It used to be that most buildings relied on pneumatic, electric, and/or electronic controls systems to handle basic building functions such as hvac. While these control systems are still used in many applications, the trend over the last two decades has been to replace these systems with direct digital control (ddc).
Ddc systems are computer-based control systems that can integrate with building automation systems, and also control other building functions such as hvac, lighting, security, elevators, etc. In addition to providing tighter environmental control, ddc systems can monitor energy consumption and diagnose system problems faster — all from a remote location.