the different climates of people's native regions also affected their thermal comfort and adaptability.
Article
A field study was conducted in classrooms in Singapore, which were mechanically ventilated by fans, to assess their thermal conditions during the students’ lesson hours. Thermal comfort variables were measured at the same time when students and teachers answered a survey on their perception/sensation of the indoor climate. Objective data analysis showed that none of the classes had thermal conditions falling within the comfort zone of ASHRAE standard 55. Occupants found temperature range beyond the comfort zone acceptable. This suggests that the standard is not applicable in free-running buildings in the local climate. A new PMV model, which incorporates two common forms of adaptation-reducing activity pace and expectation, still showed discrepancy in predicting actual thermal sensations, especially at lower temperatures. Comparison of the various methods of assessing thermal acceptability showed that they produce widely disparate results, with the Bedford scale giving the highest level of acceptability. Classroom occupants generally accepted cool thermal sensations more readily than warm thermal sensations.
Article
The relationship between thermal sensation and thermal comfort was studied experimentally under uniform and non-uniform, steady and dynamic conditions separately. Thirty subjects participated in all the experiment and reported their thermal sensation and thermal comfort simultaneously. Thermal sensation and comfort are found to be correlated closely under steady and uniform conditions and the comfort zone of thermal sensation vote in warm side is (0, 1.25). Under steady and non-uniform conditions thermal sensation change with space is found to be an important factor determining thermal comfort. Combining the effects of overall thermal sensation and thermal sensation change with space, a thermal comfort model for steady conditions is proposed. Under dynamic conditions, thermal sensation change with time affects thermal comfort significantly.
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Research into thermal comfort and sensation has been largely conducted in climate chambers, since such laboratory experimentation allows independent control of the physical and personal variables. The work has provided a sound understanding of the quantitative relation between the variables and average thermal sensation of a group of people. However, this essentially reductionist approach disregards some important but ill-understood factors affecting comfort. This paper addices field evidence to point out some discrepancies between laboratory predictions and actual comfort responses. Some of these discrepancies may be explained by a seasonal distortion of the rating scales in common use. Present emphasis on energy conservation demands an understanding of acceptable levels of discomfort, and it is shown how available methods of measuring discomfort and acceptability are inadequate.
Article
Repeated surveys of occupant control of the indoor environment were carried out in Danish dwellings from September to October 2006 and again from February to March 2007. The summer survey comprised 933 respondents and the winter survey 636 respondents. The surveys were carried out by sending out invitations to addresses obtained from a Danish register along with information on dwelling characteristics. Meteorological data was obtained from the Danish Meteorological Institute.Four control mechanisms (window open/closed, heating on/off, lighting on/off and solar shading in/not in use) were analysed separately by means of multiple logistic regression in order to quantify factors influencing occupants’ behaviour.The window opening behaviour was strongly related to the outdoor temperature. The perception of the environment and factors concerning the dwelling also impacted the window opening behaviour.The proportion of dwellings with the heating turned on was strongly related to the outdoor temperature and the presence of a wood burning stove. The solar radiation, dwelling ownership conditions and the perception of the indoor environment also affected the use of heating.The results of the statistical analyses form a basis for a definition of standard behaviour patterns which can be used to make calculation of energy consumption of buildings more accurate.
Article
A field study of the thermal comfort of workers in natural ventilated office buildings in Oxford and Aberdeen, UK, was carried out which included information about use of building controls. The data were analysed to explore that what effect the outdoor temperature has on the indoor temperature and how this is affected by occupants’ use of environmental controls during the peak summer (June–August). The proportion of subjects using a control was related to indoor and outdoor temperatures to demonstrate the size of the effect. The results suggest that the use of controls is also related to thermal sensation and their appropriate use is a significant part of adaptive behaviour to modify the indoor thermal conditions. The results make it possible to predict the effect of temperature on the ventilation rate in naturally ventilated buildings.
Article
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).
Article
A field study of thermal comfort was conducted in Bangkok, Thailand, in which over 1100 office workers responded to a questionnaire while simultaneous physical measurements were taken. In this study we explore whether there is justification for adopting a comfort standard that differs from those developed for office workers accustomed to more temperate climates. Both air-conditioned and naturally ventilated offices were surveyed. Participants cast votes on standard subjective thermal rating scales and these were correlated with temperature indices that variously account for the thermal impacts of humidity, radiant temperature, air velocity, and clothing levels. Following the criteria used in developing a widely adopted thermal comfort standard, it was found that the upper temperature bound for a Thai comfort standard, instead of being the currently accepted level of 26.1 °C for those accustomed to air-conditioning accustomed to naturally ventilated spaces, and as high as 28 °C for those accustomed to air-conditioning. Comparing the responses from the naturally ventilated buildings with both those from the air-conditioned buildings and from studies conducted in the temperate regions provides convincing evidence of acclimatization. These and other findings of this study suggest that interior spaces in Thailand can be cooled to a far lesser degree without sacrificing comfort.
Article
This paper presents the results of an extensive literature review on the topic of thermal adaptation in the built environment. The adaptive approach to modeling thermal comfort acknowledges that thermal perception in ‘real world’ settings is influenced by the complexities of past thermal history and cultural and technical practices. An important premise of the adaptive model is that the person is no longer a passive recipient of the given thermal environment, but instead is an active agent interacting with the person—environment system via multiple feedback loops. Thermal adaptation can be attributed to three different processes—behavioral adjustment, physiological acclimatization and psychological habituation or expectation. Both climate chamber and field evidence indicates that the slower process of acclimatization is not so relevant to thermal adaptation in the relatively moderate conditions found in buildings, whereas behavioral adjustment and expectation have a much greater influence. One of the most important findings from our review of field evidence was the distinction between thermal comfort responses in air-conditioned vs. naturally ventilated buildings, most likely resulting from a combination of past thermal history in the buildings and differences in levels of perceived control.
Article
The relationships between overall thermal sensation, acceptability and comfort were studied experimentally under uniform and non-uniform conditions separately. Thirty subjects participated in the experiment and reported their local thermal sensation of each body part, overall thermal sensation, acceptability and comfort simultaneously. Sensation, acceptability and comfort were found to be correlated closely under uniform conditions and acceptable range ran from neutral to 1.5 (midpoint between ‘Slightly Warm’ and ‘Warm’) on thermal sensation scale and contained all comfortable and slightly uncomfortable votes on thermal comfort scale. Under non-uniform conditions overall thermal acceptability and comfort were correlated closely. However, overall thermal sensation was apart from the other two responses and non-uniformity of thermal sensation was found to be the reason for the breakage. Combining the effects of overall thermal sensation and non-uniformity of thermal sensation, a new thermal acceptability model was proposed and the model was testified to be applicable to uniform and non-uniform conditions over a wide range of whole body thermal state from neutral to warm.
Article
A field study on thermal comfort and building energy has been carried out in Jakarta—the capital city of Indonesia. Some 596 office workers working in seven multi-storey office buildings participated in this study. This paper examines the neutral temperature of the whole sample, and also examines the neutral temperatures of the sub group sample, such as male and female subjects, subjects under and over 40 years of age, subjects who are considered to be thin, normal and fat, subjects with various ethnic backgrounds, etc. This study also reveals that comfort conditions could be achieved without unnecessary cooling in air conditioned buildings.
Article
For naturally ventilated buildings (NVB) located in the tropical regions, thermal comfort (TC) prediction based on predicted mean vote (PMV) standard has shown some deviations from the observed results. Hot and humid environmental conditions throughout the year and personal adaptation could have an effect on expectation and perception about TC. Through an extensive field survey conducted in residential buildings in Indonesia, 525 sets of data had been gathered. The data analysis revealed that the PMV equation had predicted warmer thermal perception as compared to what people actually felt. Interestingly, it was observed that under hot and humid tropical climate, people indicated preference to cooler environment as compared to what the neutral temperature has shown. The study also investigated the occupant’s adaptive control preferences in creating a more thermally comfortable living environment. The reciprocal effects of occupant’s thermal perception and behavioural adaptation were explored. In tropical free-running buildings where the air temperature and humidity might not be modified easily without mechanical means, the people seemed to prefer higher wind speed.
Article
The indoor thermal climate is an important issue affecting the health and productivity of users in buildings. In designing of air-conditioning systems, it is believed that the conventional fixed temperature setpoint concept is not appropriates, the indoor comfort temperature depends on the outdoor air temperature and the business culture, such as the nature of activities, dress of occupants, etc. Researchers have been interested in investigating adaptive temperature control for a realistic in situ temperature control for comfort. Unfortunately, these studies put great emphasis on the energy saving opportunity, rather than providing an integrated solution. In this paper, we report the findings of a large-scale survey that was performed to develop new notions about adaptive comfort temperature (ACT) in buildings in humid sub-tropical Hong Kong, and determine the adaptive interface relationship of indoor comfort temperature with outdoor air temperature in order to preset the indoor air temperature as a function of outdoor air temperature. This ACT algorithm is intended to optimise the energy used for cooling that air, but achieve the acceptance of thermal comfort, as determined by physical measurements and subjective surveys. With the integration of the ACT model, the total percentage of energy saving is about 7%.
Article
Numerous studies are in progress to support adaptive models in indoor thermal comfort evaluation and to establish quantitative indexes to allow the subject to optimize his/her comfort conditions.A wide experimental campaign was carried out in moderate environments, such as university classrooms, and a multiple choice questionnaire was elaborated, comprehensive of information for the static and adaptive model proposed by UNI EN ISO 10551, in order to find a correlation between experimental data measured by the instruments and subjective responses given by the occupants. The questionnaire was applied in autumn, winter and spring in classrooms of the University of Perugia, Terni and Pavia. During the campaign, all data needed to calculate both Fanger and Wray comfort indices were acquired by instrumental surveys and questionnaire compilation. By means of results' analysis of both questionnaires and measurements, the following couple of parameters (derived from Fanger and Wray) were correlated: Predicted Mean Vote (PMV) versus the difference between the Equivalent Uniform Temperature and the Comfort Uniform Temperature (Teu − Tu) and the Predicted Percentage of Dissatisfied (PPD) versus the absolute value of the same difference between temperatures (|Teu − Tu|). For the first couple of parameters, a linear correlation was found while for the second one a second-degree polynomial relation was obtained. Better correlation was found for measurement data rather than questionnaire results. Finally values of Operative Temperature T0 and Equivalent Uniform Temperature Teu, obtained for each single experimental survey, were compared, observing a very good agreement between the two quantities, with differences that exceed 0.1 K only for a few number of values. Questionnaire and experimental PMV data were also correlated to T0: higher values of questionnaire than instrumental PMV were obtained for the same value of T0.
Article
This paper describes two field studies of thermal comfort conducted in Ilam, a city located in western Iran. The first study consisted of two short-term surveys carried out during two climatically extreme periods—a hot summer and a cold winter—in 1998. The second study consisted of a long-term survey that collected data throughout the whole of 1999. Both studies were performed in naturally ventilated buildings. This paper shows some comparative analysis between the findings from the short-and long-term studies. For the hot season the neutral temperatures from the short-and long-term studies were 28.4 and 26.7 °C, respectively. For the cold season the short-and long-term neutral temperatures were 20.8 and 21.2 °C, respectively. The results show a very good agreement between both studies in Iran. The main points of interest from the studies were the variability of acceptable conditions, a good relationship between neutral temperature and room temperatures and also, more importantly, between indoor comfort and outdoor conditions. The findings reveal that the people in the study could achieve comfort at higher indoor air temperatures compared with the recommendations of international standards such as ISO 7730.
Article
Based on almost seven years of continuous measurements, we have analysed in detail the influence of occupancy patterns, indoor temperature and outdoor climate parameters (temperature, wind speed and direction, relative humidity and rainfall) on window opening and closing behaviour. In this we have also considered the variability of behaviours between individuals. This paper begins by presenting some of the key findings from these analyses. We go on to develop and test several modelling approaches, including logistic probability distributions, Markov chains and continuous-time random processes. Based on detailed statistical analysis and cross-validation of each variant, we propose a hybrid of these techniques which models stochastic usage behaviour in a comprehensive and efficient way. We conclude by describing an algorithm for implementing this model in dynamic building simulation tools.
Article
Human responses to thermal environments in naturally ventilated (NV) buildings in hot-humid area of China were systematically investigated in the present study. Thirty local inhabitants long-time living in NV buildings participated in the study and reported their thermal sensations and perceptions and adaptive behaviors while all physical and personal variables were collected. Based on a year-long survey, a close match of indoor physical variables and occupants’ clothing insulation with outdoor climate was found as an important feature of NV buildings. Integrated indices can capture more thermal contexts in the NV buildings in hot-humid area of China than simple indices. Thermal sensation was found to be a good linear function of SET* with the thermal neutrality of 25.4 °C and the 90% (80%) acceptable range of 23.5–27.4 °C (22.1–28.7 °C) in SET*. The adaptive evidences were obtained for clothing adjustment, window opening and using fan respectively and the modified PMV model was validated to be applicable in NV buildings in hot-humid area of China with an expectancy factor of 0.822. Comparisons with other field studies indicate that people can develop various human-environment relationships through thermal adaptation to local climate, resulting in different thermal neutral temperatures in various climates. The subjects in hot-humid area of China are more acclimated and tolerable with hot and humid environments and more uncomfortable and intolerable with cold environments while compared with those in temperate climates.
Article
Sensory estimates of comfort and thermal sensation for resting-sitting unclothed subjects have been compared with the associated physiological responses for the range of ambient temperatures (12°–48°C) under steady-state and transient conditions. For steady exposure to cold and warm environments, thermal comfort and neutral temperature sensations lie in the range for physiological thermal neutrality (28°–30°C), in which there is no physiological temperature regulatory effort. Discomfort increases more rapidly below 28°C than above 30°C, while thermal sensation for both heat and cold increases rapidly each side of neutral. Discomfort correlates best with lowering average skin temperature toward cold environments and with increased sweating toward hot environments. In general, discomfort is associated with a change of average body temperature from 36.5°C. The same conclusion follows for transient changes when the subject goes from comfortable to uncomfortable, neutral to cold, and neutral to warm. When these transients are reversed (i.e., cold to neutral, hot to neutral), the sensations of comfort and temperature “lead” the body temperature changes and are thus “anticipatory.” This hysteresis effect is most striking in the cold and less so for warmth. For transients from cold to warm, the rate of rise of skin temperature causes a sensation that compensates for and predominates over the sensation of discomfort caused by a low skin temperature itself. Finally, thermal discomfort is an excellent stimulus for behavioral activity by man. As a sensation, it gives man both an early and anticipatory drive for conscious action that may effect changes in his body's microclimate rather than having him depend on natural but short-term means of thermal protection—sweating, vasodilation, vasoconstriction and shivering.
Meteorological data for built environmental analysis in China
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