# Thermal and Energy-Efficiency Assessment of Hybrid CLT-glass Facade Elements
## 3 Mock-up Building  
Given the design challenges and requirements summarized in Section 2, this paper experimentally and numerically explores the thermal performance and energy efficiency of a full-size building  
Figure 3: Example of meteorological data (selection of outdoor temperature acquisitions) from the Municipality of Zagreb (Faculty of Civil Engineering). prototype that is currently under investigation within the framework of the VETROLIGNNUM project. A mock-up building prototype including hybrid CLT-glass facade elements (herein called the \"Live-Lab\" facility) was constructed at the beginning of 2018 and is still collecting relevant data. The facility (Figure 4) consists of a full-sized single space characterized by plan dimensions B = 3.22 m \(\times\) W = 2.80 m, with H = 2.8 m as the height. The 3D building is located on the roof of a single-story building (not accessible to the public) at the University of Zagreb, Faculty of Civil Engineering. The transversal envelopes of the facility (West and East sides) currently consist of CLT-glass modules, as seen in Figure 2. However, the prototype is assembled in such a way that it allows removal of the CLT-glass facade elements (for future re-use in different mock-up configurations) and the introduction of solid timber walls (Figure 4a). The geometry and detailing of the main building components were defined on the basis of preliminary calculations for the expected load-bearing capacity under ordinary loads. This choice resulted in the use of prefabricated panels for the wooden houses to obtain a lightweight framework system. In Figure 5, a typical cross-section of the walls, the floor, and the roof panels is shown. The constituent layers include:  
* 18 mm thick Oriented-Strand Board (OSB) panels (125 \(\times\) 2500 mm their size) on both the internal and external sides;
* 2  
Figure 4: Assembly process for the Live-Lab facility at the University of Zagreb (2018): **(a)** the general concept; **(b)** CLT–glass facade elements and **(c)** roof installation. * 200 mm wide timber frame members (KVH solid structural timber members marked by C24 resistance class (spruce) according to EN 338 provisions [42] dried to up to 18% humidity);
* A mineral wool insulation infill (NaturBoard VENTI mineral wool boards (600 \(\times\) 1000 mm) by KNAUF Insulation [43]). A steam dam was also installed between the inner OSB and timber frame members (Delta-Dawi GP [44]). Finally, in contrast to Figure 5 and the common practice for buildings, additional polystyrene insulation layers (on the exterior side) or plasterboard foils (on the inner side) were omitted due to their lack of aesthetic requirements. Accordingly, an impregnating finisher was used on the OSB surfaces to ensure their water resistance. The South longitudinal wall was erected with a single full-size panel. On the opposite side, the North wall was composed of two partitions to account for a possible door (Figure 4a). Two adjacent panels, mechanically interconnected, were used to realize the floor. For the single-pitch roof, timber beams were used to support the ceiling panels. Globally, the 3D assembly was thus characterized by the geometrical surface parameters reported in Tables 1 and 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**Exterior Walls of the Heated Section with Openings (m2)**} \\ \hline North & East & South & West \\
10.98 & 9.82 & 10.98 & 9.82 \\ \hline \multicolumn{4}{c}{**Heated Exterior Walls without Openings (m2)**} \\ \hline North & East & South & West \\
10.98 & 0.00 & 9.38 & 0.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Building elements of the zone on the boundary heated outside.