## 5 Results
The first three days were selected for the measurement campaign and the measurement results were elaborated to calculate any sinusoidal variations of the external and internal surface temperatures, \(T_{si}\) and \(T_{se}\), respectively, as a function of time t with the equation:  
\[T_{s}(t)=\overline{T}_{s}+|T_{s}|\textit{cos}(\omega\textit{-}t+\psi) \tag{3}\]  
where \(\overline{T}_{s}\) is the average daily surface temperature; \(|T_{s}|\) is the daily amplitude of the surface temperature; \(\omega\) is the angular frequency (2\(\pi\)/24, with a time period of 24 h); \(t\) is the time in hours; \(\psi\) is the initial phase in hours. Figures 21 and 22 show comparisons between the measured and calculated (with Equation (3)) surface temperatures of a straw wall in Casa Cembo. A time shift, \(\Delta T\), of 19.3 h and an attenuation of the heat flow of 0.23 were also calculated by comparing the initial phases of the equations for \(T_{\text{si}}\) and \(T_{\text{se}}\). The same methodology had been applied and tested in previous research [17; 18; 19]. Figure 21: Casa Cembo straw wall: external surface temperatures (measured data indicated with the continuous line and calculated data with the dotted line). Figure 22: Casa Cembo straw wall: internal surface temperatures (measured data indicated with the continuous line and calculated data with the dotted line). Finally, the dynamic characteristics of the straw walls were calculated using the equivalent thermal conductivities of straw obtained from the two experimental campaigns; in particular, the periodic thermal transmittance \(Y_{IE}\), the decrement factor, and the time shift of the straw walls were calculated according to the EN ISO 13786:2017 standard. Low values of \(Y_{IE}\) and f and a high value of \(\Delta t\) can be observed in Table 4, which also shows out high thermal inertia and good thermal behavior for straw walls in warm climates. A similar time shift value, \(\Delta t\), to the one at 19.3 h calculated from the measurements can also be observed for Casa Cembo. The excellent thermal performance of the straw buildings, in particular for the inhabited residential building Casa Cembo, demonstrate why these buildings are starting to be successful, in particular in Northern Italy, as well as in France and other European countries. The analyzed straw wall has a thermal transmittance value, \(U\), that is well below the values required by the Italian laws (D.M. 26/6/2015 and subsequent amendments and additions) for the reference building and for existing retrofitted buildings. Thermal transmittance values of about 0.15 Wm\({}^{-2}\)K\({}^{-1}\) are in fact typical of nearly-zero-energy buildings (nZEB) in Italy [20]. Furthermore, as is already known, these buildings have excellent performance during summertime, as can be seen from the low periodic thermal transmittance values of \(Y_{IE}\) and decrement factor \(f\) and the high time shift value \(\Delta t\). It can be observed in Table 4 that the calculated periodic thermal transmittance value, \(Y_{IE}\), is much lower than the values required by the Italian laws (D.M. 26/6/2015 and subsequent amendments and additions), and that the time shift is higher than the values at 12 h, with a consequent reduction in the perceived thermal load peak due to the high daytime temperatures in summertime. These periodic thermal transmittance, time shift, and decrement factor values indicate that the considered straw structures have a high thermal inertia, with consequent positive effects on energy savings in both summer and in winter. The use of high inertia envelopes in the northern part of Italy may lead to energy savings of about 10% in wintertime and 20% in summertime [21; 22].