## 2 Materials and Methods
### Case Studies  
The following procedure was devised to illustrate the applicability of in situ measurement techniques to determine the thermal transmittance of highly insulated facades. Firstly, the experimental mock-up (\(A\) = 12 m\({}^{2}\)) with controlled climatic conditions was erected in January 2017, in order to determine good practices in the monitoring process of constructive solutions in the Mediterranean climate (Figure 3). In this way, it was possible to test a specimen that could ensure four of the six principles that define a passive house (PH): a high level of insulation, a minimum number of thermal bridges, highly efficient windows, and a high level of airtightness. The facade construction system consisted of a galvanized steel structure with prefabricated panels whose internal configuration was (from outside to inside) as follows: mortar, lightweight concrete, polyisocyanurate insulation (PIR), non-ventilated air cavity, lightweight concrete, and gypsum plaster. The main thermo-physical parameters are reported in detail in Table 2. Once the mock-up was erected, installations and finishes were carefully incorporated.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **N\#** & \begin{tabular}{c} **Material** \\ **Layer** \\ \end{tabular} & \begin{tabular}{c} \(\Delta x_{i}\) \\ **(m)** \\ \end{tabular} & \begin{tabular}{c} \(\lambda_{i}\) \\ **[W/(m-K]]** \\ \end{tabular} & \begin{tabular}{c} \(R_{t,i}\) \\ **[m\({}^{2}\).K/W]** \\ \end{tabular} & \begin{tabular}{c} **L** \\ **(m)** \\ \end{tabular} & \
\begin{tabular}{c} \(\boldsymbol{U_{t}}\) \\ **[W/(m\({}^{2}\).K]**]** \\ \end{tabular} \\ \hline \multirow{4}{*}{
\begin{tabular}{c} **W1** \\ **Experimental** \\ **mock-up** \\ \end{tabular} } & 1 & Mortar & 0.015 & 0.550 & 0.027 & \multirow{4}{*}{2.64} & \multirow{4}{*}{0.245} \\  & 2 & Lightweight concrete & 0.060 & 0.160 & 0.375 & \\ \cline{1-1}  & 3 & PIR insulation & 0.080 & 0.028 & 2.857 & \\ \cline{1-1}  & 4 & Non-ventilated air cavity & 0.060 & — & 0.180 & \\ \cline{1-1}  & 5 & Lightweight concrete & 0.070 & 0.160 & 0.438 & \\ \cline{1-1}  & 6 & Cypsum plaster & 0.015 & 0.430 & 0.035 & \\ \hline \hline \end{tabular}  
* \(\Delta x_{i}\) thickness of the layer; \(\lambda_{i}\), thermal conductivity of the layer; \(R_{t,i}\), theoretical thermal resistance of the layer; L, height of the wall; \(U_{t}\), theoretical thermal transmittance of the building facade.  
\end{table}
Table 2: Configuration and technical features of the experimental mock-up (from outside to inside).  
Figure 2: View of the measuring equipment used during the acquisition-of-data process.  
Having implemented the _HFM_ and quantitative _IRT_ as a tool of decision-making in terms of built quality, and taking into account the conclusions of the preliminary study, the wall was reproduced in the real built environment in February 2019 (Figure 4). The differences between specimens _W1_ (experimental mock-up) and _W2_ (detached house) were given by the thickness and the thermal resistance of the material layers. The technical features are shown below (Table 3). The detached house (\(A=322\) m\({}^{2}\)) was also characterized by high efficient doors (\(U_{D}=0.93\) W/m\({}^{2}\)-K) and low-emissivity triple-glazing windows (\(U_{W}=0.99\) W/m\({}^{2}\)-K) that allowed us to achieve an air renovation <0.56 h\({}^{-1}\). As regards the building facilities, the mechanical ventilation was focused on a heat-recovery system (model ComfoAir Q450, Zehnder) with an efficiency of 95%, and the indoor environmental conditions were guaranteed by an aerothermal equipment of 6 kW (model HPSU, RotEX).