## 3 Results
### Occupant Surveys  
The actual operating conditions in residential buildings are usually not consistent with the prescribed calculations in compliance with the regulations. For example, in Greece, the calculations according to the national EPBD regulations are performed for almost continuous occupancy and use of space heating (i.e., 18 h per day), with an indoor setpoint temperature at 20 \({}^{\circ}\)C for the whole floor area of the dwelling. On the other hand, a national survey [6] documented that the majority of the dwellings used heating for less than 8 h per day (i.e., 71% of SFHs and 82% of MFHs), while only 11% of SFHs and 8% of MFHs operated heating continuously. A staggering 31% of the dwellings were forced to switch off their central heating. Furthermore, only a very small percentage heated their entire dwelling (7% of SFHs and 17% of MFHs). Figure 6: Actual primary energy use intensity for normal climate conditions in the audited residential buildings presented for the different typologies (i.e., single-family houses (SFHs) and multi-family houses (MFHs)) for the different construction periods (before and after 1980). The results from the survey managed to capture similar information. Over time, the campaign [13] managed to collect responses from several hundred participants, providing results that, overall, were in general agreement with the corresponding information from the national survey. This gives some confidence that the collected data from the questionnaire provided representative results. The data presented in this work refers to 129 dwellings (of which 39.5% were SFHs and 60.5% were MFHs) that were also audited. The representative results are summarized in Figure 7. The adaptation factors were calculated as weighted averages of _f(Actual/Calculated)_, and they are summarized in Table 2 for the different building typologies (i.e., single- and multi-family houses) and for both SFHs and MFHs that were recognized as \"all residential\" buildings. Depending on the parameter, the actual operating conditions were compared with the assumed values of the normative calculations. Specific examples are provided in the following discussion. **Operating Hours**. Most of the dwellings used their space heating systems for only 3-4 h (Figure 7a). The main reason driving this usage was the need to reduce the operational costs. Continuous heating was used in less than 14% of the SFHs and 4% of the MFHs, while those that used the systems for more than 16 h resembled the assumed period for the normative calculations. The vast majority (i.e., 65% of SFHs and 81% of MFHs) used their space heating systems for less than 8 h per day. About 31% of the SFHs and 40% of the MFHs were forced to switch off their central heating and use local heating systems. The weighted average for the operating hours was 7.6 h in SFHs, only 3.1 h in MFHs and 7.1 h when considering all residential buildings. The corresponding adaptation factors in \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Building Type** & **Operating Hours** & **Isolated Areas** & **Indoor Setpoint** \\ \hline SFH & 0.423 & 0.882 & 0.881 \\ MFH & 0.171 & 0.881 & 0.843 \\ All residential & 0.396 & 0.882 & 0.853 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Weighted average adaptation factors (_f_) for the building types: single-family houses (SFHs), multi-family houses (MFHs) and all residential buildings. Figure 7: Actual operating conditions in single-family houses (SFHs) (upper row) and multi-family houses (MFHs) (lower row), showing the (**a**) average daily space heating hours, (**b**) non-heated (isolated) floor areas and (**c**) indoor temperature setpoints. The gray shaded areas identify the assumed values used in the national EPBD calculations. Table 2 were then calculated as the ratio of the actual values for each building type to the assumed one for the normative calculations (i.e., 18 h in this case). **Isolated Areas**. Heating the entire dwelling was practiced in less than half of the houses (i.e., 47% of SFHs and 45% of MFHs (Figure 7b)).