Research on thermal comfort degree response space and energy saving potential of summer air-conditioning

Author(s):  
Qing-Guo Yan ◽  
Chu Chen ◽  
Bin Yang ◽  
Xu-Fang Wang ◽  
Yong-Biao Yang ◽  
...  
Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2160 ◽  
Author(s):  
Joowook Kim ◽  
Doosam Song ◽  
Suyeon Kim ◽  
Sohyun Park ◽  
Youngjin Choi ◽  
...  

Building energy savings and occupant thermal comfort are the main issues in building technology. As such, the development of energy-efficient heating, ventilation, and air-conditioning (HVAC) systems and the control strategies of HVAC systems are emerging as important topics in the HVAC industry. Variable refrigerant flow (VRF) systems have efficient energy performance, so the use of VRF systems in buildings is increasing. However, most studies on VRF systems focus on improving mechanical efficiency, with few studies on energy-efficient control while satisfying the thermal comfort of occupants. The goal is to estimate the energy-saving potential of adjusting the temperature set-points and dead-band (range) in VRF air-conditioned building. To do so, we analyzed the influence of control strategies of a VRF system on human thermal comfort and energy consumption using a simulation method. The results showed that energy consumption can be reduced by 25.4% for predicted mean vote (PMV)-based control and 27.0% for the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) comfort range control compared with the typical set-point temperature control of a VRF system. The indoor thermal environments of the analyzed control strategies are controlled in the thermal comfort range, which is based on a PMV at ±0.5. Compared with the typical set-point control, PMV and ASHRAE comfort range-based control reduced the operation time of the compressor in the VRF system.


2013 ◽  
Vol 316-317 ◽  
pp. 1101-1105
Author(s):  
Ming Ming Sun ◽  
Jian Fa Zhong ◽  
Wei Jun Wu ◽  
Jian Liu ◽  
Zhi Yi Wang

Induces the operating principle of the induced radiation unit and studies the uniformity of indoor temperature distribution in the space and time, comfort and dewing condensation based on the PMV-PPD thermal comfort evaluation system. Through data collation and results analysis, obtains thermal comfort superiority and energy-saving potential of the reduced radiation air conditioning. The results show that the temperature distribution in the room stalled by the reduced radiation units is uniform, without sense of temperature difference and ventilation, providing an ultra-comfortable environment and that the indoor setting temperature can be up to 27°C on the premise of meeting comfort requirement. At the same time, air supply of low temperature can be achieved without condensation, reflecting the energy-saving potential of the system. These provide a reference for design of the induced radiation air conditioning system and further study.


Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 81
Author(s):  
Rongjiang Ma ◽  
Shen Yang ◽  
Xianlin Wang ◽  
Xi-Cheng Wang ◽  
Ming Shan ◽  
...  

Air-conditioning systems contribute the most to energy consumption among building equipment. Hence, energy saving for air-conditioning systems would be the essence of reducing building energy consumption. The conventional energy-saving diagnosis method through observation, test, and identification (OTI) has several drawbacks such as time consumption and narrow focus. To overcome these problems, this study proposed a systematic method for energy-saving diagnosis in air-conditioning systems based on data mining. The method mainly includes seven steps: (1) data collection, (2) data preprocessing, (3) recognition of variable-speed equipment, (4) recognition of system operation mode, (5) regression analysis of energy consumption data, (6) constraints analysis of system running, and (7) energy-saving potential analysis. A case study with a complicated air-conditioning system coupled with an ice storage system demonstrated the effectiveness of the proposed method. Compared with the traditional OTI method, the data-mining-based method can provide a more comprehensive analysis of energy-saving potential with less time cost, although it strongly relies on data quality in all steps and lacks flexibility for diagnosing specific equipment for energy-saving potential analysis. The results can deepen the understanding of the operating data characteristics of air-conditioning systems.


Author(s):  
Lingjiang Huang ◽  
Jian Kang

AbstractThe solar incidence on an indoor environment and its occupants has significant impacts on indoor thermal comfort. It can bring favorable passive solar heating and can result in undesired overheating (even in winter). This problem becomes more critical for high altitudes with high intensity of solar irradiance, while received limited attention. In this study, we explored the specific overheating and rising thermal discomfort in winter in Lhasa as a typical location of a cold climate at high altitudes. First, we evaluated the thermal comfort incorporating solar radiation effect in winter by field measurements. Subsequently, we investigated local occupant adaptive responses (considering the impact of direct solar irradiance). This was followed by a simulation study of assessment of annual based thermal comfort and the effect on energy-saving potential by current solar adjustment. Finally, we discussed winter shading design for high altitudes for both solar shading and passive solar use at high altitudes, and evaluated thermal mass shading with solar louvers in terms of indoor environment control. The results reveal that considerable indoor overheating occurs during the whole winter season instead of summer in Lhasa, with over two-thirds of daytime beyond the comfort range. Further, various adaptive behaviors are adopted by occupants in response to overheating due to the solar radiation. Moreover, it is found that the energy-saving potential might be overestimated by 1.9 times with current window to wall ratio requirements in local design standards and building codes due to the thermal adaption by drawing curtains. The developed thermal mass shading is efficient in achieving an improved indoor thermal environment by reducing overheating time to an average of 62.2% during the winter and a corresponding increase of comfort time.


2012 ◽  
Vol 516-517 ◽  
pp. 1224-1228
Author(s):  
Na Liang ◽  
Rui Li

Due to energy reserves reduces gradually and uneven distribution, all countries pay more and more attention to energy saving and improve the effective utilization of energy, China also attaches great important to this. Energy saving of buildings is a necessary development trend. Air conditioning system as a large important part of building energy consumption has a huge energy-saving potential. This article mainly introduced the related strategies of energy saving in central air conditioning water system from the following three points of view: the water treatment, the cooling tower, and the variable frequency pump.


2014 ◽  
Vol 568-570 ◽  
pp. 1770-1773
Author(s):  
Guang Wei Zhao

Evaporative cooling is able to generate the cooling medium at a temperature approaching to the ambient wet bulb temperature. In this paper, a low-energy air-conditioning strategy is proposed, which is a combination of cooled ceiling (CC),microencapsulated phase change material (MPCM) slurry storage and evaporative cooling technologies. The assessment of evaporative cooling availability and utilization is done for five representative climatic cities, including Hong Kong, Shanghai, Beijing, Lanzhou and Urumqi in China, and the energy saving potential of the proposed air-conditioning system is analyzed by using a well validated building simulation code. The results indicate that the new system offers energy saving potential up to 80% under northwestern Chinese climate and up to 10% under southeastern Chinese climate. The optimal design method of the slurry storage tank is also proposed based on the slurry cooling storage behaviors and cooling demand variations of the ceiling panels.


2020 ◽  
Vol 10 (4) ◽  
pp. 1513 ◽  
Author(s):  
Daniel Sánchez-García ◽  
David Bienvenido-Huertas ◽  
Jesús A. Pulido-Arcas ◽  
Carlos Rubio-Bellido

Reports of Intergovernmental Panel on Climate Change have set various greenhouse gas emissions scenarios, through which the evolution of the temperature of the planet can be estimated throughout the 21st century. The reduction of the emissions from the different activities carried out by mankind is crucial to mitigate greenhouse gas emissions. One of the most significant activities is users’ behaviour within buildings, particularly the use of Heating, Ventilation and Air-Conditioning systems. Modifying users’ behaviour patterns to guarantee acceptable thermal conditions inside buildings could lead to considerable energy saving percentages, and adaptive thermal comfort models could be an opportunity to achieve important savings. For this reason, this study analyzes the potential to apply adaptive thermal comfort models to use artificial air-conditioning systems by modifying setpoint temperatures. The analysis was conducted in five major European cities (Barcelona, Berlin, Bern, Rome, and Vienna) and in five climate change scenarios in the year 2050. The results showed that, in general, the energy saving achieved by adaptive strategies was larger in the cities with a greater cooling demand. Also, in both Representative Concentration Pathways (RCP) of the Fifth Assessment Report (AR5) considered, the energy saving were decreased in the cities of Barcelona and Rome, with values lower than those of the Fourth Assessment Report (AR4) scenarios considered, whereas in the cities of Berlin, Bern, and Vienna, the saving in the RCP scenarios is greater than those in the other scenarios.


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