When entering the rooms, the guests have to insert the room card into the Energy Saving Switch to turn on the lightning system. When he/she is leaving the room, the guest takes the Room Card out; then the power supply will be shut off by the Energy Saving Switch about 15 seconds later. The delay function is very important in the Energy Saving Switch, without it, the guests have to leave the room in the dark. The consumption of the illumination system in each hotel room is about 2000 watt.