A simulation study on the performance of double skin façade through experimental design methods and analysis of variance

Systematic studies of the thermal fluid dynamic behaviour of building envelope systems through experiment analyses is limited by the relevant amount of time and high costs necessary to carry out a relevant number of tests covering all the possible configurations. Building simulation can be used as a tool to support the design of the experiments, i.e. to test, in a parametric way, different configurations to highlight the main trends, and therefore select the most relevant cases to be tested experimentally. Such a preliminary activity to maximize the effectiveness of the experiments may relates to both parametric analysis of indoor/outdoor boundary conditions, as well as parametric analysis of building envelope configurations. In the framework of a research project on double skin facade (DSF) systems where experiments are planned on a full-scale prototype, a model of a DSF is realized in a whole building energy software tool, and used to carry out a preliminary sensitivity analysis, by means of orthogonal array method and analysis of variance. Simulations were carried out in EnergyPlus, using the Airflow window module, and under steady-state conditions, a series of variables (cavity depth, venetian blinds tilt angle, airflow rate) have been investigated to assess their impact on the heat extract through the ventilation air and the total heat transmission between the outdoor and indoor environment. The results show that the main driver in the performance of DSF considering net heat rate transfer is the irradiation impinging on the façade in terms of boundary conditions, and coherently, the shading device is the feature that most affects the performance of the system among the characteristics of a DSF