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.

Quantitative investigations on setting parameters of air conditioning (air-supply speed and temperature) in ventilated cooling rooms

2019 ◽  
Vol 30 (1) ◽  
pp. 99-113 ◽  
Author(s):  
Haofu Chen ◽  
Zhuangbo Feng ◽  
Shi-Jie Cao
Keyword(s):  
Thermal Comfort ◽  
Air Conditioning ◽  
Thermal Environment ◽  
Inertial Force ◽  
Index Formula ◽  
Design Parameters ◽  
Dimensionless Number ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Air Supply

Rational and scientific design of indoor air conditioning is essential. In the design of Heating, Ventilating and Air Conditioning system, air-supply speed (ventilation rate) and air-supply temperature are the two most important parameters. In the current study, numerical simulations and experimental measurements were adopted to investigate the influences of ventilation mode, air-supply velocity and air-supply temperature on indoor thermal comfort as well as building energy consumption in summer. Different ventilation modes (up supply and down exit, ceiling supply and ceiling exit) were considered in modelling. Based on the simulation and experimental results, dimensionless index [Formula: see text] is proposed, which represents the ratio of buoyancy weighting force to inertial force. This index can be used as a pre-evaluation index of indoor thermal comfort in preliminary design of air conditioning. It is an indicator to judge the working conditions in cooling-ventilated rooms. When [Formula: see text], the settlement and diffusion effects of indoor airflow reach a good level, which means that the parameter setting could provide a comfortable indoor thermal environment. The dimensionless number [Formula: see text] is a theoretically based tool in the pre-evaluation of indoor thermal environment, providing guidance for setting of ventilation design parameters.

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 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.

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.

Evaluation of Indoor Thermal Environment in a Radiant-Cooled-Floor Office Building in Malaysia

2014 ◽  
Vol 564 ◽  
pp. 228-233 ◽  
Author(s):  
Qi Jie Kwong ◽  
Mohamad Afri Arsad ◽  
Nor Mariah Adam
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Cooling System ◽  
Thermal Sensation ◽  
Office Building ◽  
Air Velocity ◽  
Variable Air Volume ◽  
Indoor Thermal Environment ◽  
Radiant Cooling ◽  
Comfort Parameters

This paper presents the findings of a thermal comfort survey conducted in a tropical green office building. The building was installed with a slab-integrated radiant cooling system, which operated concurrently with an integrated variable-air-volume system. Evaluation of indoor thermal environment was made, where both objective and subjective assessments were carried out. The air temperature, air velocity, relative humidity and surface temperatures were measured by using calibrated sensors. Based on the data collected from the field assessment, the thermal comforts indices with expectancy factor were calculated. The results showed that thermal comfort parameters were within the comfort range specified in a local guideline, except for the air velocity profile. Besides, discrepancy between the Predicted Mean Vote (PMV) with expectancy factor and Actual Mean Vote (AMV) was found, which showed that the former still overestimated the thermal sensation of occupants although an expectancy factor of 0.5 was used.

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

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
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.

Numerical Simulation of Indoor Thermal Environment of a Double-Skin Facade Office with Different Shutter Angles

2014 ◽  
Vol 694 ◽  
pp. 256-259
Author(s):  
Xin Zhan ◽  
Hua Yang ◽  
Feng Yun Jin
Keyword(s):  
Heat Transfer ◽  
Thermal Environment ◽  
Ventilation Rate ◽  
Air Distribution ◽  
Indoor Thermal Environment ◽  
Double Skin ◽  
Computational Fluid Dynamics Cfd ◽  
Heat Transfer Simulation ◽  
Shading Devices ◽  
Rng Turbulence Model

Airflow and heat transfer simulation was conducted for a double-skin façade (DSF) system equipped with shading devices in the cavity, using computational fluid dynamics (CFD) with RNG turbulence model and PISO algorithm, for five conditions of slat angles (θ=0°, 30°, 45°, 60°, 90°). The present study indicates that the presence of shading devices influences the temperatures, the ventilation rate and the air distribution in the DSF system. Besides, the different angles will make different influences.

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

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.

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

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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