of system uses electro-mechanical time clocks, to control various
functions according to time schedules. Ideally, these systems take into
account, holidays, weekends, daylight savings time, planned maintenance
and have an override feature.
and exterior lighting
Ventilation and exhaust fans
Thermostat setbacks and setforwards
systems provide for the control of multiple functions and more
sophisticated control of temperature setback/setforward. Inside and
outside air temperature are monitored and used accordingly to vary the
time of startup or setback of heating and/or air conditioning. These
systems achieve additional savings by using the least amount of energy
to produce comfortable conditions during occupancy.
on the complexity of the system, an economizer cycle can also be
incorporated. By controlling air dampers, this cycle brings outside air
into the cooling system whenever possible.
Demand Control Systems:
these systems, all of the functions of temperature/time optimization and
time clock controls are incorporated in a system that also controls
electricity demand by cycling pre-selected loads on and off as demand
approaches preset limits. Typical interruptible loads are heating,
ventilation and air conditioning (HVAC) systems; air compressor motors;
and manufacturing processes that can readily be interrupted or delayed.
In addition to generating energy savings by shutting off unnecessary
loads, these systems reduce monthly peak demand charges on electric
bills. Demand control systems provide for a large number of control and
monitoring points. They also incorporate features such as the ability to
monitor fire and burglar alarms, log internal environmental conditions,
record equipment running time and duty cycles, and track energy use.
business can benefit from the more sophisticated EMS. Weigh the cost
against potential savings before determining the type and level of
sophistication warranted. Before investing in a system, you should
conduct an in-depth analysis and inventory of your facility's lighting,
HVAC systems, and interruptible or deferrable loads. Other major factors
to consider include building type, size, nature of business, and number
of systems to be controlled.