## 3 Results and Discussion
[35], could find a meaningful future application. If the attic is inhabited and heated, moisture diffusion and convection might interfere with the mechanisms studied in this project. The construction would be equipped with a vapour retarder under the insulation, but the moisture flow through leakages may be significant [36]. Presumably, the moisture transport from the inside to the outside would be minimal because of vapour barriers applied on the inner side of the roof construction. The heat flow from the inside might slightly raise surface temperatures in the ventilation layer, which would diminish the condensation problems. This effect may also be minimal, because constructions tend to be very well insulated. Nevertheless, these multifactorial processes should be studied in further research. In the current study, a roof of western orientation was studied. The unmodified roof construction was evaluated for the other cardinal directions as well, changing the boundary conditions in the software. In Figure 9 and Table 3, one can see that the modelled EMC of the lower shingle layer was highest on a north-facing roof with an average of 26% (SD = 15%) and lowest on a south-facing roof with an average of 20% (SD = 10%). The differences were most significant during the cold time of the year (end of November until mid-April). This findings are in good agreement with a study focusing on the fungal decay of wood in different microclimates showing that all studied wood species have a higher risk of decay in shaded areas [37]. Focusing on the dry-out rate, it was highest with a north-facing orientation (26 kg/m\({}^{2}\)) and lowest with a south-facing orientation (20 kg/m\({}^{2}\)). As both roof orientations were flown through with the same air in the model, it follows that the south-facing roof's lower shingle layer was dried up to the top more efficiently, because there was a higher drying potential of the sun. Evaluating the surface temperature on the shingles' exterior surface, the average temperature accounted for 13.3 \({}^{\circ}\)C (SD = 11.9) east, 14.1 \({}^{\circ}\)C (SD = 12.5) south, 12.6 \({}^{\circ}\)C (SD = 12.0) west, and 11.6 \({}^{\circ}\)C (SD = 10.8) north. Hence, it can be concluded that efficient ventilation is more important on roofs with less sun exposition. In Figure 6, one can see that the dry-out of the shingles' lower surface increased from the south, followed by east, west, and north, and this was indirectly proportional to the radiation of sunlight, confirming this finding. This was also seen when comparing the average moisture content of a ventilated roof and one with closed eaves (Table 3). Whilst the average EMC was unchanged for the south-facing roof, the EMC of a roof with reduced ventilation on the northern side was on average 1% higher. The modelled effects of cardinal orientation on the wood moisture of shingles need to be verified in further in situ measurements in subsequent investigations. Furthermore, it will be necessary to evaluate other effects such as cracks as a result of wood shrinkage on the shingle surface, which could cause significant local changes of moisture conditions after several years of exposure [38], and such as ascending forces when air is heated up in sun-exposed ventilation layers.