Saving energy in your home is laudable, but, apart from a less startling electricity bill, how can you tell how much you’re using? The Wattson has a wireless transmitter that clips to one of the cables running from your electricity meter to your fusebox, and the unit then gives you a live view of how much power you’re using. It glows anything between calming blue to angry red, depending on how much electricity is being consumed, and displays either the total in Watts or the amount of money you’re spending. Electricity tariffs can be updated by plugging the device into your PC, and you can even graph your energy-saving performance online. We had no connection problems in our tests, but the manufacturer claims a maximum range of 30m indoors.