## 3 Results and Discussion
The EMC of the lower shingle layer was on average around 37% (SD = 14%) from the end of November 2017 until mid-April 2018 and then dropped to an average of 14% (SD = 2%) for the rest of the year. The risk for decay is high if the EMC is lastingly higher than 25% and the temperature stays above 5 \({}^{\circ}\)C [33]. From the end of November until mid-April, the model showed an EMC of more than 25% for both shingle layers, and the temperature was above 5 \({}^{\circ}\)C 20% of the time. For the rest of the year, the upper shingle layer's EMC bounced between 10% and 70%. The lower shingles' EMC varied between 10% and 20%. The analysis shows that, during the warm season, the upper shingles' EMC was repeatedly in a rot danger region. Consequently, strategies to lower the EMC (by improved dry-out) are advantageous, even if the improvement is low (Figure 9). According to the model applied, the lower shingles were not at risk of decay from midst of April until end of November. This temporal course of wood moisture is in good agreement with findings of [PERSON] and [PERSON] [33], albeit with lower precipitation; hence, a lower average moisture level was measured in this study. The lower shingle layer took up moisture from the streaming air in the ventilation layer 45% of the time (Figure 6). Whilst the mechanism of wetting and drying the lower shingle surface varied during the day (Figure 7), there were times, especially during the warm season, where the shingles were more severely wetted by the inflowing air. Focusing on the balance of moisture take-up and dry-out in Figure 6 throughout a year, more moisture was removed by ventilation than carried in. This is a strong argument for the ventilation of shingle layers and contradicts the findings of [PERSON] [20] stating that ventilation is not desirable a significant part of the year. If the eaves were permanently closed and the VASc was 0.06 m/s (thermal effects on the air speed neglected), the average MC of the lower shingle layer would be 24% (SD = 15%), 1% higher than with the open ventilation layer (Figure 9). EMC_w_u_m was not significantly affected by closing the ventilation gaps (Table 3). The roof construction was also evaluated without roof ventilation applying the attic climate (AtAT, AtAM) as a boundary condition below the shingles. The EMC of the lower shingle layer would be on average 26% (S = 18%), 3% higher than with the vented one and 2% higher than that with reduced ventilation. The moisture dry-out would be 17 kg/m\({}^{2}\) throughout the measuring period, 6 kg/m\({}^{2}\)  
Figure 9: Moisture content of the lower and upper shingle layer. less than with ventilation layer. The disadvantageous effects of reduced ventilation or an unvented construction were more pronounced during the winter months. Considering that ventilation of the shingle roofing is desirable when the lower shingle surface does not take up moisture from the ventilation air and that the air speed in the ventilation layer can be influenced by coverage on the eaves, technical solutions for steered ventilation are worthy of consideration [21]. This would require flaps at the eaves which are steered depending on the evaluation of air moisture, shingle temperature, amount of solar irradiation, and general weather conditions (e.g., snow on the roof). An estimation for the effects of this approach was conducted by closing the eaves in the model whenever it showed a negative moving average of 6 h dry-out rate (i.e. the air speed was set to 0.06 or 0.25 m/s, and the thermal effects were neglected). On average, the EMC of the lower shingle layer (EMC_w_opt_m) was 0.3% lower compared with EMC_w_m. In the current situation, this effect is minimal because it is superimposed by the effects of wetting due to rain. Nevertheless, this could be an interesting optimization of ventilated constructions which are not subjected to direct rain, such as ventilated facades. In this context, bio-actuators to steer the ventilation gaps, as proposed by [PERSON] and [PERSON] [34] or [PERSON] et al.