Numerical and experimental study of the dynamic thermal resistance of ventilated air-spaces behind passive and active façades

The variation of the thermo-hydrodynamic behavior airflow in ventilated cavity behind external claddings a wall structure could potentially affect overall thermal resistance entire structure. Although impact an enclosed air-space on total R-value assembly has been thoroughly investigated literature, it not addressed for cavity. In present study, as first step, plausible definitions to determine transient conditions are described. As second dynamic naturally air-spaces passive (i.e., brick and fiber cement) active BIPV) facades studied using two approaches. approach, 2-D numerical model validated against measurements is employed compute air gap under different conditions. Accordingly, cladding type, seasonal variation, thickness, presence reflective insulation change analyzed. in-field performed test facility experimentally examine contribution results obtained from both approaches compared with design values calculated based ISO 6946:2017 9869–1:2014 standards. reveal that during day be captured simulations. It shown daily averaged reach up 47 times higher than BIPV façade. experimental confirm converge steady-state value after certain duration time following requirements provided standards, which practically used code-compliant analysis. also observed act layer some solid materials assembly.