A lumped-parameter model of a smart ventilation unit for Nearly Zero Energy Buildings

In the present work, a simple model of a ventilation unit used for residential purposes is proposed, which was developed by means of MATLAB Simulink and the Simscape toolbox, also including the Moist Air and Two-Phase fluid libraries. This study falls in the realm of air conditioning in nearly Zero Energy Buildings. The model presented here is focused mostly on the aeraulic system. A parametric analysis of various installation conditions was conducted to assess and enhance the combined heat pump and the air distribution system performance, under various operating conditions. Therefore, the overall approach included several parameters, such as outdoor and indoor air temperature, humidity, static pressure, pressure drop in the intake and the distribution ducts, and filter fouling. The model serves as a predictive tool to evaluate the effectiveness of the whole system, in both design and off-design conditions; notably, critical conditions are emphasized, which are associated to severe fouling conditions, making the use of an additional fan ineffective.