## 2 Methodology
### Hygrothermal Tests  
Two experiments were performed on the coated wall assembly samples, using a CTS climatic test chamber, where it is possible to control the internal parameters in the temperature range from +10 \({}^{\circ}\)C to +95 \({}^{\circ}\)C and in the humidity range from 10% to 98%. The lateral surfaces of the tested samples were tightly sealed with aluminium foil on four sides, thus creating a barrier against the penetration of water vapour. Other surfaces (upper and lower) were left uncovered to expose them to moisture absorption and desorption, representing an internal wall between two environments. The first test, known as the sorption/desorption kinetics test, was performed using the following protocol. Firstly, the samples were preconditioned at 23 \({}^{\circ}\)C and 50% RH, and then the relative humidity was increased to 80% and the samples were kept in this environment for 324 h. After this time, the relative humidity was decreased to 50%. During the test, the temperature was kept constant at 23 \({}^{\circ}\)C and the samples were weighed. The sorption kinetics values were calculated as a function of mass gain/loss over time. The moisture content variation (\(\Delta\)MC) was calculated using Equation (5):  
\[\Delta\text{MC}=\frac{W_{80\%/50\%}-W_{50\%}}{W_{50\%}}\times 100\%, \tag{5}\]  
where \(W_{80\%/50\%}\) is the weight at 80% or 50% RH during the mass change and \(W_{50\%}\) is the constant weight of the preconditioned sample at 50% RH. Because several samples were weighed at the same time, the measurements were carried out outside the chamber, in less than 2 min. The short exposure time of the samples to different humidity conditions does not significantly interfere with the results. This was confirmed by [PERSON] [12], who compared the results obtained from mass measurements of samples carried out outside the chamber with those from continuous measurements taking place directly in the chamber. The second test, i.e., the MBV test, determined the MBV in terms of water-vapour adsorption and desorption in response to cyclic humidity variation. A number of methods are available to determine the moisture buffer value of building materials, such as the Nordtest method [10], the Japanese standards [28], the ISO standard [29], the method proposed by [PERSON] [30] and the ultimate moisture buffer value concept [31]. Each of the methods vary in terms of the procedure of the test, the time steps used, the humidity level and the sample sizes, but all use the same principle of exposing samples to different RH variations and recording the mass changes within the samples. The methodology used in this study differs from the Nordtest method in the range of measurements recorded, the cycling of RH levels and the time steps. According to the Nordtest method, the materials are exposed to cyclic step-changes that alternate levels of relative humidity from 75% for 8 h to 33% for 16 h. The duration of the entire cycle is 24 h. During the test the temperature is held constant at 23 \({}^{\circ}\)C. In this research different levels of humidity and time steps was chosen: 50% for 12 h and 80% for 12 h, according with German industry standard [32]. When assessing the behaviour of assemblies in rooms with high occupation, or bathrooms where there are many moisture sources and the ventilation level is often inadequate, especially in the summer, the proposed approach responds better to these conditions. Firstly, the samples were conditioned at 23 \({}^{\circ}\)C and 50% humidity, until the mass change of the specimen between two consecutive measurement was below 1% of the total mass. This state was considered to represent equilibrium with the environment. Then, the samples were exposed to a series of step changes in relative humidity between two levels, in cycles of 24 h (12 h at 80% RH and 12 h at 50% RH), at 23 \({}^{\circ}\)C. Five cycles were carried out with a total test time of 120 h. Switching between the humidity values was performed manually, according to the adopted load diagram (12/12 h).