A Numerical Model to evaluate the Thermal Behaviour of Active Transparent Facades

摘要

Active transparent facades are a type of building envelope more and more common in high-rise office buildings. Many designers have opted for a ventilated facade claiming that this technology is sustainable, reduces energy consumption and enhances indoor comfort conditions, but none of these issues has been so far clearly proved. Since 2000 at the Department of Energetics at the Politecnico di Torino a specific research activity on this topic has been carded out. The aim of the activity is to obtain, and to make available to the designers, experimental data and numerical models. In this paper a numerical model developed to simulate the thermal behaviour of mechanically ventilated active transparent facades and its validation by means of experimental data are presented. The model, developed in the Simulink/Matlab～environment, simulates the facade behaviour in transient conditions and provides, as output data, the temperature values of the different layers which compose the facade (glasses, shading devices and the air in the ventilated cavity) and the heat fluxes through each layer. The model has been validated comparing the calculated data with experimental data obtained at the TWINS test facility at the Politecnico di Torino. The model can simulate with a quite good accuracy the temperature values of the various layers. The simulation of the heat fluxes, on the contrary, is less accurate. The reason of this discrepancy, is probably due to the way the heat exchange with the indoor environment has been modelled, which is approximate for the specific configuration of the test facility.