Improved Performance of a PV Integrated Ventilated Facade at an Existing nZEB

Ventilated facades are among the existing measures to reduce the energy demand in buildings. The combination of this passive heating and cooling strategy with photovoltaics (PV) can drive new buildings towards the current European targets near or even to net zero energy Buildings (nZEB). The present work studies the thermal behavior of the PV integrated ventilated facade applied in the nZEB known as LUCIA (acronym in Spanish for University Centre to Launch Applied Research) at the University of Valladolid, Spain. The aim is to evaluate the interest of recirculating indoor air within the facade during winter, as an alternative to the present preferred operating mode during the target season, in which the facade acts as further insulation. First, the radiant properties of the PV facade are measured to use the values in a mathematical model that describes the behavior of the ventilated facade in its current operating mode in winter. Then, the solar radiation available, the air-dry bulb temperatures indoors, outdoors and inside the ventilated facade are monitored to obtain experimental data to validate the model. The results show that air recirculation can entail favorable heat gains during 10% of winter, being this alternative preferable to the present operating mode when outdoor temperatures are over 18.4 degrees C.