There are some interesting consequences of this. I heard about a "Earth Hour" or something, a campaign for people to turn off their lights (or something) for a

There are some interesting consequences of this. I heard about a "Earth Hour" or something, a campaign for people to turn off their lights (or something) for a hour (or minute) to use less power. However unless the National Grid can plan for how many people will do it (nigh on impossible), they'll probably wind up wasting power, and more people can be used preparing for everyone to turn things back on, resulting in Earth Hour/Minute actually use more power than if they'd done nothing.