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The effect of air-conditioning on worker productivity in office buildings: A case study in Thailand
Abstract
This paper presents findings from a study of the impact of indoor thermal conditions on the productivity of office workers
in Thailand. The experiment simulating office working conditions was carried out with a completely randomized design under
a variety of indoor thermal conditions over different time periods. In the experiment, subjects performed five simulated tasks:
calculation, typing, proof-reading, simple quick reaction, and concentration-needed reaction. Normalized changes in worker
productivity associated with those five tasks were measured and analyzed using the analysis of variance technique. In this
study, the ranges of thermal conditions resulting in the greatest productivity were calculated by the predicted mean votes
(PMVs). The results of this study suggest that the general appropriate PMV value recommended by ISO 7730 is suitable for Thais
only in afternoon and evening periods. In addition, it was found that a satisfactory thermal comfort condition for office
workers can be achieved by setting the temperatures of air-conditioning systems at 26 °C–28 °C for morning periods and at
24.5 °C–26 °C for afternoon and evening periods. These ranges of temperature settings help maintain and improve the productivity
of office workers during morning, afternoon, and evening periods by 18%, 1% to 15%, and 7%, respectively.
Keywordsproductivity-thermal condition-predicted mean vote (PMV)-office work simulation-energy conservation-design of experiment
... Performance/Productivity Assessment [7,14,40,[62][63][64][65][66][67][68][69][70][71][72] Subjective assessment. [38,43,[73][74][75] Physiological/subjective assessment. ...
... [62] Thermal comfort. [63] Air temperature, air velocity, relative humidity and time of day. [84] Global temperature compared to air temperature. ...
... A condition for satisfactory thermal comfort for office employees can be reached with temperatures from air-conditioning systems at 26-28 °C in the mornings and at 24-26 °C in the afternoon and at night. These temperature setting ranges help to maintain and improve employees' productivity in the office in the morning periods (18%), afternoon (1% to 15%) and evening (7%) (Ngarmpornprasert and Koetsinchai, 2010) [63]. According to Kekäläinen et al. (2010) [69], the percentage of dissatisfied people and neural behavioural systems with air quality increased and self-estimation on work efficiency decreased considerably with temperatures above 25 °C. ...
The thermal environment is one of the main factors that influence thermal comfort and, consequently, the productivity of occupants inside buildings. Throughout the years, research has described the connection between thermal comfort and productivity. Mathematical models have been established in the attempt to predict changes in productivity according to thermal variations in the environment. Some of these models have failed for a number of reasons, including the understanding of the effect that several environment variables have had on performance. From this context, a systematic literature review was carried out with the aim of verifying the connection between thermal comfort and productivity and the combinations of different thermal and personal factors that can have an effect on productivity. A hundred and twenty-eight articles were found which show a connection between productivity and some thermal comfort variables. By means of specific inclusion and exclusion criteria, 60 articles were selected for a final analysis. The main conclusions found in this study were: (i) the vast majority of research uses subjective measures and/or a combination of methods to evaluate productivity; (ii) performance/productivity can be attained within an ampler temperature range; (iii) few studies present ways of calculating productivity.
... Of the 59 cities (in 12 countries) with the greatest potential for growth in air conditioning use by the end of the century, during peak conditions, fan use would have been beneficial in 40 (67·8%) cities for young healthy adults, 30 (50·8%) for healthy older adults, and 19 (32·2%) for older adults taking anticholinergic medication; for the 95th percentile conditions, fan use would have been beneficial in 58 (98·3%) cities for young healthy adults, 54 (91·5%) for healthy older adults, and 53 (89·8%) for older adults taking anticholinergic medication. The lowest temperature below which fan use would never have been detrimental across all levels of relative humidity, for each city and by continents is in the appendix (pp [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Globally, the temperatures below which fan use would always be beneficial irrespective of humidity levels present were 39·0°C for young healthy adults, 38·0°C for heathy older adults, and 37·0°C for older adults taking anticholinergic medication. ...
... 6 Most of these countries are tropical and, as such, heat stress conditions are predominantly characterised as hot and humid; the conditions wherein clinical trials have demonstrated fan use to be effective for cooling in young healthy adults. 17 At present, many of these countries do not have the infrastructure to support the electricity required to operate the increasing number of air conditioning units, and therefore are at high risk of power disruptions that disturb economic output 26 and threaten the capacity of health-care systems as a result of further surges in heat-related mortality and morbidity. 9 One of the most common public health concerns regarding electric fan use during heatwaves is the potential acceleration of dehydration. ...
Background
In hot weather, electric fans can potentially provide effective cooling for people, with lower greenhouse gas emissions and cost than air conditioning. However, international public health organisations regularly discourage fan use in temperatures higher than 35°C, despite little evidence. We aimed to determine humidity-dependent temperature thresholds at which electric fans would become detrimental in different age groups.
Methods
We used biophysical modelling to determine the upper humidity-dependent temperature thresholds at which fan use would become detrimental (ie, worsen heat stress) for healthy young adults (aged 18–40 years), healthy older adults (aged ≥65 years), and older adults taking anticholinergic medication. We also obtained hourly environmental data for the period Jan 1, 2007, to Dec 31, 2019, for 108 populous cities to determine the number of days fan use would be effective for cooling, standardised to a 31-day hot weather month. We established simplified temperature thresholds for future fan use recommendations on the basis of temperatures below which fan use would never have been detrimental between Jan 1, 2007, and Dec 31, 2019, across all prevailing levels of ambient humidity.
Findings
According to our model, fan use would have been beneficial on 30·0 (96·6%) of 31 hot weather days for healthy young adults and 29·4 (94·9%) of 31 hot weather days for both older adults and older adults taking anticholinergic medication between Jan 1, 2007, and Dec 31, 2019. Adherence to the current WHO recommendation of fan use below temperatures of 35°C only, fan use would have been recommended on 27·2 days (87·7%) of 31 hot weather days. According to our simplified thresholds for fan use (at temperatures <39·0°C for healthy young adults, <38·0°C for healthy older adults, and <37·0°C for older adults taking anticholinergic medication), fan use would have been recommended on 29·6 (95·5%) of 31 hot weather days in healthy young adults, 29·4 (94·8%) days in healthy older adults, and 28·8 (93·0%) days in older adults taking anticholinergic medication between Jan 1, 2007, and Dec 31, 2019.
Interpretation
Electric fan use, particularly for healthy young adults, would not have worsened heat stress on the majority of study days between 2007 and 2019. Our newly proposed thresholds for fan use provide simple guidelines that improve future heatwave fan use recommendations.
Funding
None.
... In Singapore and Thailand, in office rooms with air-conditioning (a semi-controlled environment) productivity studies were conducted [374,375]. In Singapore, despite causing lower thermal sensation and reduced thermal comfort, a lower air temperature (moderate cold exposure of 20 • C) increased mental arousal and increased performance in activities requiring attention [375]. ...
... In Singapore, despite causing lower thermal sensation and reduced thermal comfort, a lower air temperature (moderate cold exposure of 20 • C) increased mental arousal and increased performance in activities requiring attention [375]. In Thailand, research indicates that in order to maintain and increase productivity, indoor temperatures should be higher in the morning (26-28 • C, warmer thermal condition than PMV-ISO 7730) than in the afternoon and evening (24.5-26 • C) [374]. This finding may be related to the results obtained by Kakitsuba and White [376] in climate chamber experiments in Japan. ...
The aim of this paper is to review the literature on human thermal comfort in the built environment. First an overview about the subject area is presented. This is followed by a review of papers published in the last 10 years that examine the various sub-areas of research related to human thermal comfort. Some remarkable works about both the Fanger's and adaptive thermal comfort models are also discussed. This review does not contain simulation works and/or experimental studies without subjective results of people. As a result of the literature review, 466 articles were classified and grouped to form the body of this article. The article examines standards, indoor experiments in controlled environments (climate chamber) and semi-controlled environments, indoor field studies in educational, office, residential and other building types, productivity, human physiological models, outdoor and semi-outdoor field studies. Several research topics are also addressed involving naturally ventilated, air-conditioned and mixed-mode buildings, personalized conditioning systems and the influence of personal (age, weight, gender, thermal history) and environmental (controls, layout, air movement, humidity, among others) variables on thermal comfort.
... Their analysis showed that both types of thermal stressors have similar magnitude of impact on performance. Ngarmpornprasert and Koetsinchai [23], in a study of productivity of office workers, concluded that optimal productivity can be achieved by air-conditioning set points at 26e28 C during morning and at 24.5e26 C for the afternoon and evening hours. There are some studies done for offices [13,21,24] and one for classrooms [16] in all of which, an optimal temperature for performance has been found around 21 C. ...
... Fisk and Rosenfeld [20] even state that for a few types of tasks that involve high complexity or creativity, optimal thermal comfort and optimal performance may coincide while for most other task types, a slight thermal discomfort may raise arousal level to improve performance of mental work. A couple of studies also found that time of day can affect optimal environment for productivity [23,25]. Thus, apart from an expected variation due to individual preferences, task nature, duration, and time of execution can influence the optimal thermal environment for productivity. ...
This study presents a comparison of classroom learning performance between courses taught in naturally ventilated (NV) rooms and air-conditioned (AC) rooms. This is done to examine effect of thermal comfort standard followed — PMV based or adaptive thermal comfort — on learning. The same group of students, attending different courses in the two classroom types over two years, was chosen to avoid inter-student difference of aptitude and ability. Performance was measured on basis of final grades scored in the particular courses. Data from a set of transverse thermal comfort surveys was used to find levels of satisfaction prevalent amongst students about their thermal environment in the two room types. Statistical tests were carried out to do pair wise comparisons of the performance of students. Comparison results did not show significant difference in performance for the courses considered. It is concluded that ability and avenues to adapt may help maintain long term average performance over a range of thermal environments.
... One study analysed the time and temperature dependency of productivity in an office environment. The results indicate optimum productivity in the morning at 26-28 • C and in the afternoon at slightly lower temperatures of 24.5-26 • C (Ngarmpornprasert and Koetsinchai, 2010). Another study had a contrary finding regarding time dependency, PMV and self-perceived productivity (Bueno et al., 2023). ...
In the design of buildings with minimal environmental impact, the incorporation of higher energy flexibility is becoming increasingly relevant. This approach is associated with dynamic modulations in setpoint temperatures. Until now, a link between indoor temperatures and cognitive performance of workers has been assumed, leading to high energy consumption and overcooling of office environments in summer conditions. However, research focusing on the relationship between thermal indoor environments and cognitive performance has rarely considered the influence of dynamic temperatures or temporal effects. This is the first experimental study aiming to understand the impact of temperature in relation to time of day on the subjective perception of cognitive load and performance under various thermal conditions in real-world office environments. The results indicated no observable relationship between temperature setpoints (25-30 • C) and cognitive performance. Instead, the temporal dynamics of cooling rather than fixed and static temperature setpoints appeared to have an impact.
... Rasheed et al. (2021) found that there were significant differences in perceptions of comfort and productivity for those who spent less time and those who spent more time at work. Ngarmpornprasert and Koetsinchai (2010) found a satisfactory thermal condition for office workers by maintaining the temperature at 26-28 °C for morning periods and 24.5-26 °C for afternoon and evening periods. ...
This study investigates the overall comfort and productivity of Japanese office workers in mixed-mode office buildings. The indoor thermal environment is adjusted using the air-conditioning in Japanese office buildings to maintain thermal comfort and productivity. Thus, it is necessary to research thermal comfort and productivity to understand how occupants prepare themselves to be at a comfortable temperature and perform their daily tasks under mixed-mode (MM) and free-running (FR) modes. Environmental parameters such as air temperature, relative humidity, and so on were measured in 17 Japanese office buildings with the help of digital instruments, and thermal comfort transverse surveys were conducted for two years in Tokyo, Yokohama, and Odawara of Japan. The data were collected every once a month for a day visiting each building with the measurement instruments, together with the questionnaires. Almost 3000 votes were collected. This paper evaluates the overall comfort discussions followed by how the occupant could achieve their productivity. The occupants were found to be thermally comfortable and productive in the office. The most suitable comfortable temperature range for MM mode was found to be 22–26 °C and 23–25 °C for FR mode. The workers' productivity range is defined by the globe temperature range of 21–27 °C for MM and 20–27 °C for FR mode. The findings should be useful to suggest that whenever new office buildings are designed, these factors always need to be taken into consideration.
... Some studies [68,69] measured diurnal variations in indoor temperatures and collected the associated thermal perception votes but did not explicitly analyze changes in thermal perception with respect to the "time of day" variable and were, thus, excluded. The paper by Ngarmpornprasert & Koetsinchai [70] focusing on diurnal changes in productivity was also excluded because it did not specifically focus on thermal perception. ...
The circadian clock regulates diurnal variations in autonomic thermoregulatory processes such as core body temperature in humans. Thus, we might expect that similar daily fluctuations also characterize human thermal perception, the ultimate role of which is to drive thermoregulatory behaviors. In this paper, we explore this question by reviewing experimental and observational thermal comfort investigations which include the “time of day” variable. We found only 21 studies considering this factor, and not always as their primary analysis. Due to the paucity of studies and the lack of a specific focus on time-of-day effects, the results are difficult to compare and appear on the whole contradictory. However, we observe a tendency for individuals to prefer higher ambient temperatures in the early evening as compared to the rest of the day, a result in line with the physiological decrease of the core body temperature over the evening. By drawing from literature on the physiology of thermoregulation and circadian rhythms, we outline some potential explanations for the inconsistencies observed in the findings, including a potential major bias due to the intensity and spectrum of the selected light conditions, and provide recommendations for conducting future target studies in highly-controlled laboratory conditions. Such studies are strongly encouraged as confirmed variations of human thermal perceptions over the day would have enormous impact on building operations, thus on energy consumption and occupant comfort.
List of abbreviations: TSV: Thermal Sensation Vote; TCV: Thermal Comfort Vote; Tpref: Preferred Temperature; TA: Indoor Air Temperature; RH: Indoor Relative Humidity; Tskin: Skin Temperature; Tty: Tympanic Temperature; Tre: Rectal Temperature; Toral: Oral Temperature
... The assumption that comfortable thermal conditions are independent from the time of day is mainly the result of climate chamber experiments conducted in the 1970s and 1980s. [3][4][5][6] However, more recent studies seem to contradict this initial evidence [7][8][9] , which leaves the thermal comfort research community still very much in limbo. The problem is not exclusively theoretical and not only related to occupants' thermal comfort: a time-varying indoor thermal environment can have important practical consequences in terms of energy savings and for its potential contribution to promoting buildings' energy flexibility. ...
Recent research suggests that a time-varying indoor thermal environment can lead to energy savings and contribute to boost buildings' energy flexibility. However, thermal comfort standardization has so far considered thermal comfort criteria as constant throughout the day. In general, very little attention has been given to the ‘ time of day' variable in the context of thermal comfort research. In this paper, we show some evidence of a time-varying thermal perception by using: (1) data from about 10,000 connected Canadian thermostats made available as part of the ‘ Donate Your Data' dataset and (2) about 22,000 samples of complete (objective + ‘ right-here-right-now' subjective) thermal comfort field data from the ASHRAE I and SCATs datasets. We observe that occupants prefer colder thermal conditions at 14:00 and progressively warmer ones in the rest of the day, indistinctively in the morning and evening. Neutral temperature differences between 08:00 and 14:00 and 14:00 and 20:00 are estimated to be of the order of 2°C. We hypothesize that the human circadian rhythm is the cause of this difference. Nevertheless, the results of this study are only based on observational data. Thermal comfort experiments in controlled environmental chambers are required to confirm these findings and to better elucidate the effects of light and circadian timing and their interaction on thermal perception.
... Most sensitive to draught at the head region [25] Personal Control Support individual productivity, health and user satisfaction Temperature control [6,20,24,25,45,46,48,52,[54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] Humidity control [52,59,[71][72][73][74] ...
The indoor environmental quality (IEQ) of buildings can have a strong influence on occupants’ comfort, productivity, and health. Post-occupancy evaluation (POE) is necessary in assessing the IEQ of the built environment, and it typically relies on the subjective surveys of thermal quality, air quality, visual quality, and acoustic quality. In this research, we expanded POE to include both objective IEQ measurements and the technical attributes of building systems (TABS) that may affect indoor environment and user satisfaction. The suite of three tools, including user satisfaction survey, workstation IEQ measurements, and TABS in the National Environmental Assessment Toolkit (NEAT) has been deployed in 1601 workstations in 64 office buildings, generating a rich database for statistical evaluation of possible correlations between the physical attributes of workstations, environmental conditions, and user satisfaction. Multivariate regression and multiple correlation coefficient statistical analysis revealed the relationship between measured and perceived IEQ indices, interdependencies between IEQ indices, and other satisfaction variables of significance. The results showed that overall, 55% of occupants responded as “satisfied” or “neutral”, and 45% reported being “dissatisfied” in their thermal quality. Given the dataset, air temperature in work area, size of thermal zone, window quality, level of temperature control, and radiant temperature asymmetry with façade are the critical factors for thermal quality satisfaction in the field. As a result, the outcome of this research contributes to identifying correlations between occupant satisfaction, measured data, and technical attributes of building systems. The presented integrated IEQ assessment method can further afford robust predictions of building performance against metrics and guidelines for IEQ standards to capture revised IEQ thresholds that impact building occupants’ satisfaction.
... Its commonly known that HVAC performance doesn"t meet the expectation at the design phase. According to [2],the productivity of office workers could be Increased during morning, afternoon, and evening periods by 18%, 1% to 15%, and 7%, respectively by maintaining temperatures of HVAC systems at 26 • C−28 • C for morning periods and at 24.5 • C−26 • C for afternoon and evening periods. ...
Energy saving and productivity increase are two pivotal issues that face the world in these days. Heating, Ventilating and Air Conditioning (HVAC) systems one of essential sources of energy waste. Meanwhile, a comfortable thermal environment for buildings occupants, that could help in productivity improvement of office workers. Energy saving and occupant comfort highlight the importance of fault detection in HVAC systems. Fresh Air handling unit (FAHU) is an essential part of building HVAC system, automatic detecting of faults occurred in this unit could lead to energy consumption reduction and comfort and reliability improvement of this unit. Improved rule-based FD for FAHU is proposed in this paper. Many experiments and tests were conducted on the real reading. The conducted experiments reveals the ability of the proposed rule based FDD algorithm at detecting FAHU faults successfully.
Title: The Lighting Effect on Employee Performance in the Swarna Hutama Loka Asia, Bali Office Lighting is one of the essential aspects to support daily human activities. The result of the reflection of light onto an object allows us to see clearly and comfortably so that the work can be done correctly. A good workspace should fulfill the comfortability aspects of its users. One of them is visual comfort, which affects worker performance and productivity. Optimal employee performance and productivity can be achieved if the comfort points in the workspace comply with standards, i.e., the lighting design provisions for the workspace layout and the required light intensity. The research method used in this study is a comparative method with a combined methods approach, namely by comparing the results of qualitative (respondents' questionnaire) and quantitative (measurement of light intensity and Window Wall Ratio) methods according to SNI 03-6575-2001 standards: Procedures for designing artificial lighting systems in buildings. This method is used to analyze the lighting and visual comfort of the room and its relation to the productivity of Swarna Hutama Loka (SHL) Asia’s office users. Generally, if employees feel comfortable with the workplace's lighting intensity, their performance and productivity will also increase. However, it does not always work in some conditions due to factors other than lighting, such as furniture arrangement and environmental adaptation, which are not included in this research.
Purpose
Climate adaptation, energy efficiency, sustainable development and green growth are societal challenges for which the Facilities Management (FM) profession can develop solutions and make positive contributions on the organisational level and with societal-level effects. To base the emerging sub-discipline of sustainable facilities management (SFM) on research, an overview of current studies is needed. The purpose of this literature review is to provide exactly this overview.
Design/methodology/approach
This article identifies and examines current research studies on SFM through a comprehensive and systematic literature review. The literature review included screening of 85 identified scientific journals and almost 20,000 articles from the period of 2007-2012. Of the articles reviewed, 151 were identified as key articles and categorised according to topic.
Findings
The literature review indicated that the current research varies in focus, methodology and application of theory, and it was concluded that the current research primary addresses environmental sustainability, whereas the current research which takes an integrated strategic approach to SFM is limited. The article includes lists of reviewed journals and articles to support the further development of SFM in research and practice.
Research limitations/implications
The literature review includes literature from 2007 to 2012, to manage the analytical process within the project period. However, with the current categorisation and the access to the reviewed journals and articles, it is possible to continue with the latest literature.
Practical implications
The article provides an overview of theoretical and practical knowledge which can guide: how to document and measure the performance of building operations in terms of environmental, social and economical impacts? How to improve the sustainability performance of buildings? What are the potentials for and barriers to integrating sustainability into FM on strategic, tactical and operational levels?
Originality/value
The paper presents the most comprehensive literature study on SFM so far, and represents an important knowledge basis which is likely to become a key reference point for pioneers and scholars in the emerging sub-discipline of SFM.
3 . Similar economic projections on the energy implications of increasing the rates are again being thrown around, without consideration for the reasons the increases are being proposed in the first place or the expected benefits. Namely, most of us are living and working in unhealthful environments during our daily activities. Instead of concentrating on the energy cost alone, we should be looking at the greater positive impacts that are expected (by orders of magnitude larger). We should be finding design methods and technologies that could minimize or eliminate any financially negative impacts. This paper explores some of the many published technical justifications for providing optimal amounts of dilution ventilation. We will also offer some potential methods of minimizing the costs for providing the needed outside air, while simultaneously providing the flexibility in control for changes in space usage. The Big Carrots - Productivity and Health Everyone believes that they will never be the one on receiving-end of poor IAQ's big legal "stick". It will always be the other guy. Conversely, few have spent time considering the huge potential IAQ "carrot" that would provide more than sufficient motivation for most building owners to insist on exceptional indoor environments - PRODUCTIVITY and HEALTH. Indoor Air Quality (IAQ) is significant to achieving overall improvements in Indoor Environmental Quality (IEQ), which includes several comfort-related factors. It has been indicated in numerous studies that improving a building's indoor environment will also improve occupant productivity. Because aspects of IEQ and IAQ are normally addressed simultaneously and because IAQ is typically not addressed in isolation in new building design, we will for practical purposes equate the research references for IEQ to IAQ, using them almost interchangeably for the purposes of this discussion. In doing so, we identify the need for future IAQ and ventilation-specific research related to their impact on productivity and health. An early study in Europe by Professor Fanger showed that indoor air quality has an impact on human comfort and health, and documents for the first time that it also has a significant impact on human productivity in offices 1 .
One of the uses of ISO 7730 (predicted mean vote, PMV) is to predict the thermal sensations of people in buildings. This application is examined, using the ASHRAE database of field-studies. Taking these world-wide data as a single distribution, PMV is free from serious bias. There exist, however, underlying biases in relation to all contributing variables, and a further bias related to the outdoor temperature. These biases often combine to produce a substantial bias in PMV. In surveys of individual buildings, PMV often differs markedly and systematically from the actual mean vote, both for naturally ventilated (NV) and for air-conditioned (AC) spaces. Possible origins of the biases are discussed, and it is shown that it would be possible to modify PMV substantially to reduce them. Environmental consequences of the use of PMV are discussed. It is concluded that ISO 7730 in its present form can be seriously misleading when used to estimate thermal comfort conditions in buildings.
Moderate heat stress is believed to affect mental performance by lowering levels of arousal. Conscious effort can counteract this effect. In most experiments, raised temperatures are perceived at the start by subjects and can act as a stimulus to exert conscious effort. In practice, temperatures usually rise slowly and may therefore have a more marked effect. Thirty-six male and 36 female 17-year-old subjects in standard cotton uniforms (0.7 clo) were exposed in groups of four in a climate chamber to rising air-temperature conditions typical of occupied classrooms, in the range 20--29 degrees C. The maximum rate of rise was 4 degrees C/h. Each group performed mental work during three successive periods of 50 min with 10-min breaks between. During each break the air temperature was reduced by 3 degrees C. Sentence comprehension was significantly reduced by intermediate levels of heat stress in the third hour. A multiplication task was performed significantly more slowly in the heat by male subjects, showing a minimum at 28 degrees C. Recognition memory showed a maximum at 26 degrees C, decreasing significantly at temperatures below and above, and an independent measure of degree of certainty in recall showed a maximum at 27 degrees C. These findings are in accordance with the hypothesis of reduced arousal in moderate heat stress in the absence of conscious effort.
The objectives of this chapter are to explore the economic impact of unacceptable environmental control in buildings and to propose some initial steps that might be taken to improve health and productivity through cost effective control of the indoor environment. To address these objectives, the existing stock of buildings is characterized for its ability to provide for the health and comfort of occupants. Costs associated with owning and operating these buildings are then discussed on a micro- and macroeconomic scale.
The insulation provided by seven different chairs was measured using an articulated, thermal manikin in an environmental chamber. The manikin was tested nude and while wearing several different indoor clothing ensembles. Data were collected with the manikin sitting in the different chairs and standing. Results indicated that clothing insulation decreased when the manikin was sitting (in a net chair) as opposed to standing. However, when the manikin sat in real chairs, the insulation value increased 0.1 to 0.3 clo. The amount of the increase was related to the amount of chair surface area in contact with the body. In addition, the Iclu clo values for chair insulation can be added to Iclu values for garments to determine the intrinsic insulation around a person for use in thermal comfort models.
In Indoor Air 2002: Proceedings of the 9th International Conference on Indoor Air Quality and Climate, Vol. 1, H Levin, ed., Indoor Air 2002, Santa Cruz, California, 2002, pp. 1032-1037
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.
This theoretical study reports on the assessment of productivity loss in air-conditioned office buildings using the PMV approach and makes use of Wyon’s reviews [D.P. Wyon, P.O. Fanger, B.W. Olesen, C.J.K. Pedersen, The mental performance of subjects clothed for comfort at two different air temperatures, Ergonomics 18 (1975) 358–374; D.P. Wyon, Individual microclimate control: required range, probable benefits and current feasibility, in: Proceedings of Indoor Air ’96, Institute of Public Health, Tokyo, 1996; D.P. Wyon, Indoor environmental effects on productivity. IAQ 96 Paths to better building environments/Keynote address. Y. Kevin. Atlanta, ASHRAE, pp. 5–15] as the basis to compare and to relate how the productivity loss could be minimised through improved thermal comfort design criteria. The finding shows that task-related performance is significant correlated with the human perception of thermal environment that in turn is dependent on temperatures. Different combinations of thermal criteria (air velocity, clo, metabolic, etc.) can lead to similar PMV value and the PMV equation is useful to predict productivity loss that is due to the rate of change in thermal conditions. The study also highlights the issues that remain to be resolved in future research.
A re-analysis is given of data from the Report of the New York State Commission on Ventilation (1923). Four climate chamber experiments are examined, in which typewriting performance was studied at air temperatures of 20 and 24°C. Sixteen male subjects worked for five days, seven hours a day, in a balanced design with different temperatures in morning and afternoon. Eight female subjects worked for 10 days under similar conditions. A further 16 male subjects worked for six days in a balanced design with three full days at each temperature, and seven female subjects worked for 10 days with five full days at each temperature. In every half-day of these experiments, during which subjects otherwise were obliged to work very hard, there was a period during which subjects could work at a typewriter if they chose, but were unsupervised and free to converse or rest- Tables of raw data from the typewriting task were published. By using non-parametric statistical methods that were not available at the time of original publication, it is shown that subjects performed considerably and significantly more work at 20° than at 24°C on the typewriting task
Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in a normally furnished office space (108 m3) ventilated with an outdoor airflow of 3, 10 or 30 L/s per person, corresponding to an air change rate of 0.6, 2 or 6 h-1. The temperature of 22 degrees C, the relative humidity of 40% and all other environmental parameters remained unchanged. Five groups of six female subjects were each exposed to the three ventilation rates, one group and one ventilation rate at a time. Each exposure lasted 4.6 h and took place in the afternoon. Subjects were unaware of the intervention and remained thermally neutral by adjusting their clothing. They assessed perceived air quality and SBS symptoms at intervals, and performed simulated normal office work. Increasing ventilation decreased the percentage of subjects dissatisfied with the air quality (P < 0.002) and the intensity of odour (P < 0.02), and increased the perceived freshness of air (P < 0.05). It also decreased the sensation of dryness of mouth and throat (P < 0.0006), eased difficulty in thinking clearly (P < 0.001) and made subjects feel generally better (P < 0.0001). The performance of four simulated office tasks improved monotonically with increasing ventilation rates, and the effect reached formal significance in the case of text-typing (P < 0.03). For each two-fold increase in ventilation rate, performance improved on average by 1.7%. This study shows the benefits for health, comfort and productivity of ventilation at rates well above the minimum levels prescribed in existing standards and guidelines. It confirms the results of a previous study in the same office when the indoor air quality was improved by decreasing the pollution load while the ventilation remained unchanged.
Evaluation of association between indoor air climate well-being and productivity
- S O Hanssen
A comparison of methods for assessing thermal sensation and acceptability in the field
- G S Brager
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- C C Benton
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Indoor environmental quality effects on productivity
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Field studies and climate chamber experiments in thermal comfort research
- M A Humphreys
- M.A. Humphreys
Validation of predicted mean vote model
- Rj Dear
- A Auliciems
Predicted vs recorded summer thermal responses in air-conditioned and naturally ventilated dwelling in Israel
- M Paciuk
- R Becker
The impacts of thermal condition and illuminance on self-rated productivity of office workers
- S Ngarmpornprasert
- W Koetsinchai
Thermal comfort in naturally ventilated versus air-conditioned offices
- N A Oseland
- S Yoshizawa
- K Kimura
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- T Iwata
Mental performance by secondary school pupils in relation to the quality of indoor air
- G Smedje
- D Norback
- C Edling
Bangkok Climate (in Thai) Available at
- Meteorological Thai
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Environmental perception, SBS symptoms and performance of office work under combined exposure to temperature, noise and air pollution
- T Witterseh
ISO 10551 Ergonomics of the thermal environment—Assessment of the influence of the thermal environment using subjective judgement scales
- International Organization for Standardization
Thermal insulation of chairs
- E A Mccullough
- B W Olesen
- E.A. McCullough
Validation of predicted mean vote model
- R J De Dear
- R.J. Dear de
Impact of reduced air temperature and increased radiant temperature on perceived air quality, thermal comfort, SBS symptoms and performance
- P Foldberg
- G Reimann
Bangkok Climate (in Thai)
- Thai Meteorological Department