## 3 Results and Discussion
In fact, while the rain immediately removes the products resulting from the attack of the original material, the condensation water, not normally being sufficient to flow on the surface, evaporates, leaving behind reaction products that can give rise to further destructive processes, eventually with disintegration of the surface area itself [8; 29]. Obviously, XPS observations of the cubic calcarenite after only 9 months of outdoor exposition do not allow to identify clearly the prevalent factors and/or their combined actions responsible for its decay. It was already possible, however, to notice that, while the first quarterly sampling showed some variation in the composition of the cube walls due to the wind blowing from the north, carrying additional elements (extra in the legends) mainly in EWS directions, later on, the XPS differentiation was no longer so evident, and gradually, the effects of the environmental interactions on the four walls could be considered averagely comparable. It was therefore decided to graphically represent the degradation trend of cubic calcarenite, expressed by the percentage intensity versus time of the component groups, averaged over the four walls, with the associated standard deviation. In the supplementary 'average' plots, Figure S2, two options are presented: in Figure S2a, the percentage of oxygen is retained to also control the variation of the average degree of hydration (i.e., the hydration de-hydration oscillations observed for the single walls), while, in Figure S2b, the oxygen is omitted to enlarge the scale and therefore better estimate the behavior of the component groups, the total area of the O1s region being implicitly considered as the stoichiometric sum of all the oxygenated compounds. The comparison of the two Figure S2 plots shows that the trend in the nine-month interval is indeed mainly characterized by the variations of the component groups, to be thus confirmed as the main indicators of degradation; therefore, the Figure S2b option was chosen to complete the plot of calcarenite decay over time to also simplify the processing and visualization of the larger dataset without considering the total oxygen percentage as an additional variable. The subsequent and final phases of the project specifically concerning the temporal monitoring of calcarenite by XPS were then considered in the following order:  
* XPS analysis of the old farm: sampling of'selected zones' differently degraded and colored As already specified in the Section 2, the samples were taken on the north east walls of the old building following the sampling sequences reported in Figure 2 and selecting the four specific zones, different in their appearance, therein indicated. The wide spectra of the four colored samples with associated peaks labeling and the curve-fitted C1s regions inserted are compared in Figure 5. The overall percentage composition derived by curve-fitting, without the total oxygen percentage, is reported in Table 2 using the same grouped components retrieved for the reference 0R sample, with no extra elements detected by XPS. Table 2 shows the curve-fitting results of the old building samples 1v-4v, in percentage form according to the Figure S2b option, and those correspondent to sample 0R of the new building added for comparison. We can now better judge the differences of the two references, 0R and a-1v, for the new and old buildings, respectively, qualitatively predicted by comparing their wide spectra in Figure 3. We can also extend the comparison to the remaining samples 2v-4v, all together representative of the old farm building, and derive some anticipations on the evolution of the surface compositions due to their very different aging times. Figure 5: Wide spectra with peaks labeling and inserted curve-fitted C1s of the powdered samples collected from the NE wall of the old farmhouse: (**a**) (**1v**) calcarenite-like; (**b**) (**2v**) efflorescence-like whitish; (**c**) (3v) green moss; (**d**) (**4v**) black crusts.