Energy refurbishment of an Office Building by addition of a second skin: Improvement of thermal behavior, energy performance and possible conversion by PV

The energy retrofit of the building stock is a central issue in the view of reduction of energy consumption and climate change. The energy efficiency measure proposed in this study provides first the application of a double skin façade and the evaluation of the positive and negative effects due to this measure; then, in a second phase, to counteract the possible negative effects, a control logic for opening windows of the double skin façade is defined. These windows respond dynamically to variation of external conditions by allowing an air flow from the cavity to the internal environment in winter period and from the cavity to the external environment in summer period. The building under investigation belongs to the University of Naples Federico II and it is dedicated to offices. The building geometry and the characterization of building envelope and systems installed are realized with the graphical software DesignBuilder®, while EnergyPlus software is used for the dynamic simulation of the building thermal and energy performance. The control logic for the opening of the windows is defined through the module Airflow Network of EnergyPlus. The energy benefit in terms of reduction of primary energy demand for the space heating and cooling reaches values of 44.4% and 8.4%, respectively. Finally, semi-transparent a-Si photovoltaic modules (efficiency of 4 %) are integrated into the façade. When they cover the half area of the external façade, there is a production of 5120 kWh/year and a saving of 11.2% in electricity consumption.