# Modeling Heat Consumption of an Office Building During COVID-19 Restrictions
## 4 Results

Table 7: Economic and energy summary. The additional daily effective thermal inertia of the excessive energy dumped into envelopes and furniture elements was 5078 kWh, which brought 1.46 kWh per unit of gross floor surface area. As [PERSON] et al. [13] reported, the additional daily effective thermal inertia of the interior elements was much smaller and ranged from 6.4 to 68 Wh/Km\({}^{2}\). The results show that the system saved approximately 49.6 MWh of heat to achieve the quasi-steady-state conditions after the night shutdown. To compare, [PERSON] [7] showed that the considered DH system saved about 330 MWh of energy to reach the quasi-steady-state conditions after a night setback. The energy savings of each of the six components ranged between 1080 and 49,647 kWh per day, while the corresponding cost savings were 24.9 and 979.9 EUR as the lower and upper thresholds, respectively. After adopting the indoor temperature feedback, the average temperature was 21.2 \({}^{\circ}\)C with a maximum error of \(\pm\)1.62 \({}^{\circ}\)C. Hence, the methodology may ensure constant thermal comfort and high energy-saving potential. To compare, after [PERSON] et al. [11] adopted their methodology, they obtained a maximum indoor temperature difference of 0.38 \({}^{\circ}\)C and an average error of 0.29 \({}^{\circ}\)C.  
Here, if the operating parameters were adjusted according to the design indoor temperature of 20 \({}^{\circ}\)C all SH season long (from 21 September to 26 April in 2020-2021), the total saving effect in energy demand was 119.7 MWh with the corresponding energy-saving rate of 19.8%. To compare, in [4], the saving effect was achieved at a lower supply temperature, which was highly recommended for an HVAC control system to enhance the physical environment. Indoor comfort was increased by 68% and the energy efficiency by 50%. [PERSON] et al. [11] concluded that if the operating parameters were adjusted according to the target indoor temperature of 23 \({}^{\circ}\)C from November 15 to December 8, the average energy demand would be 37.9 MWh and the associated energy-saving rate was expected to be 5.8 \(\pm\) 0.1%. [PERSON] et al. [6] reported that the heat demand of all studied substations decreased after implementing a new operational strategy, with energy-saving rates of 5.9%, 6.1%, 6.9%, and 10.0%. Employing TRV-related savings and considering thermal inertia may ensure a more stable indoor temperature and higher energy performance. Table 8 shows that the impact on different components varied greatly, with a total heat demand of 603.9 MWh per year, costs of 168.2 keUR, and a difference in specific heat consumption of 35.2 kWh/m\({}^{2}\), which meant less heat demand and a larger cost-saving effect. Before implementing the new control strategy, the average indoor temperature was 23.5 \({}^{\circ}\)C. The heat demand of SH, DHW, and AHU systems ranged between 30 and 430 MWh annually, while corresponding costs were 93.0, 4.22, and 71.0 keUR, respectively. After implementing all the new control strategies, the average indoor temperature was 20.4 \({}^{\circ}\)C with an annual specific heat consumption of 174 kWh/m\({}^{2}\). To compare, [PERSON] et al. [6] showed the obtained specific energy demand per year as follows: 425 kWh/m\({}^{2}\), 327 kWh/m\({}^{2}\), 290 kWh/m\({}^{2}\), and 281 kWh/m\({}^{2}\), as shown for each of the four substations. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Component** & **Energy Demand** & **O\&M Costs** \\
**[MWh/Annum]** & **[kEUR/Annum]** \\ \hline Space Heating & 429.4 & 93.0 \\ DHW & 31.1 & 4.22 \\ AHU Heating & 143.3 & 71.0 \\ Total Base Load \& Costs & 603.9 & 168.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The system’s performance was determined after all the scenarios had been implemented. That resulted in a specific annual consumption of 174 kWh/m\({}^{2}\).