A frequency domain methodology for design and control of radiant floor systems

Radiant floor heating systems (RFH) offer significant potential for studying and developing energy flexibility strategies for buildings and their interaction with smart grids. Efficient design and operation of RFHs require several critical decisions on design and control variables to maintain comfortable thermal conditions in the space and floor surface temperatures within the recommended range. In this context, frequency domain techniques can assist in finding optimal design parameters prior to the performance of numerical finite difference simulations. This paper discusses the application of frequency domain techniques to the design and control of hydronic RFHs. Transfer function analysis is used to determine the optimal thickness of a concrete slab (including different types of concrete) that minimises air temperature fluctuations. Then, this paper discusses the use of a transfer function to calculate the delay between the radiant floor heating input and the zone air temperature. An application of this transfer function to a case study is presented.