Effect of Indoor Temperature Setpoint on HVAC Energy Use and Thermal Comfort in Tropical Classrooms
Keywords:
HVAC, Setpoint Temperature, Energy Consumption, Thermal Comfort, Tropical ClimateAbstract
Heating, Ventilation, and Air-Conditioning (HVAC) systems contribute significantly to electricity consumption in tropical educational buildings due to continuous cooling demand. This study evaluates the influence of indoor temperature setpoints on cooling energy consumption and thermal comfort in two university classrooms equipped with split air-conditioning systems in Medan, Indonesia, using EnergyPlus simulations. Six temperature setpoints ranging from 20°C to 25°C were analyzed under identical operational and climatic conditions. Thermal comfort performance was assessed using the Predicted Mean Vote (PMV) method based on ASHRAE Standard 55. To verify the representativeness of the climatic input data, the outdoor dry-bulb temperature obtained from the EPW weather file was compared with observed outdoor temperature data collected on 30 May 2026, resulting in a relative error of 2.26%. The results show that increasing the setpoint temperature reduced annual cooling electricity consumption from 5,515 kWh to 3,607 kWh in Room J20.301 and from 5,284 kWh to 3,581 kWh in Room J20.302, corresponding to energy savings of 34.6% and 32.2%, respectively. However, thermal comfort performance decreased as the setpoint increased. At 25°C, PMV values reached 0.71 and 0.73, exceeding the ASHRAE comfort limit and reducing annual comfort compliance to below 1% in both rooms. The 23°C setpoint provided the most balanced performance, with annual energy consumption of 4,379 kWh and 4,292 kWh while maintaining PMV values within the acceptable comfort range at 0.35 and 0.32. Annual comfort compliance at this condition reached 87.6% and 96.1% for Rooms J20.301 and J20.302, respectively.
Downloads
References
[1] Y. Lei, S. Zhan, and A. Chong, “Sustainable cooling in the tropics with mixed-mode ventilation and thermal adaptation,” Building and Environment, vol. 284, p. 113339. 2025.
[2] K. Miyamoto, S. N. Pratiwi, S. Nishiiri, H. Takaguchi, and T. Kubota, “Relationship between Cooling Methods and Energy Consumption for the Development of Low-Carbon Collective Housing in Indonesia,” Sustainability, vol. 16, no. 4, p. 1635. 2024.
[3] P. M. Cuce and E. Cuce, “Role of HVAC in building energy consumption: a critical review,” Journal of Thermal Analysis and Calorimetry, vol. 151, no. 4, pp. 3059–3080. 2026.
[4] S. Li and Y. Chen, “Internal benchmarking of higher education buildings using the floor-area percentages of different space usages,” Energy and Buildings, vol. 231, p. 110574. 2021.
[5] A. Ghahramani, K. Zhang, K. Dutta, Z. Yang, and B. Becerik-Gerber, “Energy savings from temperature setpoints and deadband: Quantifying the influence of building and system properties on savings,” Applied Energy, vol. 165, pp. 930–942. 2016.
[6] L. Chang, I. Permana, T. Setiawan, A. P. Agharid, and F. Wang, “Evaluating and enhancing thermal comfort and indoor air quality in a library building through measurement and simulation,” Ain Shams Engineering Journal, vol. 16, no. 10, p. 103580. 2025.
[7] D. Grassie, K. Milczewska, S. Renneboog, F. Scuderi, and S. Dimitroulopoulou, “Impact of Indoor Air Quality, Including Thermal Conditions, in Educational Buildings on Health, Wellbeing, and Performance: A Scoping Review,” Environments, vol. 12, no. 8, p. 261. 2025.
[8] Y. Pan, M. Zhu, Y. Lv, Y. Yang, Y. Liang, R. Yin, Y. Yang, X. Jia, X. Wang, F. Zeng, S. Huang, D. Hou, L. Xu, R. Yin, and X. Yuan, “Building energy simulation and its application for building performance optimization: A review of methods, tools, and case studies,” Advances in Applied Energy, vol. 10, p. 100135. 2023.
[9] D. B. Crawley, L. K. Lawrie, F. C. Winkelmann, W. F. Buhl, Y. J. Huang, C. O. Pedersen, R. K. Strand, R. J. Liesen, D. E. Fisher, M. J. Witte, and J. Glazer, “EnergyPlus: creating a new-generation building energy simulation program,” Energy and Buildings, vol. 33, no. 4, pp. 319–331. 2001.
[10] Z. Wang and M. Gadi, “Optimal HVAC setpoints for energy efficiency and thermal comfort in Chinese residential buildings,” Journal of Building Engineering, vol. 96, p. 110286. 2024.
[11] D. Sánchez-García, D. Bienvenido-Huertas, J. Martínez-Crespo, and R. de Dear, “Using setpoint temperatures based on adaptive thermal comfort models,” Building and Environment, vol. 258, p. 111647. 2024.
[12] F. Tartarini and S. Schiavon, “Comparative analysis of PMV Models accuracy implemented in the ISO 7730:2005 and ASHRAE 55:2023,” Building and Environment, vol. 275, p. 112766. 2025.
[13] W. H. Mitrakusuma, A. Badarudin, Susilawati, H. Najmudin, and A. Setyawan, “Performance of Split-type Air Conditioner under Varied Outdoor Air Temperature at Constant Relative Humidity,” Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, vol. 90, no. 2, pp. 42–54. 2022.
[14] Y. Huang and J. Niu, “Application of super-insulating translucent silica aerogel glazing system on commercial building envelope of humid subtropical climates – Impact on space cooling load,” Energy, vol. 83, pp. 316–325. 2015.
[15] X. Xu, L. Xia, M. Chan, and S. Deng, “Inherent correlation between the total output cooling capacity and equipment sensible heat ratio of a direct expansion air conditioning system under variable-speed operation (XXG SMD SHR DX AC unit),” Applied Thermal Engineering, vol. 30, no. 13, pp. 1601–1607. 2010.
[16] C. F. Pinnola, J. V. C. Vargas, C. L. Buiar, and J. C. Ordonez, “Energy consumption reduction in existing HVAC-R systems via a power law controlling kit,” Applied Thermal Engineering, vol. 82, pp. 341–350. 2015.
[17] R. Liang, W. Ding, Y. Zandi, A. Rahimi, S. Pourkhorshidi, and M. A. Khadimallah, “Buildings’ internal heat gains prediction using artificial intelligence methods,” Energy and Buildings, vol. 258, p. 111794. 2022.
[18] L. Yang, H. Yan, and J. C. Lam, “Thermal comfort and building energy consumption implications – A review,” Applied Energy, vol. 115, pp. 164–173. 2014.
[19] A. Reilly and O. Kinnane, “The impact of thermal mass on building energy consumption,” Applied Energy, vol. 198, pp. 108–121. 2017.
[20] K. Dharmasastha, D. G. L. Samuel, S. M. S. Nagendra, and M. P. Maiya, “Impact of indoor heat load and natural ventilation on thermal comfort of radiant cooling system: An experimental study,” Energy and Built Environment, vol. 4, no. 5, pp. 543–556. 2023.
[21] K. O. Amoabeng, R. Opoku, S. Boahen, and G. Y. Obeng, “Analysis of indoor set-point temperature of split-type ACs on thermal comfort and energy savings for office buildings in hot-humid climates,” Energy and Built Environment, vol. 4, no. 3, pp. 368–376. 2023.
[22] T. Chaudhuri, Y. C. Soh, H. Li, and L. Xie, “A feedforward neural network based indoor-climate control framework for thermal comfort and energy saving in buildings,” Applied Energy, vol. 248, pp. 44–53. 2019.
[23] M. Niknami, S. Maniee, A. A. Farokhi Rad, S. Mansoori, and M. Yahaghi, “An experimental study on the effect of room setpoint temperature, and evaporator/condenser fouling on performance of a ductless split type air conditioner,” Energy and Buildings, vol. 322, p. 114671. 2024.
Additional Files
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 DINAMIS
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
