Heaters unnecessary
The point is not how efficient a given appliance is at heating a patio, but how pointless that is. What is the carbon footprint of a warm sweater, or a blanket? It is easy to say a device is efficient at doing its job without asking whether that job is unnecessary or the wrong solution to a problem.
If you are cold out of doors in the winter, may I suggest you either go back in doors or put on some more suitable clothing - rather than making a disproportionately large impact on the environment because you can't be bothered to wear a sweater?
Biting the hand that feeds IT
