Thermal Comfort Sensation Research Articles

Impact of elevated air velocity on subjective thermal comfort sensation under asymmetric radiation and variable airflow direction

Buildings rarely have homogeneous thermal indoor environments. Transparent building elements are one of the sources of thermal asymmetry. Using advanced personalised ventilation systems, the discomfort caused by radiation asymmetry may be reduced. A series of measurements involving 20 subjects were carried out under controlled environmental conditions to investigate subjective thermal comfort in the case of asymmetric radiation combined with the personalised ventilation. Analysis showed that the subjective thermal comfort sensation without a personalised ventilation system is similar to the calculated predicted mean vote. However, there is a significant difference between the responses of female and male participants. The advanced personalised ventilation system lowers the subjective thermal comfort sensation, but does it differently for men and women. The skin temperatures of the hands of the women were significantly lower than that of the men. In the case of the men, radiation asymmetry led to significant differences in the facial skin temperature, while in the case of the women, the differences in the facial skin temperature were not significant.

Pemilihan dan Implementasi Strategi Peningkatan Kenyamanan Termal Ruang Kuliah

Optimum conditions help us think and work better. Thermal comfort in lecture buildings is important to maintain students’s comfort and help them concentrate on study. The fastest way to achieve expected thermal comfort inside the lecture room is using air conditioner, however, compensation on high electricity bills and degradation of the environmental quality has to be made. Therefore, the aim of this paper is to find and promote several environmental friendly strategies which can provide comfort to users in one hand, but also can reduce energy consumption in another hand. There have been several strategies in records to increase thermal comfort in buildings. To select the best and the most appropriate alternative, Analytical Hierarchy Process method was used by setting the criteria, sub-criteria, and alternatives to increase thermal comfort in lecture buildings of Andalas University. To test the selected alternative, thermal comfort inside two lecture rooms were evaluated experimentally. The comfort level was evaluated using PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied) model. For all experimental conditions, PMV and PPD results and individual thermal vote results showed a good match statistically meaning that the PMV and PPD models could predict thermal condition inside the lecture rooms. Results also showed that the presence of natural vegetation infront of glass windows of the lecture rooms statistically improved thermal comfort sensations of students under natural ventilation mode and reduced thermostat setting under air conditioning mode.

C-68 水まわり空間を中心とした省エネルギー性と快適性に関する研究 : (第9報)暖房方式・湯温が温熱快適感と身体ストレスに及ぼす影響に関する検討

C-68 水まわり空間を中心とした省エネルギー性と快適性に関する研究 : (第9報)暖房方式・湯温が温熱快適感と身体ストレスに及ぼす影響に関する検討

Development of an Integrated, Personalized Comfort Methodology for Office Buildings

Despite the significant progress observed over the last decades, the European building stock still consumes significant amounts of energy (39% of the total final energy), whilst it does not always provide the conditions required for occupants’ well-being and thermal comfort sensation. In order to achieve the goal of nearly or even zero energy buildings, a deep refurbishment of the building stock is imperative. As the literature indicates, a firm evaluation of indoor conditions is essential, while having at the epicenter the occupants’ comfort perception, with emphasis on their individual characteristics. In this respect, a methodological framework is developed and a preliminary implementation is performed. The main goal of the methodological approach is the consideration of both the classical comfort parameters along with the occupants’ socioeconomic and personalized characteristics that affect their perception and can differentiate their needs even under the same conditions. Among other important findings this preliminary implementation achieved some very promising results, highlighting that occupants’ individual characteristics such as recycling and exercising can affect the occupants’ comfort perception.

Evaluation of Basement's Thermal Performance Against Thermal Comfort Model at Hot-arid Climates, Case Study (Egypt)

Reaching thermal comfort levels in hot-arid climates is becoming more difficult nowadays without the use of high energy consuming mechanical systems. Therefore, the need to use effective passive energy design techniques, such as earth-sheltered buildings, is becoming greater.This paper describes research, that uses monitoring and simulations, to evaluate basements’ thermal performance, which reached thermal comfort levels without active air-conditioning systems, despite the harsh climate conditions. The case study was conducted in Al Minya city, Egypt, which is known for its high diurnal range. The study calibrated a non-conditioned basement simulation model versus the monitored data to simulate its thermal performance. The greatest challenge was to calculate the ground temperature. To do this successfully, we used an iterative approach between packages of the Basement preprocessor and EnergyPlus/Designbuilder until reaching a convergence.The iterative method results showed significant agreement, between the measured and modeled data, with a correlation of 98 percent, and errors with mean bias error and normalized root mean square error of -1.0 and 7.6 percent, respectively. On the other hand, the EnergyPlus method, integrating the Xing approach, showed significantly divergent results between the simulated models versus the measured data. The calibrated model analysis evaluation, using the Fanger’s thermal comfort model, showed satisfactory results within the thermal comfort sensation range.The research results significance indicates that the precise customized detailed iterative method is essential to create the needed inputs which subsequently lead to near-to-actual outputs compared with other ground-contact simulation methods. In fact, the precise customized detailed iterative method approach may be used as a benchmark for simulators for easy and precise ground temperatures’ calculations and earth-sheltered buildings’ simulations.

Evaluation of Basement's Thermal Performance Against Thermal Comfort Model at Hot-arid Climates, Case Study (Egypt)

Reaching thermal comfort levels in hot-arid climates is becoming more difficult nowadays without the use of high energy consuming mechanical systems. Therefore, the need to use effective passive energy design techniques such as earth-sheltered buildings is becoming greater. This paper combines researches that uses monitoring and simulations in order to evaluate basements’ thermal performance that reached thermal comfort levels without active air-conditioning systems, despite the harsh climate conditions. The case study was conducted in Al-Minya city, Egypt, which is known for its high diurnal range. The study calibrated a non-conditioned basement simulation model versus the monitored data to simulate its thermal performance. The greatest challenge was to calculate the ground temperature. To do this successfully, we used an iterative approach between packages of the basement preprocessor and Energy Plus / Design Builder until reaching a convergence. The iterative method results showed significant agreement between the measured and modeled data; with a correlation of 98 percent and errors with mean bias error and normalized root mean square error of -1.0 and 7.6 percent; respectively. On the other hand, the Energy Plus method, integrating the Xing approach, showed significantly divergent results between the simulated models versus the measured data. The calibrated model analysis evaluation, using the Fanger’s thermal comfort model, showed satisfactory results within the thermal comfort sensation range. The research results significance indicates that the precise customized detailed iterative method is essential to create the needed inputs which subsequently lead to near-to-actual outputs compared with other ground-contact simulation methods. In fact, the precise customized detailed iterative method approach may be used as a benchmark for simulators for easy and precise ground temperatures’ calculations and earth-sheltered buildings’ simulations.

New strategy to mitigate urban heat island effect: Energy saving by combining high albedo and low thermal diffusivity in glass ceramic materials

The Global warming is a real problem that attracts great amount of investigations in order to reduce its adverse impact over the planet. The reduction of the heat island effect and the energy consumption into the building areas is an urgent goal. An interesting solution consists in the use of cool roofs, based on high reflective and high emissivity coatings. However, today, some cool roof materials possess some major drawbacks as high solar degradation, decrease of NIR reflection in comparison with the visible reflection and aesthetic restrictions. In order to overcome such limitations, in this work, a tile coated with a new glass ceramic material has been developed in order to improve the solar reflective properties and to reduce its thermal conductivity and increase the specific heat. These three parameters are key to obtain low thermal diffusivity materials to serve as efficient cool roof applications. The increase in solar reflectivity is complimented also by a high reflectivity in the NIR range that results highly convenient for colored materials. These combined properties in addition of increasing the albedo also contributed to improve the thermal comfort sensation inside the buildings. Therefore a great energy saving over 20% is determined in comparison with conventional ceramic tiles. In addition, these materials also offer a structural solution for durable facades and allow a great decorative variability.

An indoor environment evaluation by gender and age using an advanced personalized ventilation system

In a closed space, appropriate thermal comfort and proper indoor air quality are extremely important in order to obtain the optimal work performance and to avoid health problems of the occupants. Using advanced personalized ventilation systems, different comfort needs can be locally satisfied even in case of warm environments. Thermal sensation and the subjective evaluation of indoor air quality of young and elderly people, men and women respectively, were studied in warm environment using advanced personalized ventilation system combined with total volume ventilation system. Using an advanced personalized ventilation system, 20 m3 h−1 air flow was alternately introduced by three air terminal devices built-in the desk and placed on a horizontal plane at the head level of the sitting subject. Thermal sensation was significantly cooler in case of young women in comparison with the other groups. Odor intensity was evaluated to be significantly lower in case of elderly women in comparison with the other groups. Evaluation of air freshness is in correlation with the general thermal sensation. Variation of the direction of the air velocity vector has a cooling side-effect, which, in warm environments, might be useful in order to improve the thermal comfort sensation. Practical application: From the basic factors that influence the thermal comfort sensation, air velocity is the one and only parameter that must be treated as a vector. The air flow velocity has an important effect on the convective heat quantity released by the human body, but the changes in the air velocity direction have a cooling side-effect. This cooling side-effect should be exploited properly in warm environments by advanced personalized ventilation systems to improve the thermal comfort sensation of the occupants without supplementary energy use.

Evaluation of Thermal Sensation in Office Buildings: A Case Study in the Mediterranean

The existing institutional frameworkis expressing, both in Europe and in Greece, the strong drive for improving the existing buildings stock, by means of compulsory measures, as buildings account for almost 40% of the primary energy consumption in Europe. Especially, when referring to office buildings, the existence of increased cooling requirement accounts for very high consumption values (up to 60% of the overall), whilst at the same time the occupants experience significant levels of discomfort. Therefore, the occupants’ well-being as well as their productivity are affected.Within the framework of this study, an evaluation of both thermal comfort and indoor air quality conditions is carried in two office buildings. Both buildings are located in northern Greece and were constructed after 1980 and before 2010, in accordance with the first Greek Thermal Insulating Regulation. In situ measurements were carried during the winter period for the one building and the summer for the other. The measured parameters are the air temperature, the humidity levels and the levels of CO2 emissions specifying the indoor conditions. Furthermore, a revealed preference survey was conducted in order to specify the parameters affecting the occupants’ reaction concerning the indoor thermal conditions through the usage of regression model analysis.The interpretation of occupants’ reaction to indoor conditions and the human's sensation of thermal comfort,based on monitoring the existing environmental conditions and determining probable correlation with individual characteristics are very promising.

Objective and subjective thermal comfort evaluation in Hungary

Thermal comfort sensation can be predicted in the most exact way based on Fanger?s predicted mean vote (PMV) model. This evaluation method takes all the six influencing factors into consideration: air temperature and humidity, air velocity, mean radiant temperature of surrounding surfaces, clothing insulation, and occupants? activities. Fanger?s PMV method was developed for temperate climate and European people, with the participation of university students as subjects. Many researchers had investigated its validity in different geographic locations (i. e. climatic conditions, people) and under non-laboratory circumstances. The results were summarised by van Hoof which had been published in the scientific references. The articles gave us the idea to elaborate the former measurement results. During the last decades thermal comfort was evaluated by our research team using subjective scientific questionnaires and applying the objective Fanger?s model in several office buildings in Hungary. The relation between the PMV and actual mean vote values were analysed based on these results. Investigations were carried out under steady-state conditions in winter time. We performed objective thermal comfort evaluations based on instrumental measurements using the PMV theory. Parallel to this we assessed the subjective thermal sensation using scientific questionnaires. The mathematical relationship between the actual mean vote and PMV was defined according to the evaluated thermal environment: AMV = PMV + 0.275, (arg. ?1.7 ? PMV ? +0.5).

Occupant Comfort and Indoor Temperature Reduction by Using Passive Air Conditioning System with Solar Chimney Concept in Hot Arid Climate

Housing in Egypt consumes high energy for cooling. Bioclimatic building design is one of the strategies of sustainable development. The aim of the present research is to investigate the thermal performance of solar chimney with passive cooling wind tower (SCPC) on occupant’s comfort. The passive cooling design is integrated on the ceiling of 30 m2 test house. Monitoring of indoor environment was carried out over a period of two months in the summer season (September and early October) with a 2 minute interval in order to calculate thermal comfort sensation, Predicted mean vote (PMV) and PPD. The results show that outlet air temperature from the wind tower is 27.3°C. The calculated predicted mean vote (PMV) is within the recommended range (-0.5<PMV<+0.5). This indicates that occupants remain satisfied with indoor thermal environment after using the passive cooling system and the difference is nearly 8 K between outdoor and indoor. The results of this research provide information of the system applicability in the climate of Assiut during day time in order to develop and install on top of real residential buildings in New Assiut, Egypt.

Assessment of thermal comfort of nanosilver-treated functional sportswear fabrics using a dynamic thermal model with human/clothing/environmental factors

The development of nanotechnology has made it possible to add desirable functions to fabrics. Nanosilver has been used to provide antibacterial and odor control functions for sportswear over decades. However, few studies have explored the thermal comfort and ultraviolet (UV) protection properties of nanosilver-treated sportswear fabrics. In this study, a dynamic thermal model was introduced to predict the thermal comfort of nanosilver-treated fabrics for wearers in different environmental conditions. Nanosilver was applied to cotton and polyester knit fabrics and their antibacterial and UV protection properties were evaluated as well. The results indicated that substantial antibacterial and UV protection properties were achieved from nanosilver-treated fabrics. The dynamic thermal model predicted the thermal comfort of the treated fabrics for various human, clothing, and environmental factors. Although there was between two and four times difference in the thermal and evaporative resistance between the two tested fabrics, the predicted thermal comfort sensations were not significantly different in the same human and environmental conditions. From these results, it can be concluded that nanosilver-treated fabrics may provide desirable functionality, while not detracting from thermal comfort. This is one of the first trials in which a dynamic numerical thermal model was used to predict the thermal comfort of nanosilver-treated fabrics for sportswear, taking human, clothing, and environmental conditions into consideration.

Application of a new 13-value thermal comfort scale to moderate environments

A new 13-value thermal comfort scale is adopted in the present study, in order to evaluate the thermal comfort sensation within non-residential buildings with the adaptive approach.18 classrooms located both in Pavia and Perugia, the Fraschini Theatre, and one auditorium located in Pavia were investigated from October 2014 to October 2015 collecting about 1600 questionnaires. All the information reported in the questionnaires was correlated by defining several indexes and a comparative analysis was carried out between the two comfort scales (13-value and 7-value scale).Results showed that using the new 13-value scale the percentage of people who declared a thermal sensation equal to 0 greatly decreased: from 66% to 41% for the classrooms and from 47% to 36% for the theatre-auditorium. The percentage of occupants who considered the environments not thermally comfortable, although they declared a thermal sensation equal to 0, also decreased, from a mean value of 10.4% to 2.7% for the classrooms and from 6.0% to 2.6% for the theatre-auditorium.Considering the 7-value scale, although a thermal sensation equal to 0 was declared, a higher percentage of people who would feel a little bit cooler or a little bit warmer was found. Instead using the 13-value scale, this percentage significantly decreased, because people declared a thermal sensation equal to ±0.5 (more than 50% of cases) instead of 0.In agreement with these results, the new scale seems to be more accurate than the traditional one, allowing a better correlation among all the data reported in the questionnaires.

Evaluasi Kenyamanan Termal Ruang Sekolah SMA Negeri di Kota Padang

This research aims to determine thermal conditions and sensation of thermal comfort in classrooms of high schools in Padang. This study was conducted in 11 State Senior High School (SMA) represented 11 districts in Padang. About 10% of total student body in each schools were participated in this study to vote thermal comfort questioners. To determine thermal comfort level in this study, PMV (Predicted mean Vote) and PPD (Predicted Percentage of dissatisfied) method were used according to standard of thermal comfort in ASHRAE 55-2005 and ISO 7730. PMV method is used to determine scope of situation in the environment that scaled from +3 for very hot until -3 for very cold, and PPD is a method to calculate the number of human (in percentage) dissatisfied with the environment. Calculated PMV and PPD were compared with PMV and PPD resulted from individual vote from questionnaires. Result showed that in general, thermal conditions in classrooms had air temperature and radiant temperature from 27oC – 30oC, air humidity from 68% - 80%, and wind speed of 0 m/s. Calculated PMV from this condition were ranging from +1 slightly warm) until +2 (warm) while PPD calculated greater than 20%. Compared with calculated PMV and PPD values, the individual vote showed values from +0,5 (neutral) until +1 (slightly warm) while PPD values of individual vote greater than 20% except for SMA 2 and SMA 11 Padang. It is concluded that improvements of indoor thermal conditions have to make inside classrooms as well as landscape outside in order to improve thermal comfort level of students during learning and teaching.Keywords: Thermal Comfort, PMV (Predicted Mean Vote), PPD (Predicted Percentage ofDissatisfied), climatic factors, SMA

温罨法が就床中の生体の快適感,体温,皮膚血流量に及ぼす影響

温罨法が就床中の生体の快適感,体温,皮膚血流量に及ぼす影響

A comparison of THI indices leads to a sensible heat-based heat stress index for shaded cattle that aligns temperature and humidity stress.

The combined temperature-humidity heat stress is estimated in farm animals by indices derived of an index based on human thermal comfort sensation. The latter index consists of temperature and humidity measures that sum to form the temperature-humidity index (THI). The hitherto unknown relative contribution of temperature and humidity to the THI was examined. A temperature-humidity data set (temperature 20-42°C and relative humidity 10-70%) was used to assess by regression procedures the relative weights of temperature and humidity in the variance of THI values produced by six commonly used heat stress indices. The temperature (Ta) effect was predominant (0.82-0.95 of variance) and humidity accounted for only 0.05 to 0.12 of THI variance, half of the variance encountered in animal responses to variable humidity heat stress. Significant difference in THI values was found between indices in the relative weights of temperature and humidity. As in THI indices, temperature and humidity are expressed in different physical units, their sum has no physical attributes, and empirical evaluations assess THI relation to animal responses. A sensible heat THI was created, in which at higher temperatures humidity reaches 0.25 of sensible heat, similarly to evaporative heat loss span in heat stressed animals. It relates to ambient temperature-humidity similarly to present THI; its values are similar to other THI but greater at higher humidity. In warm conditions, mean animal responses are similar in both indices. The higher sensitivity to humidity makes this index preferable for warm-humid conditions.

室内空間の温熱的要素の変化と作業難易度の違いが心理生理学的指標に及ぼす影響

Indoor thermal quality affects the conditions of the occupant who is doing tasks in an indoor environment, and also task performance. Therefore, appropriate control of thermal factors is important to improve the conditions of occupant, such as thermal comfort sensation and the arousal level which is related to task performance. In order to determine guidelines how to control the thermal factors for improving the comfort sensation and arousal level, it is necessary to evaluate the condition of occupant by using quantitative and continuously measurable indices such as physiological indices. In this study, we aimed to clarify the relationship between the condition of occupant and physiological indices which is affected by changes in thermal factor and task level. We measured subjective evaluation and physiological indices such as electroencephalogram (EEG), electrocardiogram (ECG), respiration, and skin temperature of 10 participants in 4 experimental conditions consisted of different temperature and arithmetic task level. From the result of time-series analysis and correlation analysis among the experimental conditions, the subjective evaluation value, and physiological indices, it is showed that difference of task level can affect to the correlation between the conditions of occupant and physiological indices. These result suggests that the effect of task level on physiological indices should be considered in order to evaluate the conditions of occupant by using physiological indices.

Analysis of microclimatic diversity and outdoor thermal comfort perceptions in the tropical megacity Dhaka, Bangladesh

The study has observed microclimatic conditions in residential, commercial and educational areas in Dhaka city. Comfort surveys were carried out along with microclimatic measurements. Findings suggest, urban forms that are more variable with irregular plot sizes and building heights, mostly in traditional areas, have positive responses with respect to the synoptic climate, while planned areas with uniform plot sizes and height, shows a tendency to develop daytime urban heat island effect. An east–west orientated street in a formal residential area was found to be 1 °C–3.8 °C warmer than a street in a traditional residential area in the same orientation. It is apparent that the differences are directly linked to the specific geometric pattern of the areas and can be defined by the parameters like uniformity versus diversity and compactness versus openness. Uniform heights, equal building separation and plot sizes can lead to harsher urban microclimate, while variety in these may foster positive changes. Lack of such variety can even affect compact urban areas. This is also evident from the analysis of pedestrian's responses in the case-study areas. Pedestrians in the formal planned areas or less diverse traditional areas were found to be less comfortable than those in the more variable areas. A statistical analysis of climatic variables and thermal sensation showed moderately strong and significant correlations. These reveal that urban geometry and the resultant climatic variables may not be the only, but one of the most important factors for governing the outdoor thermal comfort sensation in a tropical climate.

Heating Performance and Occupants′ Comfort Sensation of Low temperature Radiant Floor Heating System in Apartment Buildings of Korea

AbstrctTo develop an energy-efficient low-temperature radiant floor heating system in an apartment housing unit from an improved the overall heating system efficiency perspective, it is essential to consider the occupants′ thermal comfort and evaluate the thermal environment and thermal output of the radiant panel. This study evaluated the heating performance of a low temperature radiant floor heating system by monitoring the water flow rates, supply and return water temperatures, indoor room temperatures and floor surface temperatures through field measurements, and surveyed the occupants′ thermal comfort through questionnaires. Based on the results of field measurements and the occupants′ questionnaires, the heating performance and thermal comfort sensation of a low-temperature radiant floor heating system were analyzed. The design considerations of a low temperature radiant floor heating system are suggested.

Thermal comfort assessment of a surgical room through computational fluid dynamics using local PMV index.

Studies concerning indoor thermal conditions are very important in defining the satisfactory comfort range in health care facilities. This study focuses on the evaluation of the thermal comfort sensation felt by surgeons and nurses, in an orthopaedic surgical room of a Portuguese hospital. Two cases are assessed, with and without the presence of a person. Computational fluid dynamic (CFD) tools were applied for evaluating the predicted mean vote (PMV) index locally. Using average ventilation values to calculate the PMV index does not provide a correct and enough descriptive evaluation of the surgical room thermal environment. As studied for both cases, surgeons feel the environment slightly hotter than nurses. The nurses feel a slightly cold sensation under the air supply diffuser and their neutral comfort zone is located in the air stagnation zones close to the walls, while the surgeons feel the opposite. It was observed that the presence of a person in the room leads to an increase of the PMV index for surgeons and nurses. That goes in line with the empirical knowledge that more persons in a room lead to an increased heat sensation. The clothing used by both classes, as well as the ventilation conditions, should be revised accordingly to the amount of persons in the room and the type of activity performed.