posted originally from: AT:Hometech
Since you need your keycard when you leave the room, it guarantees that you switch off all your lights when you are not in the room. No card means no wasted electricity.
Another nice convenience was the 'Main Switch' located next to the bed. A quick tap of the button after a little bedtime reading and all the lights in the entire room are turned off and you stay cozy under the covers.
Building on this great post from Ryan, here's a note from the Green Home editors: we've seen variations of this idea implemented in the US two ways. First: a main switch that turns off all power to the house. This has been a favorite solution of people who want to avoid exposure to electromagnetic fields. Second: twin switches in a bedroom, so you can turn the lights off from the bed. Now that's green and romantic!