## 4 Discussion
In addition, the floor area for each residential building type per climate zone was considered through the statistics for the existing floor area per building type [43; 65] and following the methodology proposed by the Spanish Directorate for Architecture, Housing and Planning [36]. In a scenario where all Spanish residential buildings are conditioned, moving the conditioning system's thermostat 1 \({}^{\circ}\)C could lead to a savings of up to 26.0 GWh/year in thermal energy for heating and 8.4 GWh/year for cooling at the peninsular level. Nevertheless, what can be learned by thermal energy and the magnitude of this strategy for Spain is difficult to explain to non-experts. To have an idea of what can be expected by introducing this strategy, which is highly promoted by the European Commission [2; 4; 66], to the Spanish residential sector, Figure 8 presents an estimation of the saved natural gas volume during the winter season and a comparison of the total natural gas demand for Spanish households and small and medium-sized enterprises (SMEs) in 2022 (52.3 TWh [67]). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Building Type**} & **Floor Area** & \multicolumn{2}{c}{**Avg. Savings 1979–2019**} \\  & **(m\({}^{2}\))** & **(GWh/Year)** \\ \cline{2-3}  & **Heating** & **Cooling** \\ \hline Detached and Attached & 645,476,343 & 4.4 & 1.4 \\ Multifamily Buildings & 1,240,064,508 & 9.5 & 2.9 \\ \hline Detached and Semi-detached & 455,098,519 & 5.4 & 1.7 \\ Single-family Buildings & 794,588,763 & 6.7 & 2.4 \\ Buildings & 3,135,228,134 & 26.0 & 8.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Potential energy savings by extending to 1 \({}^{\circ}\)C the heating and the cooling set-point temperature in Spain. According to the latest survey of housing characteristics by the Spanish Statistical Office [41], only 80.6% of dwellings are equipped with a heating system, and 74.4% of these use a heating system based on natural gas or electricity, i.e., 60.0% of dwellings. In addition, 25.6% of the heated dwellings use oil, derivates, or other fuels (biomass, coal, etc.) and were excluded from the analysis of quantifying a fuel savings potential due to their irrelevance on the natural gas dependency. However, according to Building Technical Code Standard DB-HE0 [40], the Spanish dwellings are conditioned usually using three heating technologies, including a gas boiler (\(\eta\) = 0.92), an electric radiator (\(\eta\) = 1.00), and an air conditioner (split unit, COP = 2.90), where the usage percentage of these heating systems was extracted from the housing characteristics survey [41]. Considering the pointed value of gross savings of peninsular building stock in Table 8, it can be assumed that the gross savings will correspond proportionally to the floor area of dwellings with a heating system based on natural gas or electricity, i.e., 15.6 GWh/year on gross savings in heating demand based on electricity or natural gas. Therefore, the natural gas savings are given by defining a gas conversion factor for each energy vector, in the case of natural gas and the electricity generated by gas power plants (Table 9). The conversion factors were obtained considering the average gross calorific value (GVC) of natural gas in Spain for 2022 (11.6 kWh/m\({}^{3}\)(n) [67]), the weight of natural gas power plants in the peninsular power system in 2022 (60.6 TWh, i.e., 23.1% [68]), and the amount of natural gas used for electricity generation (138 TWh [67]). Figure 8: Annual potential natural gas savings per heating technology for extending by 1 \({}^{\circ}\)C the heating set-point temperature in Spain. Savings expressed in a normal cubic meter and percentage of total natural gas demand for households and SMEs in 2022.