Thermal Comfort Perception Research Articles

Perceptions of thermal conditions in contemporary high-rise apartment buildings under different temperature control strategies

While occupancy-based control and other demand management control strategies have demonstrated potential, little is known about how these changes in heating, ventilation, and air-conditioning (HVAC) control impacts occupants’ perception of the thermal conditions in their home. In this paper, occupants’ thermal comfort perceptions and use of thermostat overrides under three different control strategies (programmable thermostat operation, occupancy-reactive control, and pre-cooling/pre-heating for load-shifting) are analyzed. Thermal comfort data were collected through six occupant surveys administered to 54 participants in the summer and winter months in two high-rise condominium buildings in Toronto, Canada. Minor changes to reported thermal sensation scores were observed in both the occupancy-based and load shifting control scenarios, however, overall reported thermal sensation scores remained neutral. Occupants’ use of overrides did not change significantly during occupancy-based control periods, however, during load shifting control, occupants frequently overrode strategy temperature set-points – which indicates that many participants likely experienced thermal discomfort beyond their tolerance level. Occupants’ use of strategy overrides during load shifting control strategy operation in the cooling season significantly reduced strategy efficacy. Reducing the maximum temperature setback during load shifting control to 3 °C during the cooling season was recommended to reduce occupant override and improve realized peak-period load reductions.

Outdoor thermal benchmarks and thermal safety for children: A study in China's cold region

Outdoor spaces in parks designed for children's recreation are highly valued facilities that support physical health and well-being for parents and youth. Key to their use is the perception of thermal comfort. To this end, a questionnaire study of thermal perception in representative open spaces in a children's park in Xi'an, China was conducted. Child thermal benchmarks in Xi'an and thermal safety were evaluated using the universal thermal climate index (UTCI) with material surface temperatures (Ts) in open spaces. Bioclimatic design strategies for open spaces were proposed based on children's thermal benchmarks and Ts. We draw four conclusions: 1) Globe temperature (Tg) and air temperature (Ta) were the primary meteorological factors influencing children's thermal sensation. 2) Neutral UTCI (NUTCI) for male and female children were 13.7 °C and 15.3 °C, NUTCI ranges were 6.1–21.3 °C (male) and 8.1–22.5 °C (female), the preferred UTCIs were 20.0 °C (male) and 19.7 °C (female), and acceptable UTCI ranged from 6.5 to 26.4 °C (male) and 5.7 to 27.3 °C (female). 3) Ts of asphalt, water permeable bricks, wood (ground) and wood (chair) were high in the sun, threatening children's thermal safety; Ts of all tested materials was low in the shade with no heat risk in normal use. 4) Bioclimatic design strategies were proposed based on children's thermal benchmarks and Ts of materials including vegetation, materials and built facilities. The results provide guidelines for urban planners and landscape architects to create age-appropriate open spaces that mitigate urban heating, reduce summer sun exposure and improve park usability in China's cold region.

Ex-post evaluation of residential insulation program in the city of Temuco, Chile

There is abundant literature about the impact of residential insulation on energy consumption using different methods. However, ex-post evaluation methods have not been used yet, which are helpful when the participants in a program are not chosen randomly. Therefore, this study performs the first ex-post evaluation of a residential insulation program using the “matching with differences-in-differences” method. This non-experimental method allows obtaining the causal impact of the program since it controls for observable factors and non-observable factors that are invariable over time. The data comes from a unique survey that includes energy consumption for heating and control variables for households benefited and not benefited by the program, both in the year before and after the retrofit. The results show that the residential insulation program does not significantly reduce energy consumption or external PM2.5 emissions in the treated dwellings. Still, there is a significant increase in the perception of thermal comfort associated with the rebound effect. Thus, it is concluded that the program has not been an effective tool to reduce air pollution, but it improves the quality of life through an increase in thermal comfort.

Indoor thermal comfort assessment in office buildings in hot-humid climate

This paper aims to assess the user’s perception of thermal comfort and air conditioning in office buildings in Batu Pahat, Johor area. Field experiments were conducted utilizing environmental measurement and Post Occupancy Evaluation (POE) in Batu Pahat District Land Office (Pejabat Daerah) and (C2 and ORICC) office buildings in the Universiti Tun Hussien Onn Malaysia (UTHM). The environmental measurement was conducted using thermal comfort station BABUC A, whereas the POE was based on the ASHRAE 55-2010 standard. The environmental parameters included relative humidity, air temperature, and air velocity. They were measured and compared with MS-1525, ASHRAE 55, and ISO 7730 standards. Results indicated that indoor air temperature in C2 has good compliance with MS-1525, ASHRAE 55, and ISO 7730 standards and criteria with a measured comfort range of 24 °C-26 °C. Whereas for ORICC and Pejabat Daerah, temperatures were a bit lower than the suggested range. At the same time, the range of relative humidity was found to be higher than ASHRAE limits but complied with other standards. Moreover, adequate air velocity standards were not met in the three office buildings, in which they were measured within 0.4-0.5 m/s range. Furthermore, thermal comfort levels and the POE survey results indicated that users’ in hot tropical office buildings could acclimate to a higher indoor environment than what was suggested by standards.

Are low-income mass housing envelops energy efficient and comfortable? A multi-objective evaluation in warm-humid climate

This study evaluates and compares the performance of the commonly constructed mass housing envelops in India with alternative building envelop constructions. These alternative construction scenarios are created with a material library comprising of the available alternative roofing and walling system combinations including some common emerging construction technologies standardized and advocated by the Building Materials and Technology Promotion Council of India. The common trend of housing envelop constructions in the country involves ordinary burnt brick walls and reinforced cement concrete roofing and beam-column system which is referred to as the base case building envelop in our study. We consider initial investment costs, thermal comfort perception and the initial embodied energy in a multi-objective evaluation framework for assessing free running building envelops. Rat trap bonded brick walls, glass fibre reinforced gypsum construction, light gauge framed steel (LGFS) constructions, monolithic concrete (MC) construction system, reinforced concrete ribbed roof and compressed stabilized earth block (CSEB) walls and CSEB filler roof slabs make repeated appearances in the multi-objective optimal solution sets or Pareto optimal solution sets. CSEB construction has lowest initial embodied energy, LGFS gives minimal thermal discomfort whereas MC construction system reports least construction cost. A predominance of lean envelop constructions is observed in the Pareto optimal solution sets considering minimization of construction cost, thermal discomfort and construction embodied energy.

A regression-based three-phase approach to assess outdoor thermal comfort in informal micro-entrepreneurial settings in tropical Mumbai.

Urban heat poses a public health risk to the residents of megacities in developing countries because the population spends a significant amount of time outdoors to work and socialize with limited cooling resources. Understanding the drivers of outdoor comfort and heat stress in informal work settings is important to design climate-sensitive outdoor spaces and reduce heat vulnerability. We present outdoor thermal comfort perceptions (OTCPs) of people engaged in outdoor micro entrepreneurial activities in Mumbai using seasonal surveys and biometeorological observations. We propose a three-phase approach to analyze the relative importance of climatic and non-climatic variables for OTCPs. The first phase evaluates the seasonal and intra-neighborhood variation of thermal sensation votes (TSV) with respect to physiological equivalent temperature (PET) and air temperature. Second, we include physiological parameters to evaluate the seasonal and intra-neighborhood variation of overall sensation votes (OSV). Third, we consider aggregated survey responses and include behavioral and perceptual variables to determine their relative significance. We employ three linear modeling techniques to assess model performance in explaining the variability of OTCP using OSV as dependent variable. Results reveal that microclimatic parameters alone are unable to explain the variability of OTCP. Our results yield a neutral PET value (PETneutral) of 23.75 °C for Mumbai in the winter. PETneutral was higher for activities at the clothing market compared to other micro entrepreneurial activities. Acclimatization significantly improved comfort in the summer, while evaporative cooling was beneficial in the winter. Further, an ANCOVA and ordinal logistic regressions demonstrate the importance of behavioral attributes (presence in the location, expectation, beverage intake) in explaining the variance in OTCP. Our study also reveals that wind speed and humidity play an important role in shaping overall comfort in the Mumbai neighborhoods.

Influence of environmental variables on thermal comfort and air quality perception in office buildings in the humid subtropical climate zone of Brazil

This study evaluates the influence of environmental variables on users’ thermal comfort and air quality perception in the humid subtropical climate of Florianópolis, southern Brazil. A building with central air-conditioning system and three mixed-mode buildings, which alternated between natural ventilation and air-conditioning modes, were investigated. Statistical analyses were performed considering environmental data collected in situ between 2014 and 2016 – using microclimate stations, a portable thermo-anemometer and a CO2 analyser – and users’ subjective responses obtained by means of an electronic questionnaire. Results showed a direct influence of air temperature and humidity ratio and indirect influence of air movement on thermal comfort. In addition, thermal, air movement and humidity sensation, preference and acceptability affected thermal comfort and air quality perception, highlighting the importance of carrying out a complete assessment of users’ perception of the thermal environment. This work supports the use of the ASHRAE 55 adaptive thermal comfort model for mixed-mode buildings under natural ventilation operation. Based on the results obtained in this study, the use of hybrid ventilation strategy is recommended for energy savings due to reducing the use of air-conditioning and improving indoor air quality as there is a decrease in air pollutants level.

Thermal Comfort Of The Outdoor Transition Space In the Dean’s Office Building

The increase in the transmission of the COVID-19 disease, creating an effort to prevent transmission by controlling total of space users in the Dean’s Office Building, University of Bengkulu to avoid overcrowding users of space in buildings. The control has an impact on the increasing number of space users in the transition space of outdoor (terraces, hallways, corridors) in the eight Dean’s Office Buildings. The thermal comfort of the outdoor transition space needs to be considered because the post-pandemic adaptation behavior causes the change in the function of the transition area as buffer between outdoor and indoor spaces, is currently becoming a waiting room for entering buildings with uncertain waiting times. In addition, University of Bengkulu is located in coastal area with air temperatures during the day between 30 °C- 34 °C and wind speed ranging from 0-2,2 m/s. The purpose of this research is to determine the perception of thermal comfort of space users in the transition space, Dean’s Office Building, University of Bengkulu. Measurement data in the form of air temperature, air humidity, and wind speed at the peak of the dry month were carried out at 08.00-16.00 for 10 working days and interview data on the perception of thermal comfort of space users. Interview and measurement data will be inputted on the Ray-man measuring instrument to obtain the PET, PMV, SET values.

Thermal comfort perception in naturally ventilated affordable housing of India

ABSTRACT Indoor thermal comfort is critical to building sustainability besides improving occupants’ health, well-being and productivity. However, the applicability of the existing comfort standards within different climatic conditions and contextual settings is often in question. This study presents the findings from a longitudinal thermal comfort study conducted in low-income affordable housing in Mumbai, India. Surveys were conducted in three distinct seasons within a warm–humid climate. The linear regression method yielded a mean neutral temperature of 28.3°C and a wide comfort band ranging from 24.6°C to 32.2°C indicating high thermal adaptation among the occupants. The preferred temperature was found to be 26.3°C. Adaptive comfort standards, ASHRAE and the National Building Code of India prescribed a narrow range of comfort and were ineffective in predicting comfort conditions within affordable housing units. The role of income in shaping comfort expectations was established, lending support to the economic dimension of comfort. The results would be helpful in providing design recommendations for the future affordable housing stock and the development of an adaptive comfort model for vulnerable low-income communities.

Distributed and localized cooling with thermoelectrics

G. Jeffrey Snyder is a Professor of Materials Science and Engineering at Northwestern University in Evanston Illinois. His interests are focused on engineering of electronic and thermal properties, and he is well known for his work on thermoelectric materials. He has developed new methods of electron band structure engineering and microstructure engineering of thermal and electrical properties of complex materials. His interdisciplinary approach stems from his background in solid state chemistry at Cornell University and the Max Planck Institute for solid state research, applied physics at Stanford University, and thermoelectric materials and device engineering at NASA/Jet Propulsion Laboratory and California Institute of Technology (Caltech).

The what, why, and how of changing cooling energy consumption in India’s urban households

India’s urbanising middle class is at the brink of an unprecedented increase in residential cooling demand, yet little is understood about the dynamics of changing cooling consumption. Based on empirical analyses, this research examines a set of fundamental questions around India’s cooling transition. How is cooling conceptualised and what cooling strategies do households use? How, when and why are people purchasing and using their air conditioners (ACs)? Who is buying energy-efficient ACs? Is cooling consumption gendered? Using descriptive statistics, machine learning, and regression analysis to characterize AC usage, we examine a sample dataset (n = 2092) that is representative of areas in Delhi with above average AC penetration. We unpack perceptions of thermal comfort, and characterize the conditions under which households have greater AC use and make energy efficient purchase choices. AC usage is found to be a function of household habits (such as exposure to ACs in the workplace or schools), structural factors, and socio demographic features. While most ACs are in the middle energy-efficiency range, preferences, behaviours and awareness around energy efficiency are found to affect AC use as well as influence the purchase of more efficient ACs. Notable gender differences are observed, and women are found to be less involved in decision-making around cooling appliances and less aware of the technical know-how or energy-efficient schemes. Policy recommendations for a low-carbon cooling trajectory are discussed.

Methodology for calculating an atmospheric pressure-sensitive thermal comfort index PMVaps

Several software tools have been created to calculate the indices Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) by following Fanger’s method, which is valid only for atmospheric pressures close to 1 atm.The main objective of this work is to propose a formulation named PMV-PS for predicting an atmospheric pressure-sensitive thermal comfort index (PMVaps). The effort conducted by the authors was focused on the identification of the variables and expressions used in the calculation of thermal comfort index that may be affected by the change of the atmospheric pressure. The best known formulations for each individual aspect were introduced in the new model. It has been calibrated with data at sea level and tested for a set of cases considering different values of metabolic activity rate, thermal resistance of clothing and environmental parameters. At sea level there are negligible differences between PMV and PMVaps. However, when atmospheric pressure deviates from 1 atm, large differences between PMV and PMVaps are observed. PMV-PS model is a good starting point for further investigations into the influence of atmospheric pressure on thermal comfort perception and assessment, under real conditions, or using hypobaric chambers. Moreover, due to the subsisting doubts resulting from the analysis of published studies, it is crucial to perform further experimental work with high statistical significance i) to test the validity of the adopted correlations for the relationship between metabolic rate and atmospheric pressure and ii) to investigate in deep thermal comfort sensation of individuals used to live at altitude and of individuals with short-term exposure to an environment different from what they are used to live.Based upon the main findings of the present work, not considering the atmospheric pressure effect in PMV index may lead to significant errors.

DESIGNING PUBLIC SQUARES TO OPTIMIZE HUMAN OUTDOOR THERMAL COMFORT: A CASE STUDY IN SAFRANBOLU

Within the scope of the study, thermal comfort analysis was performed using the ENVI-met program of the Misak-ı Milli Square in Safranbolu, and it was determined that the thermal comfort perception of the square as slighty warm-warm. For this reason, a new design proposal has been submitted for the square. In the proposal, the green ratio and the number of trees was increased, the type and location of the trees was changed. The flooring materials was replaced with a stone covering with a higher albedo and new functional suggestions were made for the square. As a result of the thermal comfort analysis of the new proposal, the thermal comfort perception in the square was neutral and the thermal dissatisfaction rate was reduced below 14.5%. In result of the study, it was underlined that the ratio of green areas and the tree type, number and location that constitute it and the choice of flooring materials are important parameters in providing the thermal comfort of the square.

Thermal comfort perception of hijab usage among young Muslim women for sports activity

Purpose The purpose of this paper is to investigate the perceived thermal comfort experienced by active Muslim women (AMW) wearing hijabs determined by their experience of comfort sensation while doing sports activities or regular exercises. This study also examines whether the casual hijabs which are widely used among AMW are able to supply the appropriate comfort for active purposes. Design/methodology/approach This study used the quantitative method using survey questionnaires to collect 100 primary data obtained from AMW respondents who are university students located around the Klang Valley region in Malaysia. Findings Based on the overall results, this study suggests that the common hijabs that are used for casual applications do not offer sufficient comfort to Muslim women while performing sports activities or regular exercises. Research limitations/implications The outcome of this study will help to gain a better understanding on hijab preferences and comfort experienced from the viewpoint of regular hijab users. The information will assist industries to consider the selection of the right materials when developing sportswear hijabs to provide better comfort for more AMW in the near future. The method used in this study is useful to gain information on consumer’s profile and value-added details about the discomfort aspects of hijab which are scarce in the existing literature on thermal comfort. Originality/value This study was conducted to explore the type of hijabs commonly worn by AMW while performing sports activities and to obtain their views on the perceived thermal comfort.

Comparative analysis of user comfort and thermal performance of six types of vernacular dwellings as the first step towards climate resilient, sustainable and bioclimatic architecture in western sub-Saharan Africa

The purpose of this study is to assess thermal comfort conditions in vernacular dwellings in western sub-Saharan Africa. The paper identifies six vernacular and low-tech building typologies specific for selected countries. Comparative analysis of user comfort and thermal performance of case studies, representative for each typology was carried out, as the first step towards climate resilient, sustainable and bioclimatic architecture in the region of the investigation. The measurements of temperature, relative humidity, indoor air quality and daylighting as well as the user satisfaction survey were performed in February 2019 and repeated in August 2019. It was determined that during the hot and dry season, the indoor temperatures of 26–30 °C were achieved in traditional dwellings (Typologies I-IV) and accepted by 60–70% of inhabitants, while in ‘modern houses’ (Typology VL2 and VI) the level of user thermal comfort was significantly lower (only 20% felt comfortable). During the colder wet season 90% of users felt comfortable in vernacular dwellings and only 50% in ‘modern houses’. High levels of CO2 concentrations were detected in dwellings with tight envelopes (1800–1900 ppm) due to the lack of adequate ventilation. In pursue of solution various air exchange rates were examined to check how they comply with the user thermal comfort perception. It was found that the optimal ventilation should provide the air exchange rate of 0.5 VR/h which allows to fulfil minimal demands of ISO and ASHRAE standards. The study established the baselines for sustainable, bioclimatic, affordable housing model for western sub-Saharan Africa.

Are running socks beneficial for comfort? The role of the sock and sock fiber type on shoe microclimate and subjective evaluations

This study evaluated the effect of socks (different in fiber type) and the effect of not wearing a sock on perceptions of thermal comfort in relation to changes in foot skin temperature and shoe microclimate (temperature and humidity) during rest and exercise. Ten females completed five trials on separate occasions. Four socks (cotton, wool, polyester, Coolmax) and no sock were evaluated. Trials were conducted at 23°C, 50% relative humidity and consisted of rest (10 min seated), treadmill running (40 min, 7.5 km·h−1) and recovery (15 min seated). Foot skin temperature and shoe microclimate were measured at seven sites on the right foot. Foot skin hydration was measured at nine foot sites. Perceptual responses were recorded. Foot thermo-physiological and foot perceptual responses were similar for all sock conditions ( p > 0.05). Similar foot thermo-physiological responses were also observed between the sock and no sock conditions ( p > 0.05). Interestingly, however, not wearing a sock resulted in greater perceptions of foot wetness, stickiness and discomfort ( p < 0.05). As tactile interactions caused by foot movement within the shoe are strong predictors of foot wetness perception (a key contributor to wear discomfort), socks are important in reducing the tactile cues generated. The sock is therefore an important area for development and relevant for overall improvements in footwear comfort.

Moving to a green building: Indoor environment quality, thermal comfort and health

A global movement towards the creation of “green” buildings is currently underway. Although driven primarily by an external environmental agenda such as energy or carbon, there is growing recognition that greener buildings could affect the Indoor Environment Quality (IEQ). However, localised green building codes, especially in the developing world, often do not systematically recognise IEQ or health as crucial issues, which therefore remain understudied. Since the developing world alone is expected to nearly double current global built floor space by 2050, it is crucial that green buildings perform holistically to be effective. Here, we follow 120 employees of a single organisation as they transition from four conventional office buildings to the first green building (GB), designed to the local Jordanian Green Building Guide. We ask if the move has a positive effect on occupant perception of IEQ, thermal comfort and prevalence of Sick Building Syndrome (SBS), using a repeated-measures protocol. Statistically significant differences in thermal conditions, positively biased towards the GB, were observed across the move, and this enhanced occupant thermal comfort. Surprisingly, no significant improvement in occupant perception of air quality, visual and acoustic comfort was detected after moving to the GB, while odour, mental concentration, and glare were perceived to be poor in the GB and associated with an increase in the prevalence of SBS symptoms. Hence, our results support the growing concern that green buildings may create unintended consequences in terms of occupant comfort and health in the pursuit of a better thermal environment and energy efficiency.

The Relationship Between Helmet Weight, Cognitive Performance, and Mental Workload.

Introduction:This study sought to examine the effects of helmet weight on cognitive performance and mental workload. Twenty participants were studied in 3 one-hour sessions.Methods:The study participants were requested to read and work with computers under the following 3 conditions: wearing no helmets, wearing a helmet that weighed 800 g (A), and a helmet weighing 1500 g (B). “N-back” task and Continuous Performance Test (CPT) were employed to assess cognitive performance. At the same time, NASA-TLX and Thermal Comfort and Fatigue Perception Scale were used to evaluate mental workload and comfort. At the end of the intervention sessions, perceived mental workload, thermal comfort, and fatigue in the head were measured. Moreover, the research participants’ cognitive performance was gauged before and after the sessions.Results:The present study findings revealed that helmet weight significantly impacted cognitive performance (P<0.001). However, no significant difference was detected in the participants’ mental workload before and after the intervention.Conclusion:Helmet weight could affect cognitive performance. Therefore, in designing helmets, the helmet’s weight should be considered an essential factor.HighlightsHelmet weight significantly impacted cognitive performance.The results showed that the perceived mental workload was not influenced by helmet weight.Designing helmets, the helmet’s weight should be considered an essential factor.Plain Language SummaryThis study examined the effect of helmet weight on brain performance. The results showed that the perceived mental workload was not influenced by helmet weight. However, brain performance declined as a result of wearing heavier helmets. Furthermore, the perceived local fatigue in the shoulders and neck increased after wearing heavier helmets. Thus, manufacturers should consider helmet weight while designing helmets and developing the relevant standards.

Capabilities of the Regional Cabin Demonstrator as digital twin for a future test mock-up

Digital twins are essential for Industry 4.0 and the digitalization of research, development and manufacturing. By now, the models contain more and more information and are already often highly complex systems. However, an important step is to keep the model as simple as possible in order to reduce computing resources and the associated simulation time. The Indoor Environment Simulation Suite (IESS) is a tool to generate a zonal model from a CAD geometry. It is designed to simulate the transient indoor climate in a short time, while still considering all important physical processes (heat conduction, radiation, convection). After the zonal model has been generated, the user can parameterize it specifically to the application and couple it with other models when needed. Here, a new approach is to integrate a thermo-physiological model of the human body in order to make statements about the human perception of thermal comfort. This is of particular interest in early development phases in order to assess air conditioning strategies as well as structural or technical adaptions due to thermal bridges or other influences on the cabin climate. In this paper a concept will be presented where the zonal model is coupled with the thermo-physiological model to investigate selected case studies on how thermal comfort in a regional aircraft can be assessed and considered in early design phases. The cabin model is based on a new type of regional aircraft for which a mock-up is currently being built in order to perform subject test at the Fraunhofer Institute in Holzkirchen. The thermal model can thus make statements in advance about how test scenarios should be carried out in order to gain the greatest possible benefit from the subject study tests, where the number of different tests is limited.

Determining the diurnal variation in comfort temperature in school buildings in the warm and humid climate

PurposeThe paper aims to determine the thermal comfort perception of schoolchildren from a warm and humid environment. There is a concern about the effect of high temperature on the health and academic performance of schoolchildren.Design/methodology/approachObjective and subjective methodological approaches were adopted to collect data during the fieldwork in the selected primary schools. ASHRAE adaptive comfort model was adopted to analyze the data.FindingsThe paper provided empirical results about the comfort requirements of schoolchildren from the warm and humid environment. During the occupied school time, the studied schoolchildren were found to tolerate temperatures higher than the upper limit temperature recommended by ASHRAE Standard 55. The paper recommends that the studied children may not need any active ventilator to be thermally comfortable during the occupied school hoursOriginality/valueThe paper found the range of temperatures that schoolchildren from the warm and humid environment can adapt to. The information may be useful to architects, engineers and facility managers