## 3 Results and Discussion
Figure 5: Various temperatures and dry-out rates of the lower shingle layer in spring 2018. Figure 6: Integral dry-out for normal and reduced ventilation and dry-out rate. The surface temperature on the shingles' bottom surface fell below the dew-point temperature of the inflowing air 6.3% of the measuring time, which was also mentioned to an even larger extent by [PERSON] et al. [19]. This corresponds to 180 h of potential condensation. The time when the shingles' lower side temperature was lower than the dew-point temperature was concentrated 99% in one half of the year (1 November to 1 May). During this time, 12% of the time condensation conditions were detected. How much the dew point temperature was undercut (SST-VDT) was strongly indirectly correlated (\(R=-0.91\)) with the VAM. In the beginning of April 2018 in the morning hours, SST fell strongest below VDT throughout the whole measuring time (Figure 7). The shingles did not take up a lot of moisture in this time (shown by predominantly positive values of Dry-out rate_w_m), because the vapour pressure (AVP, VVP) was low during that time, meaning that the air carried a low amount of water (Figure 3). Consequently, it was not the condensation of moisture that caused the most moisture uptake on the shingles' lower surface, but moist inflowing air in the warm season (shown in Figure 6 during time intervals with a low slope of the cumulated dry-out curve). The surface temperature of the shingles on the side of the ventilation space (SST) was well correlated with the air temperature in the ventilation layer (VAT) (\(R=0.99\)) and was on average 0.7 \({}^{\circ}\)C lower than VAT. This was probably caused by long-wave radiation of the shingles to the sky [18], heat flow from the inside to the ventilation air (AtAT was on average 0.8 \({}^{\circ}\)C higher than VAT), and snow, partly lying on the shingles in the beginning of 2018. Snowfall was recorded on 40 days from the start of the measurements until the end of March 2018 and was a reason for the stronger deviations of SST from VAT during the winter months (Figure 3). The air speed in the ventilation layer in the centre (VASc) showed a minimum value of 0 m/s and a maximum of 1.03 m/s and was well correlated (\(R=0.99\)) with the air speed at the border (VASb). The average air speed in the ventilation centre was 0.19 m/s. The variability was high with a SD  
Figure 7: Various temperatures and dry-out rates of the lower shingle layer in the beginning of March 2018.  
of 0.14 m/s. During the first measuring period P1 (ventilation open), the average of the air speed accounted for 0.12 m/s; during P2 (western eave closed), the average of the air speed accounted for 0.06 m/s; during P3 (ventilation open), the average of the air speed accounted for 0.12 m/s; during P4 (both opposite eaves closed), the average of the air speed accounted for 0.06 m/s; during P5 (ventilation open), the average of the air speed accounted for 0.25 m/s (Figure 8). The air speed at the border of the ventilation field was on average insignificantly lower (on average 0.003 m/s) than in the center. It could be shown that, by closing one eave (P2), the average air speed in the ventilation layer could be reduced by 50%. VASc was positively correlated with AAT (\(R\) = 0.76) and AtAT (0.82) meaning that higher air temperatures resulted in a higher air flow in the ventilation layer. In the summer half-year, the average air speed in the ventilation layer was twice as high as in the winter when the eaves were open, which supports this conclusion. Comparing P2 with the western eave open and P4 with both opposite eaves closed, the air speed was the same, but the average of AAT was 12.2 \({}^{\circ}\)C higher in P4 than in P2, while the wind conditions were comparable (average wind speed P2 1.2 m/s, P4 0.9 m/s; average wind direction P2 205\({}^{\circ}\), P4 190\({}^{\circ}\)) and there was a positive correlation of AAT and VASc. This suggests that there was additional air-flow hindrance when both eaves were closed.