## 3 Results and Discussion
### Moisture Buffering Test  
Figure 4 shows the increases and decreases in the masses of individual samples in the absorption and desorption process and Figure 5 shows the MBVs calculated on the basis of these changes in relation to a given cycle. Considering the values shown in the graphs, it can be seen that only cycle 5 of Assembly A can be considered stable. In this case only, the change in the MBV between two consecutive cycles was 2.10%, which is less than 5%, indicating a state of equilibrium. In [34], it was shown that materials with small penetration depths require much longer times to achieve stable moisture-buffering cycles. Figure 4: Measured changes in mass of individual assemblies during the adsorption and desorption phases. Figure 5: Moisture buffer values of the assemblies versus cycle number. The penetration depth \(d_{p}\) is defined as the distance between the material surface and the depth where the amplitude of the vapour pressure variation is 1% of that on the surface [20; 35]. It is given by Equation (7):  
\[d_{p,1\%}=4.61\sqrt{\frac{D_{w}\cdot t_{p}}{\pi}}, \tag{7}\]  
where \(D_{w}\) is the moisture diffusivity of the material (m\({}^{2}\)/s), calculated as:  
\[D_{w}=\frac{\delta_{a}P_{sat}}{\xi\cdot\mu}, \tag{8}\]  
where \(\delta_{a}\) is the vapour permeability of air (kg/(m\(\cdot\)s\(\cdot\)Pa)), \(P_{sat}\) is the saturation vapour pressure (Pa), \(\xi\) is the moisture capacity (kg\(\cdot\)m\({}^{-3}\).%RH\({}^{-1}\)), \(\mu\) is the vapour resistance factor of the material and \(t_{p}\) = 24 h is the load cycling period. Comparing the tested assemblies based on the moisture penetration depth values (Table 3) for individual layers, it can be seen that Assembly A (except for the exterior layers of the gypsum fibreboard (3.6.3) with d\({}_{p,1\%}\) = 10.2 mm) was composed of mineral wool (4.12) with d\({}_{p,1\%}\) = 610.8 mm, and reached steady state fastest. Assembly B, with an internal layer of flexible wood fibre insulation (3.3.2) with a much lower moisture penetration depth of d\({}_{p,1\%}\) = 109.4 mm, did not reach steady state. Assemblies C and D, covered with several finishing layers with different values of moisture penetration depth, also did not achieve a stable moisture-buffering cycle. Therefore, we can expect Assembly D to be the last assembly to reach equilibrium, as it had the lowest penetration depth values for the individual layers. Figure 6 shows the MBVs for each sample, determined on the basis of the values recorded for the last (fifth) test cycle. The MBVs for absorption in all assembly samples were in the range 0.83-0.62 g\(\cdot\)m\({}^{-2}\).%RH\({}^{-1}\), while the MBVs for desorption were in the range 0.75-0.58 g\(\cdot\)m\({}^{-2}\).%RH\({}^{-1}\). Referring these results to the MBV classes shown in Figure 3, we can see that all the tested assemblies were characterized by a moderate predisposition to moisture buffering. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multirow{2}{*}{\(\xi\)} & \multicolumn{2}{c}{\(\delta_{a}\) (10\({}^{-11}\))} & \multirow{2}{*}{\(d_{p,1\%}\)} \\ \cline{3-3}  & & (kg\(\cdot\)m\({}^{-1}\).s\({}^{-1}\).Pa\({}^{-1}\)) & \\ \hline
2.2.4 earth plaster with straw & 0.035 & 1.11 & 18.9 \\
3.1 earthen adhesive & 0.003 & 0.28 & 174.3 \\
3.2 wood fibreboard—Pavaboard & 0.417 & 3.33 & 23.8 \\
3.3.2 flexible wood fibreboard—Pavaflex & 0.082 & 4.17 & 109.4 \\
3.6.3 gypsum fibreboard & 0.417 & 3.33 & 10.2 \\
4.12 mineral wool—ECOSE & 0.022 & 7.5 & 610.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Theoretical moisture penetration depth values. Figure 6: Moisture buffer values for individual assemblies. Comparing walls of similar construction, we see that Assembly B showed a slightly higher MBV than Assembly A, by 3.2% in the case of adsorption and by 3.4% in the case of desorption. As already mentioned, these two wall assemblies differed only in the type of internal insulation used.