## 3 Results
### Results from the Drying Simulations
#### 3.5.2 Results from the Drying Simulations
Apart from walls HI5 and HI7, the final MC for HI walls with high R\({}_{\rm{wb}}\)/R\({}_{\rm{t}}\) -ratios was slightly lower (9.3-9.7 wt-%) than in the BL walls. The final MC in walls HI9-11, with low R\({}_{\rm{wb}}\)/R\({}_{\rm{t}}\) -ratios, was higher than in the BL walls. This suggests that the U-value of the wall structure (Table A2: BL walls 0.21-0.36 W/m\({}^{2}\)K, HI walls 0.13 W/m\({}^{2}\)K) has an impact on the drying ability when the R\({}_{\rm{wb}}\)/R\({}_{\rm{t}}\) -ratio is low. In the summer-winter simulation, relative humidity declined under 85% in every wall during the first 30 days of simulation (Figure 11a,b). The RH levels were highest at the beginning of the simulation in walls BL4 and HI11, probably due to the Sd-value in the plywood (0.2-2.1 m). During winter, the relative humidity rose in walls with low thermal insulation outside the frame to a level of 85-90%. In wall BL2 relative humidity was at level 80-85 due to the highest U-value. The RH level in the HI walls with high R\({}_{\rm{wb}}\)/R\({}_{\rm{t}}\) -ratios continued to decline, even during winter. Walls HI4 and HI6 had the lowest RH during winter, resulting from the 100 mm wb-mineral wool. Walls HI11 and BL4 showed the highest mould index levels on the frame surface, reaching a level of 0.3-0.4 and on the rigid board  
Figure 12: **(a–d)** Mould index results; **(e)** weather conditions; **(f)** outdoor water vapor pressure during the drying simulations. Mold index was determined on the cold side of the frame **(a,b)** and on the warm side of the rigid board **(c,d)**. 0.5-0.6 (Figure 12a,c). For other walls, notable MI levels were observed only during winter. Particularly, walls BL1 and HI9 had MI values around 0.15 on the wood frame and 0.35 over the gypsum board. BL2 had notable MI value around 0.3 over the gypsum board. At the end of the simulation, the MI values were elevated on the wood frame of wall HI11 and on the rigid boards in walls HI9, HI11, BL1-2, and BL4. Despite the RH near 90% at the end of simulation, the MI level was low at wall BL3, probably due to the mould resistance of the FCB. In the autumn-spring simulation, wall BL2 had the highest drying rate during the first 50 days, after which wall HI4 dried the fastest, reaching a level of 8.8 wt-% at the end of the simulation (Figure 10c,d). Walls HI1-3 had final MC of 9.3-9.5 wt-% and the drying was as fast as in the summer-winter simulation. Walls HI6 and HI8 had also low final MC of 9.1-9.3 wt-%, which were slightly lower MC values compared to the summer-winter simulation. Highly insulated walls HI5, HI7, and HI9-11 had the lowest drying rates. The probable reasons for the lower drying rates in these walls are the increased insulation level from 300 mm to 450-650 mm (HI5, HI7) and the low \(\rm R_{wb}/R_{t}\) -ratios (HI9-11). At the end of the simulation drying increased in HI9 and HI7, walls with rising outdoor temperature resulting in final moisture contents of 11 wt-%. Walls HI10-11 did not reach the same way, which could result from the more vapor tight FCB and plywood boards, compared to the gypsum board. This is supported by the low reaction in MC with rising outdoor temperature in wall HI8 and the higher reactions in walls which had gypsum as wb-layer. These results imply that vapor open wb-layer allows the structure to dry faster when the outdoor temperature rises. Further, the low drying of extremely highly insulated wall HI7 in autumn (Figure 10d) and in winter (Figure 10b) indicates that the drying rates in extremely highly insulated structures are impaired by cold weather. One reason for this is that the temperature difference across the wb-layer during cold weather is smaller, with higher U-values of the structure. The lowest RH levels during the autumn-spring simulation were observed for walls HI1-4 and HI6 (Figure 11c,d). The remarkably low RH in wall HI4 originated from the highest \(\rm R_{wb}/R_{t}\) -ratio of all the walls. Walls HI5 and HI7 had higher RH values due to the lower \(\rm R_{wb}/R_{t}\) -ratio than in HI1-4 and HI6.