Relationship between Human Thermal Comfort and Indoor Thermal Environment Parameters in Various Climatic Regions of China

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.

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

Thermal Science ◽

10.2298/tsci210108277w ◽

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.

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Does a neutral thermal sensation determine thermal comfort?

Building Services Engineering Research and Technology ◽

10.1177/0143624418754498 ◽

2018 ◽

Vol 39 (2) ◽

pp. 183-195 ◽

Cited By ~ 16

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.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.803 ◽

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.

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Draught Rate Assessment in a Ventilated Classroom Based on Eight Hours Long Monitoring of Indoor Thermal Environment Parameters

2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA) ◽

10.1109/efea49713.2021.9406257 ◽

2021 ◽

Author(s):

Detelin Markov ◽

Peter Stankov ◽

Iskra Simova ◽

Rositsa Velichkova ◽

Radostina A. Angelova ◽

...

Keyword(s):

Thermal Environment ◽

Indoor Thermal Environment ◽

Environment Parameters

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A Field Study on the Indoor Thermal Environment of the Airport Terminal in Tibet Plateau in Winter

Journal of Engineering ◽

10.1155/2017/7196184 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Jianglong Zhen ◽

Jun Lu ◽

Guangqin Huang ◽

Liyue Zeng ◽

Jianping Lin ◽

...

Keyword(s):

Relative Humidity ◽

Thermal Environment ◽

Vertical Direction ◽

Outer Zone ◽

Tibet Plateau ◽

Indoor Thermal Environment ◽

Airport Terminal ◽

Globe Temperature ◽

Environment Parameters ◽

Radiant Floor Heating

In order to study the characteristics of indoor thermal environment in the airport terminal in Tibet Plateau with radiant floor heating in winter, a field measurement of the indoor thermal environment was conducted in Lhasa Gonggar Airport terminal 2. First, the unique climate characteristics in Tibet Plateau were analyzed through comparison of meteorological parameters in Beijing and Lahsa. The thermal environment in the terminal was divided into outer zone and inner zone as well as south zone and north zone. Thermal environment parameters including air temperature, black globe temperature, relative humidity in each zone, and inner surface temperature of envelope were measured and analyzed. Meanwhile, temperature and relative humidity in the vertical direction were measured. In addition, PMV and PPD were calculated for evaluating the thermal environment in the terminal. The findings can provide guidance for the design and regulation of thermal environment in terminals in Tibet Plateau in China.

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Towards Sustainable Development: Building’s Retrofitting with PCMs to Enhance the Indoor Thermal Comfort in Tropical Climate, Malaysia

Sustainability ◽

10.3390/su13073614 ◽

2021 ◽

Vol 13 (7) ◽

pp. 3614

Author(s):

Zeyad Amin Al-Absi ◽

Mohd Isa Mohd Hafizal ◽

Mazran Ismail ◽

Azhar Ghazali

Keyword(s):

Climate Change ◽

Sustainable Development ◽

Thermal Comfort ◽

Phase Change Materials ◽

Thermal Environment ◽

High Energy ◽

Transition Temperatures ◽

Indoor Thermal Environment ◽

Adaptive Thermal Comfort ◽

The Difference

Building sector is associated with high energy consumption and greenhouse gas emissions, which contribute to climate change. Sustainable development emphasizes any actions to reduce climate change and its effect. In Malaysia, half of the energy utilized in buildings goes towards building cooling. Thermal comfort studies and adaptive thermal comfort models reflect the high comfort temperatures for Malaysians in naturally conditioned buildings, which make it possible to tackle the difference between buildings’ indoor temperature and the required comfort temperature by using proper passive measures. This study investigates the effectiveness of building’s retrofitting with phase change materials (PCMs) as a passive cooling technology to improve the indoor thermal environment for more comfortable conditions. PCM sheets were numerically investigated below the internal finishing of the walls. The investigation involved an optimization study for the PCMs transition temperatures and quantities. The results showed significant improvement in the indoor thermal environment, especially when using lower transition temperatures and higher quantities of PCMs. Therefore, the monthly thermal discomfort time has decreased completely, while the thermal comfort time has increased to as high as 98%. The PCM was effective year-round and the optimum performance for the investigated conditions was achieved when using 18mm layer of PCM27-26.

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Energy-saving potential of intermittent heating system: Influence of composite phase change wall and optimization strategy

Energy Exploration & Exploitation ◽

10.1177/0144598720969217 ◽

2020 ◽

pp. 014459872096921

Author(s):

Yanru Li ◽

Enshen Long ◽

Lili Zhang ◽

Xiangyu Dong ◽

Suo Wang

Keyword(s):

Energy Consumption ◽

Thermal Comfort ◽

Phase Change ◽

Air Temperature ◽

Indoor Air ◽

Thermal Environment ◽

Optimization Strategy ◽

Indoor Thermal Environment ◽

Indoor Thermal Comfort ◽

Intermittent Heating

In the Yangtze River zone of China, the heating operation in buildings is mainly part-time and part-space, which could affect the indoor thermal comfort while making the thermal process of building envelope different. This paper proposed to integrate phase change material (PCM) to building walls to increase the indoor thermal comfort and attenuate the temperature fluctuations during intermittent heating. The aim of this study is to investigate the influence of this kind of composite phase change wall (composite-PCW) on the indoor thermal environment and energy consumption of intermittent heating, and further develop an optimization strategy of intermittent heating operation by using EnergyPlus simulation. Results show that the indoor air temperature of the building with the composite-PCW was 2–3°C higher than the building with the reference wall (normal foamed concrete wall) during the heating-off process. Moreover, the indoor air temperature was higher than 18°C and the mean radiation temperature was above 20°C in the first 1 h after stopping heating. Under the optimized operation condition of turning off the heating device 1 h in advance, the heat release process of the composite-PCW to the indoor environment could maintain the indoor thermal environment within the comfortable range effectively. The composite-PCW could decrease 4.74% of the yearly heating energy consumption compared with the reference wall. The optimization described can provide useful information and guidance for the energy saving of intermittently heated buildings.

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Some evidence of a time-varying thermal perception

Indoor and Built Environment ◽

10.1177/1420326x211034563 ◽

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.

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Importance of Behavioral Adjustments for Adaptive Thermal Comfort in a Condominium with HEMS System

Journal of the Institute of Engineering ◽

10.3126/jie.v15i3.32175 ◽

2020 ◽

Vol 15 (3) ◽

pp. 163-170

Author(s):

Rajan KC ◽

Hom Bahadur Rijal ◽

Masanori Shukuya ◽

Kazui Yoshida

Keyword(s):

Thermal Comfort ◽

Air Temperature ◽

Energy Use ◽

Thermal Environment ◽

Residential Buildings ◽

Outdoor Environment ◽

Adaptive Behaviors ◽

Outdoor Air ◽

Indoor Thermal Environment ◽

Indoor Thermal Comfort

The energy use in residential dwellings has been increasing due to increasing use of modern electric appliances to make the lifestyle easier, entertaining and better. One of the major purposes of indoor energy use is for improving indoor thermal environment for adjusting thermal comfort. Along with the use of passive means like the use of mechanical devices, the occupants in any dwellings use active means such as the use of natural ventilation, window opening, and clothing adjustment. In fact, the use of active means when the outdoor environment is good enough might be more suitable to improve indoor thermal environment than the use of mechanical air conditioning units, which necessarily require electricity. Therefore, the people in developing countries like Nepal need to understand to what extent the occupants can use active means to manage their own indoor thermal comfort. The use of active means during good outdoor environment might be an effective way to manage increasing energy demand in the future. We have made a field survey on the occupants’ adaptive behaviors for thermal comfort in a Japanese condominium equipped with Home Energy Management System (HEMS). Online questionnaire survey was conducted in a condominium with 356 families from November 2015 to October 2016 to understand the occupants’ behaviors. The number of 17036 votes from 39 families was collected. The indoor air temperature, relative humidity and illuminance were measured at the interval of 2-10 minutes to know indoor thermal environmental conditions. The occupants were found using different active behaviors for thermal comfort adjustments even in rather harsh summer and winter. Around 80% of the occupants surveyed opened windows when the outdoor air temperature was 30⁰C in free running (FR) mode and the clothing insulation was 0.93 clo when the outdoor air temperature was 0⁰C. The result showed that the use of mechanical heating and cooling was not necessarily the first priority to improve indoor thermal environment. Our result along with other results in residential buildings showed that the adaptive behaviors of the occupants are one of the primary ways to adjust indoor thermal comfort. This fact is important in enhancing the energy saving building design.

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