Terms We Use
Following are key terms that can help you understand electric demand:

• Kilowatt (kW)—Rate of using electricity (Demand).
  Example: Ten 100-watt lamps consume electricity at the rate of 1,000 watts, or 1 kilowatt (kW).



• Kilowatt-Hour (kWh)—Electrical energy actually used (Energy).
  Example: Ten 100-watt lamps, when on for one hour, consume 1 kilowatt-hour (kWh) (i.e., 10 lamps x 100 watts x 1 hour = 1 kWh).



• Load Factor—A measure of energy use equal to the ratio of total kilowatt-hours (kWh) used in a given time period divided by the peak kilowatt (kW) use during that time, multiplied by the hours in the time period.
  Example: (Actual kWh used) / (peak kW x Time)
  
  Load factor expresses how well or poorly a given electric system is being utilized. Electricity users strive for a better load factor, or the most efficient usage of their installed electric equipment. The closer to 1 a given load factor, the better the system's efficiency.

Defining Demand Customers
We install a demand meter for customers who exceed a pre-determined level of energy usage (kWh). These levels are defined in our Service Rates area.

Understanding Demand Metering
Much like your car's odometer records accumulate mileage, electric meters record consumption (kWh). Electric demand meters function like your speedometer—with an important difference.

A demand meter's needle advances as electricity consumption increases, just as your speedometer needle advances as your speed increases in a car. When you stop the car, the needle moves back to zero, regardless of the highest miles per hour reached on the trip. Unlike a speedometer needle, demand meters record the highest average kilowatts reached and maintained within an interval period (i.e. 5 min., 15 min.)

For example, if within one billing cycle your demand reaches 50 kW and stays there for 15 minutes, the meter needle remains at 50 kW unless or until your demand exceeds that level. If your demand later reaches 55 kW and stays there for 15 minutes, the needle will then stay at 55. The new index point is maintained, even when you are using electricity at below 55 kW, until the meter reader comes to record the demand and resets the meter back to zero.

Some intermittently used equipment can be operated using various interlocks and automatic controlling devices. Since each kW demand saved is a savings on your monthly bill, looking into these types of devices makes good sense.

Saving Energy with Demand Control
There are many ways to manage demand, ranging from manual controls and timeclocks to sophisticated automatic units that program buildings and processes. For the average commercial building, the best control over electrical demand may not be in the electric system, but in the building itself. Good thermal design—tight construction, good window design and appropriately sized ventilation systems—is the key to limiting demand and avoiding demand charges. It creates less need for heat and cooling, allowing you to select smaller, more cost-effective equipment.