Basis of Guidelines for Structural Design and Thermal Assessment of Buildings with Hybrid CLT-Glass Elements

Facade elements are known to represent a building component with multiple performance parameters to satisfy. Among others, “advanced facades” take advantage from hybrid solutions, like the assemblage of laminated materials. In addition to enhanced mechanical properties that are typical of optimally composed hybrid structural components, these systems are energy efficient, durable and offer lightening comfort and optimal thermal performance. This is the case of the structural solution developed in joint research efforts of University of Zagreb and University of Ljubljana, within the Croatian VETROLIGNUM project. The design concept involves the mechanical interaction of timber and glass load-bearing members, without sealing or glued glass-to-timber surfaces. Laminated glass infilled timber frames are in fact recognized as a new generation of structural members with relevant load-carrying capacity (and especially the enhancement of earthquake resistance of framed systems), but also energy-efficient and cost-effective solutions. In this paper, brief guidelines for the optimal structural design of glass infilled Cross-Laminated Timber (CLT) framed systems are presented. A special focus is then dedicated to the thermal performance assessment of these innovative CLT-glass facade modules under ordinary operational conditions. Finite Element numerical models of single elements are developed to reproduce a full-size mock-up building. The actual thermal performance is thus carried out with the support of continuous ambient records. The numerical results show that the CLT-glass composite facade system can be efficient and offer stable performances, in line with national and European standards requirements.