scholarly journals Analyzing the Time-Varying Thermal Perception of Students in Classrooms and Its Influencing Factors from a Case Study in Xi’an, China

Buildings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 75
Author(s):  
Yongkai Sun ◽  
Xi Luo ◽  
Hui Ming
Keyword(s):  
Influencing Factors ◽  
Energy Savings ◽  
Thermal Sensation ◽  
Activity Levels ◽  
Time Varying ◽  
Thermal Perception ◽  
Temperature Changes ◽  
Spatial Environment ◽  
Activity State ◽  
Questionnaire Surveys

Owing to movement in the spatial environment and changes in activity levels, students’ thermal perception is time varying in classrooms throughout different periods of the day. However, previous studies have rarely considered the time-varying thermal perception in different periods of the day, which may cause discomfort for students and lead to energy wastage. Therefore, a study was conducted to investigate the time-varying thermal perception of students and its influencing factors in different classes of the day. In addition, the differences in students’ adaptive behaviors in different periods were also explored. A total of 578 university students were surveyed using questionnaire surveys during the heating season in Xi’an, China. The following results can be obtained: (1) The thermal sensation vote and thermal preference vote values in the afternoon were significantly higher than those in the morning. At the start of the first class in the morning/afternoon, the thermal sensation of the students had the highest sensitivity to outdoor temperature changes. (2) The students’ thermal perception was greatly affected by the preclass activity state at the start of the first class in the morning/afternoon. However, in other periods, the above phenomenon was not obvious. (3) In the afternoon, the frequency of clothing adjustment was greater than that in the morning, and this behavior would significantly affect the students’ thermal sensation. (4) Compared with the current classroom heating strategy, the heating strategy of dynamically adjusting the indoor set temperature according to the time-varying characteristics of the students can theoretically achieve energy savings of 25.6%.

Some evidence of a time-varying thermal perception

2021 ◽  
pp. 1420326X2110345
Author(s):  
Marika Vellei ◽  
William O’Brien ◽  
Simon Martinez ◽  
Jérôme Le Dréau
Keyword(s):  
Thermal Comfort ◽  
Energy Savings ◽  
Thermal Environment ◽  
Thermal Conditions ◽  
Time Of Day ◽  
Time Varying ◽  
Thermal Perception ◽  
Indoor Thermal Environment ◽  
Human Circadian Rhythm ◽  
Comfort Criteria

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.

scholarly journals Hue-Heat Hypothesis: A Step forward for a Holistic Approach to IEQ

2019 ◽  
Vol 111 ◽  
pp. 02038 ◽  
Author(s):  
Francesca Romana d’Ambrosio Alfano ◽  
Laura Bellia ◽  
Francesca Fragliasso ◽  
Boris Igor Palella ◽  
Giuseppe Riccio
Keyword(s):  
Thermal Comfort ◽  
Energy Savings ◽  
Thermal Sensation ◽  
Holistic Approach ◽  
Spectral Irradiance ◽  
Light Sources ◽  
Thermal Perception ◽  
General Increase ◽  
Neutral Conditions ◽  
Stimulation Of

For many years different human factors contributing to the IEQ have been studied separately. Concerning thermal perception, despite it is almost accepted that thermal comfort can be influenced by concomitant stimulation of non-tactile modalities, relatively few investigations have succeeded in delineating non-tactile stimulations as the visual ones. The hue-heat hypothesis is based on the idea that, when spectral irradiance pattern at the observer’s eye shows a great amount of short wavelengths, the space is perceived as cooler. Conversely, when long wavelengths are predominant, the space is perceived as warmer. This means that operating on light characteristics could help in improving thermal comfort for the occupants with possible energy savings obtained by acting on the set-point temperature of HVAC systems. To verify this hypothesis, this paper will deal with a subjective investigation carried out in a special mechanically conditioned test room equipped with white-tuning LED sources. Investigated subjects have been exposed to two different light scenes consisting of warm (3000 K) and cool light sources (6000 K) at a fixed task illuminance value. Preliminary results seem to demonstrate that cool light is effective in shifting to cool the perceived thermal sensation with a general increase of people under neutral conditions.

scholarly journals Comparison of Invasive Apple Snail (Pomacea canaliculata) Behaviors in Different Water Temperature Gradients

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1149
Author(s):  
Mi-Jung Bae ◽  
Eui-Jin Kim ◽  
Young-Seuk Park
Keyword(s):  
Water Temperature ◽  
Farming Systems ◽  
Freshwater Snail ◽  
Freshwater Ecosystems ◽  
Pomacea Canaliculata ◽  
Activity Levels ◽  
Self Organizing Map ◽  
Apple Snail ◽  
Temperature Changes ◽  
Organic Farming Systems

Pomacea canaliculata (known as invasive apple snail) is a freshwater snail native to South America that was introduced into many countries (including Asia and North America) as a food source or for organic farming systems. However, it has invaded freshwater ecosystems and become a serious agricultural pest in paddy fields. Water temperature is an important factor determining behavior and successful establishment in new areas. We examined the behavioral responses of P. canaliculata with water temperature changes from 25 °C to 30 °C, 20 °C, and 15 °C by quantifying changes in nine behaviors. At the acclimated temperature (25 °C), the mobility of P. canaliculata was low during the day, but high at night. Clinging behavior increased as the water temperature decreased from 25 °C to 20 °C or 15 °C. Conversely, ventilation and food consumption increased when the water temperature increased from 25 °C to 30 °C. A self-organizing map (an unsupervised artificial neural network) was used to classify the behavioral patterns into seven clusters at different water temperatures. These results suggest that the activity levels or certain behaviors of P. canaliculata vary with the water temperature conditions. Understanding the thermal biology of P. canaliculata may be crucial for managing this invasive snail.

Research on influencing factors and time-varying model of thermal conductivity of concrete at early age

2021 ◽  
pp. 125638
Author(s):  
Jinpeng Dai ◽  
Qicai Wang ◽  
Ruixiao Bi ◽  
Chong Wang ◽  
Zhuowei Han ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Influencing Factors ◽  
Early Age ◽  
Time Varying

scholarly journals Assessing the indoor thermal comfort of a toll station

2019 ◽  
Vol 282 ◽  
pp. 02031
Author(s):  
Ricardo M.S.F. Almeida ◽  
Eva Barreira ◽  
Sandra Soares ◽  
Ramos Nuno M.M. ◽  
Sérgio Lopes ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Indoor Environment ◽  
Thermal Sensation ◽  
Physical Parameters ◽  
Indoor Environmental Quality ◽  
Thermal Perception ◽  
Health And Wellbeing ◽  
Local Thermal Comfort ◽  
Toll Station ◽  
Global And Local

The importance of a good indoor environment for peoples’ health and wellbeing is nowadays clearly established. Besides enhancing the wellbeing of building occupants and helping decrease the occurrence of building related illness, a good indoor environment can also lead to a decrease in worker complaints and absenteeism. This paper presents the results of a three-month monitoring campaign where the thermal comfort of a toll station was evaluated, including the main room and the cabins. The physical parameters required for the assessment of both global and local thermal comfort were measured and the results were compared with the thermal perception of the occupants, which was collected through questionnaires. The indoor environmental quality in the main room was better than in the cabins and a mismatch between the PMV index and the occupants thermal sensation was identified.

Presentation of Rapid Temperature Change Using Spatially Divided Hot and Cold Stimuli

2013 ◽  
Vol 25 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Katsunari Sato ◽  
◽  
Takashi Maeno
Keyword(s):  
Temperature Change ◽  
Thermal Sensation ◽  
Spatial Summation ◽  
Single Stimulus ◽  
Experimental Results ◽  
Thermal Perception ◽  
Rapid Temperature ◽  
Temperature Sense ◽  
Thermal Stimuli

We propose a thermal display that presents a rapid temperature change using spatially divided hot and cold stimuli. The display exploits two characteristics of human thermal perception: spatial summation and the adapting temperature. Experimental results confirmed that users perceived separate individual thermal stimuli as a single stimulus because of spatial summation. Our thermal display successfully made the skin simultaneously more sensitive to both hot and cold stimuli by using spatially divided hot and cold stimuli, each of which separately adjusts the adapting temperature so that it enables users to perceive thermal sensation rapidly. The thermal display that we fabricated enabled users to perceive a different temperature sense by changing the temperature of hot and cold stimuli.

scholarly journals Users’ Sensations in the Context of Energy Efficiency Maintenance in Public Utility Buildings

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8159
Author(s):  
Edyta Dudkiewicz ◽  
Marta Laska ◽  
Natalia Fidorów-Kaprawy
Keyword(s):  
Energy Efficiency ◽  
Relative Humidity ◽  
Thermal Sensation ◽  
Co2 Concentration ◽  
Public Utility ◽  
Temperature Changes ◽  
The Public ◽  
Air Movement ◽  
Indoor Conditions ◽  
The Relationship

Research towards understanding the relationship between maintaining thermal comfort and energy efficiency in the public utility buildings was undertaken among 323 1st year students during class hours. Questionnaires surveys and measurements of indoor conditions were performed. The article identified students’ sensations and perceptions concerning indoor conditions. Temperature, relative humidity, air velocity and CO2 concentration measured to assess room conditions showed that the auditorium had almost comfortable conditions according to the literature guidelines. The indices used to assess students’ perceptions were: Thermal Sensation Vote (TSV), Thermal Preference Vote (TPV), Air Freshness Sensation Vote (AfSV), Air Movement Preference Vote (AmPV), and Relative Humidity Preference Vote (RHPV). The interpretation of these indicators showed that while the students’ requests for temperature changes and increased air movement are adequate for the air conditions in the room, the evaluation of stuffiness and requests for changes in humidity levels are surprising. Striving uncritically to meet the desired room parameters, according to the users votes, can lead to deterioration of the air and not only the increase in energy consumption but even waste it. Better understanding of users’ preferences and behaviour and further application of this knowledge indirectly aim at increasing energy efficiency in buildings.

scholarly journals Estimation of Thermal Performance and Heat Loss in Plastic Greenhouses with and without Thermal Curtains

Energies ◽  
2018 ◽  
Vol 11 (3) ◽  
pp. 578 ◽  
Author(s):  
Hyung-Kweon Kim ◽  
Geum-Choon Kang ◽  
Jong-Pil Moon ◽  
Tae-Seok Lee ◽  
Sung-Sik Oh
Keyword(s):  
Surface Temperature ◽  
Energy Savings ◽  
Transfer Coefficients ◽  
Temperature Changes ◽  
Heat Transfer Coefficients ◽  
U Value ◽  
Outer Cover ◽  
Heating Energy Consumption ◽  
Insulation Performance ◽  
Indoor And Outdoor

Greenhouses are important for stable food production, but require large amounts of energy to maintain their microclimate in regions with harsh climates. This study assessed the internal thermal insulation performance of thermal curtains in double-layered plastic greenhouses in Korea in winter using cover surface temperature changes and heat transfer coefficients (U values). The thermal curtain performance increased as the temperatures of the inner cover surface increased and the outer cover surface decreased. The outer cover surface temperature with thermal curtains was almost uniformly 1.9 °C lower than that without thermal curtains, whereas the inner cover surface temperature was higher, demonstrating the warming effect of thermal curtain use. Under a constant indoor and outdoor air temperature difference, the daily average heating energy consumption was directly proportional to the U value. The U values were 2.76 W m−2 °C−1 with thermal curtains and 3.85 W m−2 °C−1 without thermal curtains. In double-layered plastic greenhouses that were covered with 0.1-mm-thick polyethylene, incorporating thermal curtains at night resulted in energy savings of about 28.7%, which was related to the decrease in U values. Installing and using thermal curtains at night in winter is a highly economical method for heating savings. These results can be used to promote energy savings in greenhouses in harsh climates.

Subjective Evaluation of Thermal Comfort Using an Air Recirculation Device

1983 ◽  
Vol 27 (8) ◽  
pp. 751-756
Author(s):  
David A. VanDyke ◽  
Frederick H. Rohles ◽  
Michael P. Webster
Keyword(s):  
Thermal Comfort ◽  
Energy Demand ◽  
Energy Savings ◽  
Rating Scale ◽  
Thermal Sensation ◽  
Subjective Evaluation ◽  
Comfort Level ◽  
National Bureau ◽  
Environmental Laboratory ◽  
Fan Speed

To determine the effectiveness of a small fan in enhancing thermal comfort in an open office, eight subjects were studied at 24.4 C (76F), 26.1 C (79F), and 27.8 C (82F) (all at 50% RH), in an environmental laboratory where each workstation was equipped with a small variable speed fan. Control trials were run at all three temperatures without the use of the fan. Three subjective responses were measured: thermal sensation (a nine category rating scale), thermal comfort (a seven pair semantic differential scale), and temperature preference. During fan tests, subjects were allowed to adjust the fan speed to their preference at 15 minute intervals. Results showed that use of the fan could allow a 3°F temperature increase while maintaining the same comfort level, or increase comfort at temperatures of 79°F and up. The 3°F increase in temperature would result in a 9% energy savings, based on the National Bureau of Standards suggestion of a reduction in air conditioning energy demand of 6% per °C or 3% per °F. The study also shows that users prefer a fan that is adjustable in speed and placement.

scholarly journals Review on the HVAC System Modeling Types and the Shortcomings of Their Application

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Raad Z. Homod
Keyword(s):  
Large Scale ◽  
Energy Savings ◽  
Thermal Sensation ◽  
System Modeling ◽  
Thermal Inertia ◽  
Hvac System ◽  
Advantages And Disadvantages ◽  
Building Models ◽  
Hvac System Modeling ◽  
High Thermal Inertia

The modeling of the heating, ventilation, and air conditioning (HVAC) system is a prominent topic because of its relationship with energy savings and environmental, economical, and technological issues. The modeling of the HVAC system is concerned with the indoor thermal sensation, which is related to the modeling of building, air handling unit (AHU) equipments, and indoor thermal processes. Until now, many HVAC system modeling approaches are made available, and the techniques have become quite mature. But there are some shortcomings in application and integration methods for the different types of the HVAC model. The application and integration processes will act to accumulate the defective characteristics for both AHU equipments and building models such as nonlinear, pure lag time, high thermal inertia, uncertain disturbance factors, large-scale systems, and constraints. This paper shows types of the HVAC model and the advantages and disadvantages for each application of them, and it finds out that the gray-box type is the best one to represent the indoor thermal comfort. But its application fails at the integration method where its response deviated to unreal behavior.

Sign in / Sign up

Export Citation Format

Share Document