Demand meters are a special type of meter typically found on larger commercial buildings and industrial facilities. The term "Demand" refers to the peak power requirement for a given time interval. Most utilities measure and subsequently invoice their "demand customers" for the highest 15 minute or 30 minute demand interval in a month. Each time the meter reader comes out to read the meter they reset the demand register for the next month. Demand meters, therefore, measure both energy consumption (k Wh) and peak power usage or demand (kW).