## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Month**} & \multicolumn{2}{c}{**Electricity (B2 Building)**} & \multicolumn{2}{c}{**Natural Gas (B1 Building)**} \\  & \(\mathbf{E_{E}^{2018}}\) & \(\mathbf{E_{E}^{2022}}\) & \(\mathbf{E_{NG}^{2018}}\) & \(\mathbf{E_{NG}^{2022}}\) \\  & (kWh) & (kWh) & (kWh) & (kWh) \\ \hline January & 36,558 & 129,816 & 255,323 & 230,650 \\ February & 34,923 & 106,828 & 268,098 & 174,666 \\ March & 27,907 & 109,959 & 234,103 & 197,583 \\ April & 27,612 & 68,648 & 140,019 & 112,634 \\ May & 32,755 & 56,284 & 59,755 & 22,807 \\ June & 28,688 & 52,368 & 398 & 0 \\ July & 21,816 & 47,797 & 0 & 0 \\ August & 18,083 & 29,397 & 0 & 0 \\ September & 26,591 & 43,586 & 0 & 0 \\ October & 34,640 & 72,771 & 27,129 & 40,236 \\ November & 39,116 & 78,298 & 190,751 & 60,181 \\ December & 32,893 & 80,157 & 134,473 & 85,746 \\ Total & 372,136 & 862,179 & 1,310,049 & 824,086 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Energy consumption of Buildings B1 and B2. The excess electricity consumption due to hot water pumping from B1 \(\left(E_{E-P}^{2018}\right)\) is determined based on several considerations. Firstly, the installed pumping power at the thermal plant is 4645 W, with a simultaneity factor of 0.7 [44]. Additionally, the installed pumping power for the radiant floor is 2000 W. The operation occurs during weekdays within specified periods: the winter period from 6 a.m. to 12 and 3 p.m. to 6 p.m. and the transitional period from 6 a.m. to 10 a.m. The radiant floor pumping operates 24 h a day during the winter period, while neither pumping system operates during the summer period. The consumption for pumping is calculated on a monthly basis, considering the number of weekdays in each month and the operating hours of each pumping system. The detailed results are presented in Table 6.  
The electricity consumption of the heat pumps (HP) in Building B1 \(\left(E_{E-HP}^{2018}\right)\) is determined through a rigorous methodology that incorporates key factors to ensure the reliability of the estimation. First, the monthly heating energy demand per square meter for the spaces conditioned by HPs is calculated based on the natural gas consumption \(\left(E_{GN}^{2018}\right)\) for the rest of the building. This approach allows for a precise correlation between energy demands in different zones of the building. Second, an efficiency factor \(\eta_{LTCB}\) = 0.952 is applied to account for the performance of the Low-Temperature Condensing Boiler (LTCB) system. This value reflects measured operational efficiency under real-world conditions. Third, the heat transmission losses to the exterior, which could occur via conduction and convection, are considered negligible in this study. Specifically, we are referring to the heat transfer from the indoor (conditioned) air within the building to the outdoor environment through the building's envelope. Given that the zones heated by the heat pumps (HPs) are located within the building's interior, the losses to the exterior are minimal. This assumption is based on the fact that the building's thermal envelope provides adequate insulation, limiting the impact of external temperature fluctuations on the indoor environment. To quantify this, a reduction coefficient of 0.6 is applied, as documented in the relevant literature, which reflects the relatively low heat losses under the operational conditions of the building. This coefficient accounts for the fact that in the context of the building's design and insulation, the heat transmission to the exterior is minimal and does not significantly affect the overall energy balance [42]. These assumptions are grounded in \begin{table}
\begin{tabular}{c c c c} \hline \hline
\begin{tabular}{c} Winter (7 h) \\ Radiating f. (24 h) \\ \end{tabular} & 321 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Power consumption pumping in Building B1.