Energy Management Systems (EMS) are special-purpose computerized control systems, programmed to operate building lighting and HVAC equipment such as chillers, fans, boilers, pumps, dampers, valves, and motors. They can vary in complexity from a single function controller that performs the simple control of one piece of equipment, to a system with a distributed architecture, in which controllers throughout the building operate local control loops, supervised by a central or 'host' computer.

Energy conservation potential is related to the functions the EMS performs, such as programmed start and stop, optimal start and stop, duty cycling, economizer control, HVAC operation and demand limiting. The EMS savings potential varies widely, due to the range of energy management functions and basecase control strategies. One study estimated HVAC savings at 5% to 20% above those available with a 7-day clock. Most EMS functions will not affect consumer utility. Duty cycling, optimum start and stop, and demand limiting may in some cases cause occupant discomfort. The EMS has a beneficial effect in reducing building operation personnel requirements and providing fire protection and security functions. In an EMS survey, the average energy cost savings was about 15%.

The technology is rapidly developing. Installation costs are highly dependent on the degree of complexity of the system, and the number of input and output points. System commissioning and operator training are essential.

Source: Greenhouse Gas Technology Information Exchange