Thermodynamic analysis of ventilated façades under different wind conditions in summer period

Abstract

The main benefit attributed to opaque ventilated facades (OVF) is the reduction of cooling load for the building Heating Ventilation and Cooling (HVAC) achieved through ventilation led by natural convection in the ventilated chamber and the protection from solar radiation given by the outer layer of the façade.This research investigates the thermal behavior of an opaque naturally ventilated façade through Computation Fluid Dynamics (CFD) simulations during summer days. The CFD simulations have been performed in order to analyze the behavior of DSF components under different wind conditions in the summer period, utilizing the weather data of Catania city (Italy).For the different investigated scenarios, the authors have calculated the temperature and air velocity profiles inside the air gap of the façade, highlighting the different effects of buoyancy and wind forces.The results show that the wind forces in conjunction with the buoyancy forces affect significantly the performance of OVF components.Further, the reduction of the heat flux during the summer period has been evaluated by comparing the thermodynamic performance of a naturally ventilated and an unventilated façade with the same geometry and thermo-physical characteristics.The behavior of the naturally ventilated façade is an improvement in terms of passive cooling of the building compared to the non-ventilated façade since it allows the peak load to be shifted whilst offering energy savings in the range of 47% to 51% depending on climate.