Wow - that's about 2-3 units a day just for a coolbox! I use about 3.5
units a day for everything - including a fullsize Bosch A-rated
fridge.

I think those coolboxes use Peltier cooling (a weird diode that gets
cool one side and hot the other when a current is passed through it).
Peltiers are very inefficient. http://en.wikipedia.org/wiki/Thermoe...ng#Performance
- says conventional refrigeration is many times more efficient.