scholarly journals Does a neutral thermal sensation determine thermal comfort?

2018 ◽  
Vol 39 (2) ◽  
pp. 183-195 ◽  
Author(s):  
Sally Shahzad ◽  
John Brennan ◽  
Dimitris Theodossopoulos ◽  
John K Calautit ◽  
Ben R Hughes
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Building Design ◽  
Thermal Preference ◽  
Practical Application ◽  
Comfort Zone ◽  
Indoor Thermal Environment ◽  
Human Thermal Comfort ◽  
Comfort Condition

The neutral thermal sensation (neither cold, nor hot) is widely used through the application of the ASHRAE seven-point thermal sensation scale to assess thermal comfort. This study investigated the application of the neutral thermal sensation and it questions the reliability of any study that solely relies on neutral thermal sensation. Although thermal-neutrality has already been questioned, still most thermal comfort studies only use this measure to assess thermal comfort of the occupants. In this study, the connection of the occupant’s thermal comfort with thermal-neutrality was investigated in two separate contexts of Norwegian and British offices. Overall, the thermal environment of four office buildings was evaluated and 313 responses (three times a day) to thermal sensation, thermal preference, comfort, and satisfaction were recorded. The results suggested that 36% of the occupants did not want to feel neutral and they considered thermal sensations other than neutral as their comfort condition. Also, in order to feel comfortable, respondents reported wanting to feel different thermal sensations at different times of the day suggesting that occupant desire for thermal comfort conditions may not be as steady as anticipated. This study recommends that other measures are required to assess human thermal comfort, such as thermal preference. Practical application: This study questions the application of neutral thermal sensation as the measure of thermal comfort. The findings indicate that occupant may consider other sensations than neutral as comfortable. This finding directly questions the standard comfort zone (e.g. ASHRAE Standard 55) as well as the optimum temperature, as many occupants required different thermal sensations at different times of the day to feel comfortable. These findings suggest that a steady indoor thermal environment does not guarantee thermal comfort and variations in the room temperature, which can be controlled by the occupant, need to be considered as part of the building design.

scholarly journals Impact of ventilation system type on indoor thermal environment and human thermal comfort in a ceiling cooling room

2021 ◽  
pp. 277-277
Author(s):  
Xiaozhou Wu ◽  
Genglin Liu ◽  
Jie Gao ◽  
Shuang Wu
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Ventilation System ◽  
Physical Parameters ◽  
Curtain Wall ◽  
Indoor Thermal Environment ◽  
Human Thermal Comfort ◽  
System Type

A ceiling cooling (CC) system integrated with a mechanical ventilation system is an advanced HVAC system for the modern office building with glass curtain wall. In this paper, considering the influence of heat transfer of external envelope, the indoor thermal environment and human thermal comfort were objectively measured and subjectively evaluated in a ceiling cooling room with mixing ventilation (MV) or underfloor air distribution (UFAD). Indoor physical parameters and human skin temperatures were measured as the chilled ceiling surface temperature and supply air temperature were 17.1?C-17.6?C and 22.2?C - 22.6?C. Simultaneously, 16 subjects (8 males and 8 females) were selected to subjectively evaluate the thermal environment. The results showed that the difference between mean radiant temperature and air temperature in the occupied zone was 0.8?C with CC+MV and 1.2?C with CC+UFAD, and the indoor air velocity was 0.17m/s with CC+MV and 0.13m/s with CC+UFAD. In addition, the calculated and measured thermal sensation votes with CC+MV were all slightly less than those with CC+UFAD. Therefore, ventilation system type had a slight impact on the indoor thermal environment and human thermal comfort in the ceiling cooling room.

Indoor Thermal Environment Test and Investigation Analysis—Based on Newly-Built Residential Houses in Daping Village, Sichuan Province

2011 ◽  
Vol 368-373 ◽  
pp. 3667-3671
Author(s):  
Hui Cheng ◽  
Jia Ping Liu ◽  
Da Long Liu ◽  
Fang Wei Tang ◽  
Yun Gang An
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Building Design ◽  
Sichuan Province ◽  
Objective Test ◽  
Environment Design ◽  
Residential Housing ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Housing Environment

Based on the recognition of original defective residential housing environment in Daping village, constructional measures were improved and updated. Objective test and subjective investigation on indoor thermal comfort were carried out and analyzed in the typically new and old residential houses to propose measures for further improvements. This paper aims to summarize experience and deficiencies in aspects of indoor thermal environment design and to provide reference to building design after disasters in future.

Field Survey on Occupant Thermal Comfort of Cold Regions in Transition Season

2013 ◽  
Vol 805-806 ◽  
pp. 1620-1624 ◽  
Author(s):  
Wan Ying Qu
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Indoor Air ◽  
Field Survey ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Residential Buildings ◽  
Cold Regions ◽  
Indoor Thermal Environment ◽  
Transition Season

A thermal comfort field study was investigated in residential buildings of cold regions in transition season during which the indoor thermal environment conditions are measured, the thermal sensation value of the occupants is questioned and recorded. A seven-point thermal sensation scale was used to evaluate the thermal sensation. The statistical method was used to analyze the data and the conclusions are as follows in transition season: clothing increase in 0.1clo when the indoor air temperature is lowered by 1°C; and clothing will be a corresponding increase in 0.06clo when the outdoor air temperature is lowered by 1°C; clothing also varies with gender, age, weight and thermal history and other related; the measured thermal neutral temperature is 21.3°C; and the minimum accepted temperature is 11.4 °C in transition season in cold regions. Most people choose to change clothes, switch and other passive measures, and occasionally take active measures of heater, electric fans and others.

A study on the heat dissipation and thermal environment of a novel heated bed

2018 ◽  
Vol 42 (5) ◽  
pp. 629-651 ◽  
Author(s):  
Dengjia Wang ◽  
Xiaowen Wang ◽  
Yanfeng Liu ◽  
Penghao Chen ◽  
Jiaping Liu
Keyword(s):  
Thermal Comfort ◽  
Heat Dissipation ◽  
Thermal Environment ◽  
Process Analysis ◽  
District Heating ◽  
Heat Transfer Process ◽  
Time Sharing ◽  
Indoor Thermal Environment ◽  
Human Thermal Comfort ◽  
Heating Energy Consumption

This study proposes a novel heated bed that can heat the whole room in the daytime and heat the surroundings of the bed at night. The conditions of conversion between the daytime and nighttime are achieved by the opening and closing of the fan and vents. The simplified calculation method of heat dissipation of the bed was obtained via the flow and heat transfer process analysis in two heating modes. Numerical simulations of heat dissipation and indoor thermal environment under different conditions in the daytime and nighttime were performed using computational fluid dynamics (CFD) to master the indoor temperature distribution characteristics. The simulation results were compared with the experimental results and show good agreement. The results show that the maximum of heat dissipation can reach 1300 W in the daytime and the indoor thermal environment can meet the human thermal comfort requirement. At night, the bed can create a high-temperature circle around it, which can ensure the sleep thermal comfort of the human body at a cooler indoor thermal environment, whose temperature can be 5°C lower than normal conditions. The heated bed can achieve the time-sharing district heating of room and reduce the heating energy consumption significantly. This study can provide the design and selection basis for the heated bed.

scholarly journals Thermal environment assessment in selected Polish educational buildings

2021 ◽  
Vol 246 ◽  
pp. 15004
Author(s):  
Luiza Dębska ◽  
Justyna Krakowiak
Keyword(s):  
Indoor Air ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Subjective Assessment ◽  
Thermal Preference ◽  
Air Velocity ◽  
Indoor Thermal Environment ◽  
Environment Assessment ◽  
Educational Buildings ◽  
The City

The paper presents experimental results of a study on indoor thermal environment in selected educational buildings located in the city of Kielce (Poland). The volunteers in the investigated rooms were asked to fill in the anonymous questionnaires containing questions on their thermal sensation, thermal preference and thermal acceptability votes as well as humidity assessment and humidity preference votes. In total, 83 people completed the questionnaires. Simultaneously, the indoor air parameters were measured with a microlimate meter equipped with precision sensors to measure air and globe temperatures, air velocity and relative humidity. The analysis of the obtained results provides information on the subjective assessment of the thermal environment in the considered rooms. It allowed to assess whether the guidelines given in the standard are consistent with the real feeling of comfort of the respondents. Research in the performed scope has shown that the feelings of the respondents and the standard guidelines diverge. It was noticed that that the subjects definitely felt better in the rooms where the temperature was around 22.5°C. The subjects felt worse at the temperature of 25.3°C and the worst of 27.6°C.

scholarly journals Perceived Thermal Environment of NaturallyVentilated Classrooms in India

2016 ◽  
Vol 3 (2) ◽  
pp. 149-165
Author(s):  
Ramprasad Vittal ◽  
Subbaiyan Gnanasambandam
Keyword(s):  
Regression Analysis ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Thermal Preference ◽  
Comfort Zone ◽  
Neutral Temperature ◽  
Adaptive Comfort ◽  
Cross Tabulation ◽  
Institute Of Technology ◽  
Lower Temperature

A ield study of thermal environment in naturally ventilated classrooms was conducted in the Department of Architecture at the National Institute of Technology, Tiruchirappalli, India. The study included 176 architecture students and was conducted over ive days during the comparatively cool months of December and January. The results show that 82% of participants voted for ‘comfortable’ on the thermal sensation scale. Cross tabulation of thermal sensation and thermal preference shows that 50% of those who voted within the ‘neutral’ thermal sensation range preferred cooler temperatures and 43% wanted no change. Classroom temperature was acceptable to 85% of students and unacceptable to 15% of students. Perceived thermal sensation tends toward the cool side (mean -0.26). Regression analysis yielded a comfort zone (voting within -1 and +1) of 26.9–30.8 °C, with neutral temperature of 29.0 °C. Standard adaptive comfort models yielded lower temperature than ield indings.

The Study of Indoor Thermal Environment Characteristics of Office Building Effected by Stratum Ventilation

2014 ◽  
Vol 556-562 ◽  
pp. 803-806
Author(s):  
Ze Qin Liu ◽  
Zhen Jun Zuo ◽  
Tai Shun Liu
Keyword(s):  
Thermal Comfort ◽  
Thermal Stratification ◽  
Thermal Environment ◽  
Vertical Direction ◽  
Ventilation Rate ◽  
Office Building ◽  
Breathing Zone ◽  
Indoor Thermal Environment ◽  
Human Thermal Comfort ◽  
Air Supply

A typical office building with stratum ventilation as the research object was studied in this paper. CFX Fluid Computation software was used to numerical simulate the characteristics of indoor thermal environment effected by air speeds under 19°C supply air temperature and 8 ventilation rate. The numerical simulate results showed that, the obvious thermal stratification occurred in the vertical direction. Such thermal stratification met the demands of building energy conservation and the human thermal comfort. In this paper, the velocity coefficient and the temperature coefficient were used to evaluate thermal comfort. From the results of the numerical simulation, it could be seen that when the supply air speeds were controlled between 0.5m/s to 0.9m/s, the thermal comfort, as well as the air supply efficiency in the human activity area was relative satisfactory. With the constant fresh air ventilated to the breathing zone, the air quality could be improved.

Evaluation of Human Thermal Comfort Using Near-Infrared Spectroscopy

2014 ◽  
Author(s):  
Keiichi Watanuki ◽  
Lei Hou ◽  
Yuuki Kondou
Keyword(s):  
Energy Consumption ◽  
Thermal Comfort ◽  
Air Conditioning ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Brain Activation ◽  
Indoor Temperature ◽  
Prefrontal Area ◽  
Human Thermal Comfort ◽  
Conditioning Control

Air-conditioning equipment is used in various places such as houses, office buildings, and public facilities and is indispensable in modern-day life. Therefore, the energy consumption of air-conditioning equipment accounts for a large percentage of the total energy consumption in the average household. Specifically, it accounts for 26% of the annual energy consumption in ordinary homes and 27% in industry, according to the Annual Energy Report for Japan, which was presented by the Ministry of the Economy, Trade, and Industry, and the Agency for Natural Resources and Energy in 2010. Therefore, it is desirable to reduce energy consumption by reducing the air-conditioning load. The Ministry of the Environment recommends a constant preset temperature of 28°C in summer to decrease energy consumption. However, many people feel uncomfortable in such a thermal environment. Thus, an air-conditioning control to simultaneously suppress energy consumption and maintain human thermal comfort is desired. To develop such a control, an index to accurately evaluate human thermal comfort is needed. When a person feels comfortable or uncomfortable, their prefrontal area, which is involved in thinking and the feeling of emotions, is activated. It is presumed that the measurement of the brain activation reaction of a person will reveal whether the person feels comfortable or uncomfortable in the thermal environment. The evaluation of thermal comfort by means of brain activation reactions will allow one to develop the optimum air-conditioning control to maintain human thermal comfort. This paper proposes a method to evaluate thermal comfort via brain signals and ultimately aims to develop an air-conditioning control system utilizing this evaluation method. This paper will describe the measurement procedure of brain activation reactions to indoor-temperature change by using near-infrared spectroscopy and the relationship between thermal comfort and brain activation reaction. This study also investigated the changes in oxyHb levels together with indoor-temperature changes, measured with the NIRS. We measured the changes in the oxyHb levels of the prefrontal area when the temperature increased and decreased. As a result, the oxyHb level in the prefrontal area correlated with the indoor-temperature change, the PMV, and the subjects’ declaration of thermal sensation. Conversely, the change in the oxyHb level with the inclusion of wind and a constant indoor temperature significantly differed with that with a varying indoor temperature. Furthermore, the oxyHb change correlated with the PMV and the subject’s declaration of thermal sensation. Therefore, the measured oxyHb change may represent the thermal comfort of a person.

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