## 3 Results
### Quantitative Internal IRT Method  
Previous studies have demonstrated that highly insulated walls (U-value \(<\) 0.400 W/m\({}^{2}\)-K) and low heat capacity per unit of area (\(\sim\)200 kJ/m\({}^{2}\)-K) might be more difficult to evaluate [63]. However, prefabricated panels based on the passive house concept had not been assessed by means of quantitative internal _IRT_. As seen in Section 2.3, the external opaque walls of the detached house were designed practically equal to the building envelopes of the experimental mock-up. In fact, the theoretical thermal transmittances were 0.245 and 0.233 W/m\({}^{2}\)-K, respectively. Concerning post-construction evaluation \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & & \multicolumn{2}{c}{**Experimental Mock-UP**} & \multicolumn{2}{c}{**Detached House**} \\ \hline \begin{tabular}{c} **Number of** \\ **Cyole** **Evaluated** \\ \end{tabular} & \begin{tabular}{c} **Duration of the** \\ **Analysis Period** \\ **(Days)** \\ \end{tabular} & **Analysis Period** & \begin{tabular}{c} **\(\mathbf{U_{m-HFM}}\)** \\ **between Periods of** \\ **Analysis (\%)** \\ \end{tabular} & \
\begin{tabular}{c} **Deviation of \(\mathbf{U_{m-HFM}}\)** \\ **between Periods of** \\ **Analysis (\%)** \\ \end{tabular} &
\begin{tabular}{c} **\(\mathbf{U_{m-HFM}}\)** \\ **between Periods of** \\ **Analysis (\%)** \\ \end{tabular} \\ \hline \multirow{2}{*}{3 (72 h)} & \multirow{2}{*}{2} & Initial test period & 2.34 & 2.3 & 2.34 & 1.5 \\ \cline{2-6}  & & Final test period & 2.40 & 2.37 & 2.37 \\ \hline \multirow{2}{*}{4 (96 h)} & \multirow{2}{*}{2} & Initial test period & 2.34 & 0.8 & 2.34 & 0.6 \\ \cline{2-6}  & & Final test period & 2.33 & 2.35 & 2.35 & 1.1 \\ \hline \multirow{2}{*}{5 (120 h)} & \multirow{2}{*}{3} & Initial test period & 2.36 & 0.3 & 2.35 & 1.1 \\ \cline{2-6}  & & Final test period & 2.37 & 2.37 & 2.37 & 1.7 \\ \hline \multirow{2}{*}{6 (144 h)} & \multirow{2}{*}{4} & Initial test period & 2.33 & 2.4 & 2.34 & 1.7 \\ \cline{2-6}  & & Final test period & 2.39 & 2.2 & 2.38 & 2.0 \\ \hline \multirow{2}{*}{7 (168 h)} & \multirow{2}{*}{4} & Initial test period & 2.33 & 2.2 & 2.34 & 2.0 \\ \cline{2-6}  & & Final test period & 2.39 & 2.39 & 2.39 & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Deviation of U-values between the initial and final analysis period for each test duration for both the experimental mock-up and the detached house, using the _HFM_ average method. Figure 7: Coefficient of variation of both the experimental mock-up and the detached house, using the HFM average method. by thermography, the results revealed that the gap between the design nominal data and the real thermal performance was found to be 5% in both case studies (Table 7 and Figure 8). Hence, the proposed facade-building system of the mock-up fulfilled the expected thermal behavior in the real built environment. Despite this, a greater fluctuation of the measured thermal transmittance was observed for the detached house (Figure 8). From the analysis of variability, it can be extrapolated that standard deviations were slightly similar (0.021 W/m\({}^{2}\)-K for W1 and 0.024 W/m\({}^{2}\)-K for W2) and the coefficients of variation (\(CV\)) were less than 10%. However, the plot of confidence intervals at 95% for _IRT_ measurements (Figure 9) shows some differences between _WI_ and _W2_. It should be noted that a box plot indicates if a statistical datum is normally distributed (the median of the data is located in the middle of the box, and the quartiles are symmetric) or skewed. (the median of the data is closer to the bottom or to the top of the box, and the distribution of instantaneous measurements is asymmetric). In the case of the experimental mock-up, the minimum and maximum U-values were 0.202 and 0.324 W/m\({}^{2}\)-K (including outliers). A positive skew was also observed, since most of the instantaneous measurements fell in the upper quartile.