Assessment of Energy-Saving Potential of Air Conditioning Systems Using Low-Enthalpy Outdoor Air in Hot-Humid Climate of Thailand
Assessment of Energy-Saving Potential of Air Conditioning Systems Using Low-Enthalpy Outdoor Air in Hot-Humid Climate of Thailand
Keywords:
Air conditioning system, Low-Enthalpy, Energy savingAbstract
Air conditioning systems are among the highest energy-consuming components in buildings, particularly in hot-humid climates such as Thailand, where cooling demand continues to rise. The economizer system-introducing outdoor air with lower enthalpy to reduce cooling loads - has gained attention as a potential energy-saving measure. However, its application in humid climates remains challenging due to high relative humidity. Therefore, the objective of this study is to assess the feasibility and energy-saving potential of economizer applications in Thailand by analyzing suitable climatic conditions and time periods, and to provide insights for practical design and implementation. This study utilized daily weather data during the winter season between 2024 and 2025, obtained from representative stations in five regions of Thailand: Chiang Rai (North), Nakhon Phanom (Northeast), Lopburi (Central), Nakhon Nayok (East), and Prachuap Khiri Khan (South). Three time periods were analyzed: full day (24 hours), working hours (08:00 - 17:00), and nighttime (20:00 - 06:00). The hourly enthalpy calculations indicated that suitable conditions for economizer operation occur when the enthalpy is below 50.465 kJ/kg and the outdoor air temperature ranges between 20 and 28.7 °C. Based on this criterion, the number of hours in which outdoor air could be utilized varied across regions; for example, Nakhon Phanom recorded 432 h/year (all-day period), Nakhon Nayok 279 h (Office time), and Lopburi 157 h (Night time). Furthermore, the energy-saving potential analysis indicated that Lopburi and Prachuap Khiri Khan achieved the highest absolute reductions, whereas Nakhon Nayok exhibited the highest percentage savings (12.56%) despite the smaller actual reduction. In contrast, the southern region showed the lowest savings proportion (0.27 - 2.5%), even though energy consumption was relatively high during certain periods. In summary, the implementation of economizers in Thailand exhibits varying potential depending on region and time period. Appropriate selection based on local temperature and humidity conditions can enhance system performance and support the development of sustainable energy-efficient buildings.
References
K. Lundgren-Kownacki, E. D. Hornyanszky, T. A. Chu, J. Alkan Olsson, and P. Becker, “Challenges of using air conditioning in an increasingly hot climate,” International Journal of Biometeorology, vol. 62, Special Issue on Trans-disciplinary approaches to climate change, pp.401-412, Mar.2018.
Z. Tao, X. Zhu, G. Xu, D. Zou, and G. Li, “A comparative analysis of outdoor thermal comfort indicators applied in China and other countries,” Sustainability, vol. 15, no. 22, Art.no.16029, 2023. doi: 10.3390/su152216029.
J. Feng, M. Liu, and X. Pang, Economizer control using mixed air enthalpy. Energy Systems Laboratory, University of Nebraska–Lincoln, 2007.
B. Li, P. Wild, and A. Rowe, “Free cooling potential of air economizer in residential houses in Canada,” Building and Environment, vol. 167, Art.no.106460, 2019. doi: 10. 1016/j. buildenv.2019.106460.
H. Selamat, M. Mohammad, M. Badiei, and H. Razali, “Review on HVAC system optimization towards energy saving building operation,” International Energy Journal, vol. 20, no.3, pp. 345-358, 2020.
S. T. Taylor and C. H. Cheng, “Why enthalpy economizers don’t work,” ASHRAE Journal, vol. 52, no. 11, pp. 12–20, Nov. 2010.
ASHRAE, “ASHRAE journal QA: Why enthalpy economizers don’t work,” ASHRAE Journal, Nov. 2010.
R. Jirakanvasan, Air conditioning. Bangkok: Thai Air Conditioning Engineering Association, 2018. (in Thai).
Ministry of Industry, TIS 2714 Part 1-2558: Standard for air-cooled air conditioners and heat pumps - Testing and seasonal performance factor calculation, Part 1: Cooling seasonal performance factor, 2016. (in Thai).
T. Manee-wattana, “Ventilation rate calculation according to ASHRAE 62.1 standard,” Technical article of Thai Air Conditioning Engineering Association, Department of Mechanical Engineering, Faculty of Engineering, Chulalongkorn University. (in Thai).
Y. Yao and L. Wang, “Energy analysis on VAV system with different air-side economizers in China,” Energy and Buildings, vol. 42, no. 8, pp. 1220–1230, 2010. doi: 10.1016/jenbuild. 2010. 02.015.
J. E. Seem and J. M. House, “Development and evaluation of optimization-based air economizer strategies,” Applied Energy, vol. 87, no. 3, pp. 910–924, 2010. doi: 10.1016/j. apenergy.2009.08.044.
N. Asim, M. Badiei, M. Mohammad, H. Razali, A. Rajabi, and L. C. Haw, “Sustainability of heating, ventilation and air-conditioning (HVAC) systems in buildings – An overview,” International Journal of Environmental Research and Public Health, vol. 19, no. 2, Art.no. 1016, 2022. doi: 10.3390/ ijerph19021016.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2025 The Journal of Industrial Technology Thepsatri Rajabhat University
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
This article is published under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0), which allows others to share the article with proper attribution to the authors and prohibits commercial use or modification. For any other reuse or republication, permission from the journal and the authors is required.
