Modeling approaches for the characterization of building thermal dynamics and model-based control: A case study

This article investigates two building thermal modeling approaches: (a) frequency response analysis and (b) a low-order gray-box resistance-capacitance thermal network. Frequency response analysis is a valuable tool for building dynamic response characterization and model-based control studies. Low-order models reflecting the dynamic response of the building are essential for practical model-based control. A case study used for investigation is conducted on a large environmental chamber with a high thermal capacity concrete floor. The chamber represents a typical building zone with a thermal capacity floor. A detailed frequency-domain model is first developed for the environmental chamber and verified with experimental measurements. In addition, three different low-order gray-box resistance-capacitance thermal network models (of the second, third, and fourth orders) are also developed for the environmental chamber. The effective parameters of the low-order models are obtained through an optimization routine. Then, from these detailed and low-order models, transfer functions linking indoor air temperature to the convective cooling/heating source are obtained and studied. The third- and fourth-order resistance-capacitance models are shown to represent with acceptable accuracy the thermal dynamics of a high thermal mass zone with a convective heating/cooling source. The presented investigation approach can be applicable to other types of zones and buildings.