On Saturday 4 November we invite you to flick the switch and commence generation of one of the world’s largest and most overlooked power sources – not Megawatts but Negawatts! Negawatts are created by harnessing people power or, more specifically, people's power of restraint.

If every house saves just a few Watts, that's one less new power station that we need to build. And if every house saves 100W through simple actions like switching off a light that's not really needed, or being careful not to overfill the kettle, we’d save not one power station but several.

So have you the energy for it? Here's 'watt' to do on the day. . .