The application of an Energy Management and Control System (EMCS) combines the arts and sciences of system hardware and software applications. The decisions that face one starting on a system design include answers to such questions as:

1. How much control will the system have over the HVAC and electrical systems?
2. Should the control be distributed from the Central Processing Unit (CPU) to smaller units, called Satellite Processing Units (SPU), throughout the project?
3. If the system is to control the dampers and valves directly, how extensive should the backup be and should the fail-safe switchover be manual or automatic?
4. What is the smallest item to be monitored and controlled by the system?