Frequency domain and finite difference modeling of ventilated concrete slabs and comparison with field measurements: Part 2. Application

This paper is the second of two papers that present techniques and guidelines for frequency response (FR) and lumped-parameter finite difference (LPFD) approaches for the thermal modeling of building-integrated thermal energy storage (BITES) systems. To assist the thermal analysis and control of active BITES systems, development of FR and LPFD models are presented in this two-part paper. Modeling methodology and techniques are presented in paper Part 1 using ventilated concrete slabs (VCS) for demonstration. In this part, the methodology is applied to two types of VCS. The modeling results from different FR and explicit LPFD models with different time steps and discretization schemes are presented. The results are compared to each other, and with field-measured data from a solar demonstration house with a VCS. Simulation results show that time step of half an hour for FR models results in less than 3% error in thermal performance. For LPFD models, discretization with Biot number smaller than 0.5 can reduce error to about 5%.