Optimization can take on many meanings when applied to different problems and applications, ranging from ad hoc parameter variation to high-powered numerical analysis. One area that has received a significant amount of attention is the optimization of building design and operation, usually regarding certain aspects of energy usage, thermal performance or occupant comfort. Building control systems can have an important contribution to these performance characteristics, and are prime candidates for application of optimization techniques. This paper discusses the role of optimization in the design of building control systems, and outlines approaches and methods which can be useful for improving performance based on the needs and goals of the project. Two examples are presented to illustrate the methods and results.