## 6 Results and Discussions  
Table 2 shows the pump parameters in the points of the pump duty cycle according to the characteristics of the manufacturer's catalog [26]. Table 3 and Figure 3 show the motor efficiency in the leading points specified in the catalog (50%, 75%, and 100% of the rated motor output power) [23; 24; 25]. In addition, Table 3 specifies the interpolated motor efficiency in the points of the pump duty cycle (75%, 100%, and 110% of the rated flow). All motors under consideration have identical frame size 280S/M and identical mounting dimensions. \begin{table}
\begin{tabular}{c c c c} \hline
**No. of Loading Points (\(i\))** & **1** & **2** & **3** \\ \hline \(Q_{i}\), \% & 75 & 100 & 110 \\ \(Q_{i}\), m\({}^{3}\)/h & 264.0 & 352.0 & 387.2 \\ \(H_{pump.i}\), m & 55.8 & 50.3 & 47.2 \\ \(\eta_{pump.i}\), \% & 76.22 & 81.00 & 79.85 \\ \(P_{mech.i}\), W & 52,538 & 59,520 & 62,421 \\ \(P_{mech.i}\), \% & 70.05 & 79.36 & 83.23 \\ \hline \end{tabular}
\end{table} 
Table 2: Pump loading cycle parameters. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{\(m\)} & \multirow{2}{*}{\
\begin{tabular}{c} **Type of** \\ **Motor, IE** \\ **Class** \\ \end{tabular} } & \multicolumn{2}{c}{**Catalog Efficiency, \% at the Loads**} & \multicolumn{2}{c}{
\begin{tabular}{c} **Interpolated Efficiency \(\eta_{M.i.m}\), \% in** \\ **the Loading Points** \\ \end{tabular} } \\  & **M Class** & **50\%** & **75\%** & **100\%** & **1** & **2** & **3** \\ \hline
1 & IM, IE4 & 95.5 & 96.1 & 96.2 & 96.05 & 96.15 & 96.18 \\
2 & IM, IE3 & 94.5 & 95.1 & 95.2 & 95.07 & 95.17 & 95.19 \\
3 & IM, IE2 & 93.8 & 94.4 & 94.4 & 94.37 & 94.40 & 94.40 \\ \hline \end{tabular}
\end{table} 
Table 3: Catalog and interpolated efficiencies of 75 kW 4-pole electric motors. In Table 5 sign \"*\" indicates the application of the PEF factor to the values without \"*\". In the case of replacing the IE2-motor with the IE4 motor as a part of the pump unit during a planned renovation, the 20 years energy saving is 192.6 MW-h, which saves 29,590\(\epsilon\) for the 20 years; the payback period is 2.9 years. In the case of the IE3 motor, the 20 years energy saving is 82.4 MW-h, which saves the 20 years cost for 12,590\(\epsilon\), and the payback period is 5.2 years. Therefore, it can be concluded that replacing the IE2-motor with either the IE3-motor or IE4 motor is a feasible solution. Even though the initial investment cost of the IE4-motor is higher compared to the IE3-  
pump unit is carried out. The calculations are based on the manufacturers of the pump and electric motors datasheets. The hydraulic flow variation in the range of 75-110% of the rated pump value is considered. The payback period is assessed in the case of replacing the motor as a part of the pump unit during a planned renovation. The initial investment cost of the IE4-motor is higher comparing to the IE3-motor. However, the payback period of the IE4-motor is only 2.9 years and much shorter than that of the IE3 motor. Therefore, even with the higher initial investment cost, the IE4-motor is significantly more profitable. It should be highlighted that the proposed technical solution is especially relevant considering the requirements of the European Commission Regulation [5], according to which, the use of IE4-class motors for a range of the rated power above 75 kW is mandatory from 1 July 2023. The replacement of the IE2-motor also results in a significant reduction in CO\({}_{2}\) emissions. It is 8.87 tons per annum in the case of the IE4-motor and 3.78 tons per annum in the case of the IE3-motor. In addition, the paper presents the calculation methods for energy consumption, energy savings, cost savings, and carbon dioxide emission intensity which can be useful for companies, researchers, and engineers for quick assessment and selection of technical solutions. Conceptual approach, V.P. and V.G. ; data curation V.D., and V.K. ; software V.G. and V.K. ; calculations and modeling, V.G, V.P., and V.K. ; writing of original draft, V.G., V.P., V.K., and V.D.