Various industries have developed and implemented sophisticated control techniques, to control large multivariable systems, aimed at achieving specific performance constraints while seeking to minimize various cost functions. Until recently, there has been \/ery l i t t l e interest in developing and implementing such techniques to control building HVAC systems aimed at maintaining comfort conditions whicl minimizing the energy usage by the buildings. Individual HVAC subsystems and components were controlled for satisfactory operation. Interaction between the controls of various components and subsystems to minimize energy usage has been minimal or non-existent.

The objective of this research effort was to determine, for a representative building and HVAC system, the control strategies that would minimize energy usage or energy costs. The research examines the reduction in energy usage and costs that can be achieved when the controllable parameters in a building environmental system are controlled based on the knowledge of all system parameters, characteristics, loads and requirements, both at the present and, as applicable, into the future. The research included the composite modelling of a building, with a particular HVAC system. The model reflects the interrelation between comfort, the building structure and the various building HVAC sub-systems, components, control systems, and the energy requirements of the building. The scope of this research effort consisted of the simulation of a specific building to determine the effect of various control strategies on the building's energy usage. This included the development of a comprehensive simulation scheme to simulate the action of a control system that optimizes the building's energy usage.