Originally posted by
I never thought of it that way, but I've also never tried it. So then the frozen milk jug is a much better idea because it can be refrozen over and over again?
Freezing something over and over isn't as efficient as using an air conditioner. If you're using that method repeatedly during a heat wave, you'll actually end up heating your house rather than cooling it. A refrigerator cools its content by exchanging heat with the radiator coils on its back; this process requires work so the fridge will generate some extra heat to do it. All the heat you take away from the water to turn it into ice gets dissipated in your kitchen. Most air conditioners, on the other hand, dissipate the heat outdoors.
If you happen to have a milk jug already frozen from some time when you didn't need cooling, then go ahead and use it. If you're using a bowl of ice, keep in mind that all that ice adds to your indoor humidity; that can be a good thing if you're in a dry climate but an air conditioner would reduce your humidity.