Low-order model for the simulation of a building and its heating system

Signifirant progress has been made in recent years on the development of modular and generic simulation programs for investigating the thermal behaviour of buildings and associated HVAC plant and controls. However, many of these programs are inflexible for the specific analysis of HVAC plant and control systems over short time scales. The nature of this inflexibility is discussed and a remedy is sought through the development of a low-order lumped-capacity thermal model of a building space. This is expressed as a linear time-invariant state-space description. A non-linear dynamic model of a hot water heating system with feedback control has been added and results under open-loop conditions are presented. The model has the advantage of simplicity and computational efficiency. Results are compared with field-monitored data obtained from a building in use and an excellent agreement between the two is demonstrated, though this comparison is restricted to a north-facing building space with high thermal capacity.