## 2 Materials and Methods
The Italian national regulation (DM 26/06/2015 [24]) provides a thermal transmittance U limit for retrofitting: In this case study, the limit is 0.28 Wm\({}^{-2}\) K\({}^{-1}\) from 1 January, 2021, given the thermal zone (E) where the mockup is located. The aim of this study is to compare the behavior of the building envelope with different external insulating layers. To this purpose, three wall types were defined with the following features:  
* Wall 0: Wall constructed from LWC (Type 0);
* Wall 1: Wall 0 plus insulation made of a cork based lightweight plaster (Type 1) and finishing smoother (Type 3) to protect the external insulating linings;
* Wall 2: Wall 0 plus insulation made of an XPS panel (Type 2) and finishing smoother (Type 3) to protect the external insulating linings. Wall 0 offers a thermal transmittance U equal to 0.36 Wm\({}^{-2}\) K\({}^{-1}\), which is not sufficient to respect the Italian regulation. Therefore, in order to fulfil the national limit, two different types of insulating materials were chosen, thus, a transmittance value of 0.26 and 0.20 Wm\({}^{-2}\) K\({}^{-1}\) were reached for Wall 1 and Wall 2, respectively. The thermo-physical properties of the layer walls are presented in Table 3.  
The experimental mockup is located in Fabriano, in central Italy (latitude 43.329\({}^{\circ}\), longitude 12.939\({}^{\circ}\), altitude of 325 m, and 2198\({}^{\circ}\)days). Fabriano is characterized by a warm and temperate climate, classified as Cfa according to the Koppen-Geiger classification. A rural area without any other building or vegetation nearby was chosen to eliminate any possible influence on the performance of the mockup. Monitoring campaigns were carried out during summer 2018 (specifically 15 June-5 September) and between spring and summer 2019 (specifically 27 May-16 July). The measurement campaigns were carried out on a cubic prototype building positioned at an angle of 44\({}^{\circ}\) from the South and featured with 70 cm thick walls, which provide a high thermal capacity. Thus, the total volume was 27 m\({}^{3}\) and the internal volume was only 4.1 m\({}^{3}\). The mockup is equipped with no heating or cooling system, therefore no internal temperature control is allowed. In order not to have solar radiation heat gain from transparent elements, no window is present; moreover, there is only one square opening (\(60\times 60\) cm) on the Northwest-exposed facade, which was closed during monitoring campaigns with a polystyrene panel to reduce thermal dissipations. The research project was carried out with the following steps:  
* Site preparation to verify the necessary tools to install the mockup;
* Plan of sensor network and control systems;
* Detailed on site monitoring to analyze the summer dynamic behavior of the experimental case study; \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Wall 0** & **Wall 1** & **Wall 2** \\ \hline Total thickness t & (cm) & 70 & 74.5 & 78.5 \\ Position of insulating material & & diffuse & external & external \\ Insulating thickness t\({}_{\text{i}}\) & (cm) & - & 4 & 8 \\
**Characteristics of the entire wall** & & & & \\ Thermal resistance R & (m\({}^{2}\) K W\({}^{-1}\)) & 2.76 & 3.88 & 5.02 \\ Thermal transmittance U & (W m\({}^{-2}\) K\({}^{-1}\)) & 0.36 & 0.26 & 0.20 \\ External areal heat capacity K\({}_{2}\) & (k) m\({}^{-2}\) K\({}^{-1}\)) & 58.3 & 15.6 & 9.3 \\ Areal heat capacity K & (k) m\({}^{-2}\) K\({}^{-1}\)) & 840 & 862 & 853 \\
**Characteristics of single insulating layer** & & & & \\ Thermal resistance Ri & (m\({}^{2}\) K W\({}^{-1}\)) & 2.59 & 1.08 & 2.22 \\ Areal heat capacity Ki & (k) m\({}^{-2}\) K\({}^{-1}\)) & 840 & 12.32 & 4.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Thermal characteristics of external walls. * Data collection and analysis of results.