Analisi e ottimizzazione delle prestazioni termiche di una parete ventilata a struttura composita in legno e calcestruzzo mediante CFD

This study was carried out with the aim of evaluating the thermal performance of an innovative prefabricated ventilated façade system, formed by an internal lightweight structure and an external massive cladding. The façade is composed by an internal insulated timber-frame wall and an external concrete slab, separated by a ventilated air cavity. The objective of the study was to understand the façade thermal behaviour during summer and winter, as well as the influence of several external parameters, such as the weather, the typology of cavity air inlet, the cavity thickness, the materials roughness, and thermal inertia. Different simulations were carried out by using a CFD (Computational Fluid Dynamics) approach. At first, the simulations were carried out considering a steady state, which allowed to analyse the façade behaviour by changing some geometric parameters and model settings, without excessive computational effort. Then, dynamic simulations were carried out in order to consider the influence of the material’s thermal inertia on the façade behaviour. The results obtained by the dynamic simulations do not agree with those obtained by the steady ones, which are similar to the values given by the current Standards. Dynamic results highlight the positive contribution of the massive concrete slab in shifting the thermal wave during summer. Different results are found for the winter period, where the air ventilation has a negative effect on the façade energy performance. Since the data provided by the different simulations are not aligned, an experimental monitoring will be carried out on a real façade sample, in order to analyse the effective performances and validate the CFD model.