Energy Management Systems

Energy management systems (EMS) conserve energy by adjusting operating hours and/or cycling equipment. EMS devices range from simple on/off time clocks controlling a single system, to sophisticated computerized controls that manage all the energy-consuming systems in a building.

Single function EMS units can cost as little as $100, while complex systems can cost more that $100,000.

EMS cost savings vary according to the load being controlled. Typically, they can help reduce energy costs 10 to 30 percent, with payback periods usually less than two years.

Types of EMS Systems

Time-of-Day Scheduling:
This type 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.

They usually control

• Interior and exterior lighting
• Security lighting
• Space heating systems
• Air conditioning
• Ventilation and exhaust fans
• Thermostat setbacks and setforwards

Temperature/Time Optimization:
These 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.

Depending 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:
With 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.

Applications

Not every 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.

Let Us Help

PSNH Account Executives can help you identify EMS opportunities and recommend the appropriate technology to control your electrical loads. Our state-of-the-art meters can measure electrical loads, equipment duty cycles, and other measurements necessary to evaluate the feasibility of an EMS.