Yudi Prana Hikmat
| Toto Tohir | Sofyan Muhammad Ilman | Kasni Sumeru | M. Taofik Hidayat | Mohamad Firdaus bin Sukri | Muhammad Nuriyadi*
© 2026 The authors. This article is published by IIETA and is licensed under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).
OPEN ACCESS
Electricity consumption by an air conditioner (A/C) is significantly affected by its performance. The parameters commonly used to indicate A/C performance are power input, cooling capacity, and coefficient of performance (COP). Air conditioning is considered to have better performance when the power input is lower, the cooling capacity is greater, and the COP is higher. A/C performance is affected by outdoor air temperature; the lower the outdoor air temperature, the higher the performance. In this study, the effect of outdoor air temperature on split A/C performance will be investigated quantitatively. This research was conducted on a split A/C with a power input of 840 W and using R32 as the working fluid. The study examines the effect of outdoor air temperature (19 ℃–32 ℃) on split A/C performance. Results show that each 1 ℃ increase leads to a 2.04% drop in COP and a 0.02 kWh rise in electricity consumption.
outdoor air, electricity consumption, power input, cooling capacity, coefficient of performance
Electrical energy consumption by buildings, both residential and commercial, globally accounts for 30% and contributes to global CO2 emissions by 15% [1]. Meanwhile, air conditioning is the largest electricity consumer in buildings [2, 3]. Therefore, several technologies were developed to reduce electricity consumption, including inverters to regulate compressor rotation [4-6] and nanoparticles mixed in compressor lubricant [7-9]. In addition to the use of these technologies, the outdoor air temperature also greatly affects the A/C's electricity consumption.
Outdoor air conditions are generally expressed by dry tube temperature and relative humidity (RH). For the case in Indonesia, when the outdoor air temperature increases, the RH will decrease. For example, in the morning and evening, the outdoor temperature is lower than at noon, but the RH in the morning and evening is much higher than at noon [10, 11]. The nameplate generally states the A/C performance, e.g., cooling capacity 9000 Btu/h, power input 840 W. However, when installed, the cooling capacity and power input may differ from the nameplate, either higher or lower. For example, an A/C with a cooling capacity of 9000 Btu/h, when installed in the Jakarta area, which has a hot outdoor air temperature, can produce 9000 Btu/h according to specifications, but when installed in Bandung, which has a lower air temperature will produce a cooling capacity of more than 9000 Btu/h.
Outdoor air temperature greatly affects the performance of air conditioners, namely power consumption, cooling capacity, and coefficient of performance (COP) [12-14]. When the temperature is low, the AC power input decreases and the cooling capacity increases. In other words, for the same A/C capacity and the same number of operating hours, the A/C electricity cost in Jakarta will be higher than that in Bandung, because the outdoor air temperature in Jakarta is higher than in Bandung, both in the morning, afternoon, and evening. One of the main reasons for the increase in electricity consumption due to high outdoor air temperature is that it increases the condensing temperature, resulting in increased compressor work [15, 16]. In other words, one method of improving split A/C performance to reduce electricity consumption is to place the outdoor unit in a shaded location that is not exposed to direct sunlight.
Some studies that discuss changes in AC performance due to changes in outdoor air temperature are among others Yau and Pean [14]; Joudi and Al-Amir [17]; Setyawan and Badarudin [18]; and Mitrakusuma et al. [19]. Yau and Pean [14] conducted tests on split A/C and reported that every 1 ℃ increase in outdoor air temperature resulted in a 2% decrease in cooling capacity and COP. Another study with split A/C was conducted by Joudi and Al-Amir [17] by varying the outdoor air temperature from 35 ℃ to 55 ℃. Based on their test using R290 instead of R22 in a split A/C, they reported that power consumption increased from 2.2 kW to 2.75 kW, and COP dropped by 20.7%. Further research was conducted by Setyawan and Badarudin [18] on a split A/C with a capacity of 2 HP and a cooling capacity of 5272 W. The research was conducted indoors where the outdoor air condition could be controlled. Tests were conducted by varying the RH of the outdoor air, but the outdoor air temperature was maintained constant. The results reported that changes in relative RH did not change the cooling capacity; the change that occurred was only 1.2% for changes in RH from 40% to 70%. Other research was conducted by Mitrakusuma et al. [19], who conducted their research on a split A/C using R32 as the working fluid and a cooling capacity of 2.6 kW. The study was conducted in a room where the outdoor air conditions can be controlled, namely by varying the outdoor air temperature while keeping the RH constant. The results reported that an increase in outdoor air temperature by 1 ℃ resulted in an increase in evaporating temperature, suction temperature, discharge temperature, and condensing temperature by 0.27 ℃, 0.08 ℃, 1.08 ℃, and 1.04 ℃, respectively. A 1 ℃ increase in outdoor air temperature also decreased the power input by 1.6%. Their research also reported that a 1 ℃ increase in outdoor air temperature decreased cooling capacity and EER by 1% and 2.1, respectively.
The purpose of this study is to quantitatively observe the change in performance of an installed split A/C due to changes in outdoor air temperature. The performance changes of A/C splits in previous studies [18, 19] were carried out in a room conditioned for testing (thermodynamic room), while in this study, observations were made on the installed A/C split. The outdoor air temperature at the unit location varies with natural conditions. In other words, this study only reports changes in split A/C performance due to temperature changes. While changes in RH in this study were not considered, research conducted by Setyawan and Badarudin [18] reported that changes in RH have no significant effect on split A/C performance when the outdoor air temperature is constant. Significant changes in AC performance are driven solely by outdoor air temperature variations [19]. Thermodynamically, when operating at high ambient temperatures, the refrigerant must be condensed at correspondingly higher pressures and temperatures, which necessitates greater compressor work and leads to higher energy absorption.
2.1 Test facilities
Based on the specifications contained in the A/C nameplate, the research was conducted on a split A/C that has a cooling capacity of 9000 Btu/h with a power input of 840 W and uses R32 as the working fluid. The study was conducted on split A/Cs because this type is the most widely used in many countries [20, 21]. While R32 refrigerant is a type of refrigerant that began to be widely used in split air conditioners in Indonesia since 2015, in that year it was banned the use of R22 in new split A/C [22], because R22 still has a very high global warming potential (GWP) [23].
The tested air conditioner is shown in Figure 1. The indoor unit is installed in the room used for meetings, while the outdoor unit is placed outside the room on the west-facing side, so that in the afternoon, the outdoor unit is exposed to direct sunlight.
To get accurate data, this research utilized several pieces of equipment, namely a thermocouple, pressure gauge, clamp-on ammeter, and Voltmeter. The accuracy of each piece of equipment is shown in Table 1. From the table, it can be seen that the pressure gauge used to measure low pressure and high pressure has different accuracy and range.
Figure 1. Outdoor and indoor split A/C unit as the object of testing
Table 1. The accuracies of measuring equipment
|
Equipment |
Accuracy |
Range |
|
Thermocouple |
±0.1 ℃ |
-50 to 1300 ℃ |
|
High pressure gauge |
±0.5 bar |
0 to 55 bar |
|
Low pressure gauge |
±0.1 bar |
-1 to 35 bar |
|
Clamp-on-ammeter |
±0.1 A |
0 to 600 V |
|
Voltmeter |
±1 V |
0 to 400 A |
2.2 Test method
To obtain variations in outdoor air temperature, tests were conducted in the early morning, morning, noon, afternoon, and evening. The outdoor air temperature changes observed were 19 ℃, 22 ℃, 26 ℃, 28 ℃, and 32 ℃. Based on the test, it was found that the split A/C performance changes due to changes in outdoor air temperature from the coldest to the hottest at the location where the air conditioner is installed. The A/C parameters that are observed to change due to changes in outdoor air temperature are suction and discharge temperatures and pressures, condenser outlet temperature, evaporator outlet temperature, and electric current.
Figure 2. Refrigeration cycle of split-type A/C on the P-h diagram [24]
The measurement results for each outdoor air temperature will be depicted on a P-h diagram as shown in Figure 2. The figure shows two refrigeration cycles, which are colored blue and red. The blue line represents a lower ambient temperature, while the red line indicates a higher ambient temperature. It can be seen from the figure that the enthalpy difference (2’-1’, red line) is higher than that of (2-1, blue line).
A higher enthalpy difference indicates higher power consumption by the compressor. It can be seen in the figure that the increase in outdoor temperature results in an increase in compressor discharge pressure, from point 2 to point 2'. As a result of this increase in discharge pressure, the condensing temperature will increase. Because in this study five different outdoor air temperatures were tested, there will also be five refrigeration cycles with different values of evaporating and condensing temperatures on the P-h diagram.
Based on the P-h diagram in Figure 2, the equations to calculate compression work, power input, refrigeration effect, cooling capacity, COP, and electricity consumption are shown by the following equations:
$W=\left(h_1-h_2\right)$ (1)
$P=V \cdot I$ (2)
$\dot{m}=\frac{V \cdot I \cdot \cos \varphi}{\left(h_2-h_1\right)}$ (3)
$R E=\left(h_1-h_3\right)$ (4)
$Q=\dot{m}\left(h_1-h_3\right)$ (5)
$\operatorname{COP}=\frac{Q}{P}=\frac{\left(h_1-h_3\right)}{\left(h_2-h_1\right)}$ (6)
$E C=V \cdot I \cdot h$ (7)
Meanwhile, to calculate the increase in electricity consumption and decrease in COP due to an increase in outdoor air temperature (from t1 to t2), Eqs. (8) and (9) are used,
$P_{i n c}=\frac{\left(P_{t 2}-P_{t 1}\right)}{P_{t 2}}$ (8)
$C O P_{\text {dec }}=\frac{\left(C O P_{t 1}-C O P_{t 2}\right)}{C O P_{t 1}}$ (9)
where,
$W$ = compression work
$P$ = power input
$R E$ = refrigeration effect
Q = cooling capacity
$\dot{m}$ = mass flow rate of refrigerant
$\cos \varphi$ = power factor
$E C$ = electricity consumption
$h_1$ = specific enthalpy at point 1
$h_2$ = specific enthalpy at point 2
$h_3$ = specific enthalpy at point 3
$P_{\text {inc}}$ = power input increment
$C O P_{\text {dec}}$ = COP decrement
$P_{t 1}$ = power consumption at t1 (lower temperature)
$P_{t 2}$ = power consumption at t2 (higher temperature)
Thermodynamically, the change in electricity consumption by air conditioners is not only measured by the change in power input to the compressor, but also by the change in cooling capacity generated by the evaporator. As an illustration, in the case of replacing refrigerant from R134a with R290 in a refrigeration machine [25], a 33.3% decrease in compressor power input was reported. However, because it was followed by a 51.0% decrease in cooling capacity, the COP decreased by 26.3%. As the COP decreases, electricity consumption increases by the COP decrease, i.e., 26.3%. The increase in electricity consumption of the refrigerator or A/C is as much as the decrease in COP, not as much as the decrease in compressor power consumption, which is 33.3%. This explanation will be used as the basis for the results and discussion chapter.
This study presents quantitative data on the changes in split A/C performance due to changes in outdoor air temperature. The main performance changes of the split A/C, namely power input, cooling capacity, and COP, were discussed. The data showed that the higher outdoor air temperature led to an increase in power input and a decrease in cooling capacity and COP. The average increase in power input and decrease in cooling capacity for each 1 ℃ increase in outdoor air temperature were 1.48% and 0.70%, respectively. The increase in power input and decrease in capacity resulted in a decrease in COP. With the decrease in COP, the split AC electricity consumption also increased. The average COP decrease per 1 ℃ increase in outdoor temperature was 2.04%. The increase in electricity consumption from 19 ℃ to 32 ℃ outdoor temperature was 0.28 kWh, or an average of 0.02 kWh for each 1 ℃ increase in outdoor air temperature.
The authors would like to thank the Department of Electrical Engineering and Refrigeration and Air Conditioning Engineering of Politeknik Negeri Bandung for allowing the use of their facilities for this research.
|
$W$ |
compression work, W |
|
$P$ |
power input, W |
|
$R E$ |
refrigeration effect, kJ·kg-1 |
|
Q |
cooling capacity, W |
|
$\dot{\mathrm{m}}$ |
mass flow rate of refrigerant, kg·s-1 |
|
$\cos \varphi$ |
power factor |
|
$E C$ |
electricity consumption, W.h |
|
$h_1$ |
specific enthalpy at point 1, kJ·kg-1 |
|
$h_2$ |
specific enthalpy at point 2, kJ·kg-1 |
|
$h_3$ |
specific enthalpy at point 3, kJ·kg-1 |
|
$P_{\text {inc}}$ |
power input increment |
|
$C O P_{\text {dec}}$ |
COP decrement |
|
$P_{t 1}$ |
power consumption at t1 (lower temperature) |
|
$P_{t 2}$ |
power consumption at t2 (higher temperature) |
[1] Balbis-Morejón, M., Cabello-Eras, J.J., Rey-Martínez, F.J., Fandiño, J.M.M., Rey-Hernández, J.M. (2024). Energy performance of a university building for different air conditioning (AC) technologies: A case study. Buildings, 14(6): 1746. https://doi.org/10.3390/buildings14061746
[2] Li, X., Chen, S., Li, H., Lou, Y., Li, J. (2023). A behavior-orientated prediction method for short-term energy consumption of air-conditioning systems in buildings blocks. Energy, 263: 125940. https://doi.org/10.1016/j.energy.2022.125940
[3] McRae, S. (2023). Residential electricity consumption and adaptation to climate change by Colombian households. Economics of Disasters and Climate Change, 7(2): 253-279. https://doi.org/10.1007/s41885-023-00131-3
[4] Wang, C., Wang, B., Cui, M., Wei, F. (2022). Cooling seasonal performance of inverter air conditioner using model prediction control for demand response. Energy and Buildings, 256: 111708. https://doi.org/10.1016/j.enbuild.2021.111708
[5] Lei, L., Li, Z. (2024). A novel dynamic predictive control model for variable air volume air conditioning systems using deep learning. Journal of Building Engineering, 95: 110314. https://doi.org/10.1016/j.jobe.2024.110314
[6] Giannetti, N., Yamaguchi, S., Saito, K., Miyaoka, Y., Tanaka, K., Ogami, H. (2020). Experimental implementation of artificial neural network for cost effective and non-intrusive performance estimation of air conditioning systems. Applied Thermal Engineering, 181: 115985. https://doi.org/10.1016/j.applthermaleng.2020.115985
[7] Adelekan, D.S., Ohunakin, O.S., Babarinde, T.O., et al. (2017). Experimental performance of LPG refrigerant charges with varied concentration of TiO2 nano-lubricants in a domestic refrigerator. Case Studies in Thermal Engineering, 9: 55-61. https://doi.org/10.1016/j.csite.2016.12.002
[8] Jia, T., Wang, R., Xu, R. (2014). Performance of MoFe2O4–NiFe2O4/Fullerene-added nano-oil applied in the domestic refrigerator compressors. International Journal of Refrigeration, 45: 120-127. https://doi.org/10.1016/j.ijrefrig.2014.06.001
[9] Said, Z., Rahman, S.M.A., Sohail, M.A., BS, B. (2023). Analysis of thermophysical properties and performance of nanorefrigerants and nanolubricant-refrigerant mixtures in refrigeration systems. Case Studies in Thermal Engineering, 49: 103274. https://doi.org/10.1016/j.csite.2023.103274
[10] Liu, Y., Bi, L., Hu, R., Ye, L., Zheng, W., Lan, Y. (2025). Microclimate of outdoor tree-lined boulevards in university campuses in hot summer and cold winter regions: A case study of a university in Guilin. Buildings, 15(9): 1476. https://doi.org/10.3390/buildings15091476
[11] Jaafar, H., Lakkis, I., Yeretzian, A. (2022). Impact of boundary conditions in a microclimate model on mitigation strategies affecting temperature, relative humidity, and wind speed in a Mediterranean city. Building and Environment, 210: 108712. https://doi.org/10.1016/j.buildenv.2021.108712
[12] Setyawan, A., Najmudin, H., Badarudin, A., Sunardi, C. (2022). Evaluation of split-type air conditioner performance under constant outdoor moisture content and varied dry-bulb temperature. International Journal of Heat and Technology, 40(5): 1277-1286. https://doi.org/10.18280/ijht.400521
[13] Kibria, M.T., Islam, M.A., Saha, B.B., Nakagawa, T., Mizuno, S. (2019). Assessment of environmental impact for air-conditioning systems in Japan using HFC based refrigerants. Evergreen, 6(3): 246-253. https://doi.org/10.5109/2349301
[14] Yau, Y.H., Pean, H.L. (2014). The performance study of a split type air conditioning system in the tropics, as affected by weather. Energy and Buildings, 72: 1-7. https://doi.org/10.1016/j.enbuild.2013.12.010
[15] Setyawan, A. (2020). Effect of air flow obstruction in a condensing unit on split air conditioner performance. Jurnal Teknologi, 82(5): 23-30. https://doi.org/10.11113/jt.v82.14185
[16] Elsayed, A.O., Hariri, A.S. (2011). Effect of condenser air flow on the performance of split air conditioner. In World Renewable Energy Congress, Sweden2011, pp. 8-13. https://doi.org/10.3384/ecp110572134
[17] Joudi, K.A., Al-Amir, Q.R. (2014). Experimental assessment of residential split type air-conditioning systems using alternative refrigerants to R-22 at high ambient temperatures. Energy Conversion and Management, 86: 496-506. https://doi.org/10.1016/j.enconman.2014.05.036
[18] Setyawan, A., Badarudin, A. (2020). Performance of a residential air conditioning unit under constant outdoor air temperature and varied relative humidity. IOP Conference Series: Materials Science and Engineering, 830(4): 042032. https://doi.org/10.1088/1757-899X/830/4/042032
[19] Mitrakusuma, W.H., Badarudin, A., Najmudin, H., Setyawan, A. (2022). 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, 90(2): 42-54. https://doi.org/10.37934/arfmts.90.2.4254
[20] Nada, S.A., Said, M.A. (2017). Performance and energy consumptions of split type air conditioning units for different arrangements of outdoor units in confined building shafts. Applied Thermal Engineering, 123: 874-890. https://doi.org/10.1016/j.applthermaleng.2017.05.104
[21] Atmaca, İ., Şenol, A., Çağlar, A. (2022). Performance testing and optimization of a split-type air conditioner with evaporatively-cooled condenser. Engineering Science and Technology, an International Journal, 32: 101064. https://doi.org/10.1016/j.jestch.2021.09.010
[22] Setiawan, W., Yuono, L.D., Ridhuan, K., Rajabiah, N. (2022). Kajian eksperimental pemakaian Hidrokarbon Musicool 22 sebagai pengganti R 22 untuk mesin pengatur udara AC split terhadap konsumsi listrik. ARMATUR: Artikel Teknik Mesin & Manufaktur, 3(1): 46-52. https://doi.org/10.24127/armatur.v3i1.1938
[23] Oruc, V., Devecioğlu, A.G. (2015). Thermodynamic performance of air conditioners working with R417A and R424A as alternatives to R22. International Journal of Refrigeration, 55: 120-128. https://doi.org/10.1016/j.ijrefrig.2015.03.021
[24] Wellid, I., Sumeru, K., Badarudin, A. (2025). Performance evaluation of automotive air-conditioner using condensate drain as discharge line cooler. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 129(2): 256-265. https://doi.org/10.37934/arfmts.129.2.256265
[25] Pramudantoro, T.P., Muliawan, R., Nuriyadi, M., Hidayat, S., Tohir, T., Sulaimon, S. (2024). Energy and exergy analysis of chest freezer using R134a and R290 as working fluids based on experimental data. International Journal Applied Technology Research, 5(2): 85-96. https://ijatr.polban.ac.id/ijatr/article/view/153/76.
