Benefits

1. Change Behavior: When the user pays, they become more conscientious of their energy use and will try to conserve energy as extraneous use comes out their own pocket.
2. Managed Use: Having a card before being able to use is also a form of managed use, as only authorized personnel will possess a card and can use the a/c.
3. Time Based Tariff: Certain a/c types is not amenable to electricity metering as the electricity used is not directly measurable; in these cases, one can meter the elapsed time instead; but regardless of whether the purpose is for tariffing or to save energy, time based tariffing is the best solution.

Classroom Energy Saving Air Conditioning Control

During classes, the instructor inserts the card to enable the a/c; after class, the card is removed and power is cut off.