## 3 Results and Discussion
### Assemblies Hygrothermal Assessment: Current Climates
#### 3.2.1 Water Content within Assemblies
This is due to the wind-driven rain magnitude, which in this type of climate is almost never sufficient for the case of lime renders to surpass the lime-cement case. The cement-rendered case behaviour is quite different from the other cases due to its lower moisture transport properties. A wall coated on both surfaces has a similar behaviour to that of a rendered wall. It is possible to understand the importance of the magnitude of wind-driven rain spells by comparing the behaviour of the rendered walls in cold and temperate climates. Therefore, the following three paragraphs only refer to the behaviour of rendered cases in two climates (Zurich and Lisbon) for the first simulation year. Initially, the same behaviour concerning the water contents (i.e., highest values of water content correspond to the case with the most moisture-impermeable mortar--cement--and the lowest values to the case with the less moisture-impermeable mortar--time) occurs in both climates (Figure 10 for Zurich and Figure 11b for Lisbon). However, when the wall faces a wind-driven rain spell with sufficient magnitude, the after-effect of this solicitation is different considering the type of climate. In both climates, the less impermeable mortar (lime) attains the highest water content values. However, in Zurich, the amount of moisture absorbed by the exterior surface is not enough to compensate for the drying of the wall, and, shortly after, the lime-rendered case is surpassed by the lime-cement-rendered case (Figure 10). This does not occur in Lisbon, since the amount of moisture on the exterior surface is so substantial that it originates a very large difference between both cases, preventing the lime-cement case from surpassing the lime case (Figure 11). The cement-rendered case is a special situation, since the amount of moisture that reaches the solid brick layer is very low due to its low moisture transport properties. Furthermore, the amount of incident rain on a wall in Zurich is so low that it causes the cement-rendered case to have very different behaviour from the other two rendered cases. Figure 9: Water content variation in the solid brick layer for the standard case (SC) and rendered cases in Zurich, ZR (**a**), and Essen, ES (**b**). LR—Lime, LCR—Lime-cement, and CR—cement renders. The alternation of the case with the highest water content value is due to the change in the wall's main source of moisture. When the wall was not yet subjected to the wind-driven rain spell, the main source of moisture is the interior ambience or interstitial condensation. Therefore, the more impermeable the render is to moisture, the greater the opposition for moisture to be transported across the wall will be, thus increasing the amount of moisture stored at the interface. When the wind-driven rain spell occurs, the less impermeable the render is to moisture, the higher will be the amount of moisture that penetrates into the mortar (since it offers a lower resistance to moisture transport), and, consequently, a higher value of water content is reached in the solid brick layer. The latter behaviour has a much higher magnitude than the former. Figure 12 shows that the application of a render layer has a greater effect in temperate climates than in cold climates. For uncoated solid brick walls, Lisbon's values are much higher than Zurich's, namely in the wall's wetting phase (Figure 12, in square dot). However, due to the application of the render layer, this difference decreases substantially, and in some cases, it can even cause an exchange of the climate with the highest values. This fact is quite obvious if we compare the relationship between the extreme cases for both climates, i.e., the standard case and the cement-rendered case.