Energy Management & Control Systems
One of the most effective ways to automate building energy systems and to
reduce operating costs is through Energy Management and Control Systems (EMCSs).
However, some of these are nothing more than glorified time clocks that turn
things on during occupied periods and off during unoccupied periods. Most zones
of the building should have automatic local control and only have monitoring
that lets the building operator troubleshoot and anticipate problems. Always keep
the systems as simple as possible and avoid the natural lure of systems with
pretty pictures and lots of instrumentation. If you can't be sure that the
monitoring will let you operate the building better, don't install it.
EMCSs capable of performing building control are broadly classified into three
levels of sophistication. While the obvious HVAC applications predominate,
they are far from the only applications involved. They can be used for fan,
pump, escalator, and lighting control.
Level I EMC Systems: These systems are essentially electronic timeclocks that perform a single function and are usually located on or in close proximity to the equipment being controlled. The control functions include:
- on and off time
- automatic temperature set-back/set-up,
- dry bulb economizer,
- enthalpy controllers,
- single and multizone systems,
- chiller energy management controllers.
Level II EMC Systems: These systems generally provide remote control and perform more than one function typified by duty-cycling and optimized start-stop. Some of the better applications include:
- demand controllers (to reduce peak electrical demand),
- multiload system programmers (to schedule multiple chillers on and off line),
- multifunction programmable controllers.
Level III EMC Systems: These are the central building control systems with the fancy control screen graphics. The central console monitors and analyzes remote data logging equipment. These systems are usually appropriate when the facility comprises many buildings or a single high-rise with a central plant and several remote mechanical
equipment rooms.
Typical optimizing functions include, but are not limited to:
- economizer cycle,
- hot/cold deck temperature reset,
- discharge air temperature reset.
- chilled water reset,
- outside air schedule reset,
- start/ stop optimization,
- air distribution optimization,
- chiller plant optimization,
- boiler plant optimization.
Operational Functions
Operational functions are primarily those associated with monitoring and alarm:
- chiller profile generation,
- boiler profile generation,
- maintenance management.
