## 4 Conclusions  
This paper aimed to identify the importance of the mortar layers (renders and plasters) on the water content level of masonry walls for two types of climates--temperate (Lisbon, PT, and San Francisco, USA) and cold climates (Zurich, CH, and Essen, DE). Secondly, this influence was also assessed in terms of the variation in the thermal transmitances, which varied through time due to the influence of the water content on the thermal conductivity. Finally, it aimed to determine if current mortar can withstand future moisture loads by carrying out simulations for the most demanding wind-driven rain (WDR) spells. The assessment of the hygrothermal performance of the masonry walls was studied by means of using a complex HAM simulation software (WUFI(r)Pro). Overall, it was concluded that temperate climates attain higher annual and hourly WDR values and have more favourable conditions for drying than cold climates. In temperate climates, a render is responsible for a less pronounced variation in the water content in the solid brick layer, while a plaster generates an increase in the water content in the solid brick layer. A wall coated on both surfaces has a similar behaviour to a wall coated just on the exterior surface but with slightly higher values. The more impermeable the mortar is to moisture, the larger the magnitude of these behaviours. In cold climates, the walls have the same behaviours as previously described for temperate climates, except for the fact that for rendered cases, the highest water contents are not obtained with the less impermeable mortar due to the wind-driven rain spells' magnitude. It was also observed that the application of a render layer has a greater impact on the moisture behaviour of the solid brick layer in temperate climates than for cold climates due to their better drying conditions. Although rendered and plastered walls have the same thermal transmittance in steady-state conditions, in transient conditions, their values can be quite different. The application of a render layer originates the decrease in the differences between the steady-state and transient thermal transmitances (for temperate climates), and the application of a plaster layer originates an increase (for both types of climates). The magnitude of these behaviours increases according to the moisture transport properties of the applied mortar layer. In conclusion, the moisture behaviour of the solid brick layer, and, consequently, its tempera \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Scenario**} & \multirow{2}{*}{**Spell**} & \multirow{2}{*}{**Size of Spell (h)**} & \multirow{2}{*}{**Rain Spell**} & \multirow{2}{*}{**Eq. Water**} & \multicolumn{2}{c}{**WDR Reach**} \\  & & & **(L/(m2h))** & & **Content (kg/m2)** & & **Water** \\  & & & & & **Content (kg/m3)** & \\ \hline \multirow{3}{*}{NP} & no. 1 & 196 & 27.0 & 3.3–14.8 & 110 & 17.9 \\ \cline{2-6}  & no. 2 & 24 & 24.2 & 6.9–16.0 & 110 & 43.5 \\ \cline{2-6}  & no. 3 & 235 & 18.4 & 9.1–15.8 & 200 & 8.9 \\ \hline \multirow{3}{*}{NF–RCP4.5} & no. 1 & 203 & 33.8 & 3.3–15.6 & 114 & 18.0 \\ \cline{2-6}  & no. 2 & 25 & 25.1 & 5.5–14.9 & 107 & 12.1 \\ \hline \multirow{3}{*}{FF–RCP4.5} & no. 1 & 73 & 16.3 & 3.5–14.2 & 94 & 18.4 \\ \cline{2-6}  & no. 2 & 65 & 22.0 & 1.8–11.6 & 88 & 6.9 \\ \cline{2-6}  & no. 3 & 257 & 31.0 & 5.4–14.7 & 179 & 6.4 \\ \hline \multirow{3}{*}{NF–RCP8.5} & no. 1 & 304 & 33.1 & 3.0–13.6 & 129 & 17.0 \\ \cline{2-6}  & no. 2 & 94 & 17.2 & 3.4–13.6 & 94 & 13.4 \\ \hline \multirow{3}{*}{FF–RCP8.5} & no. 1 & 362 & 31.0 & 3.0–13.0 & 114 & 14.5 \\ \cline{2-6}  & no. 2 & 133 & 16.2 & 7.4–12.6 & 94 & 36.5 \\ \cline{1-1} \cline{2-6}  & no. 3 & 127 & 23.0 & 1.7–10.0 & 125 & 6.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Overview of the spells assessed in Sections 3.3.2–3.3.4 that influence the moisture content of the selected assembly. ture and the thermal transmittance of the wall, greatly depend on the moisture transport properties of the coating layers, as well as on the exterior ambience conditions.