Does a bucket of cold tap water in the middle of a room work to cool the room off?

Question

The water that comes out of our shower tap is always pretty cold, and I find myself taking several cold showers as the season gets warmer. I don't like using the air conditioner unless it's absolutely necessary, and water is free in our apartment.

Does maybe keeping a bucket of the cold water in my warm room a viable option for keeping the room cool? It seems as though it would absorb a good bit of the heat in the room, and then I can use that water to do the dishes later that night.

Answer 1

The temperature difference between cold water and a warm apartment will be small, probably no more than 30 degrees F.

A five gallon pail of water weighing about 41 pounds would absorb about 1200 BTU's if it took a single hour to warm up.

The rule of thumb for air conditioning is 12,000 BTU's per hour for a room of 400 square feet.

It would have very little effect.

You'd get more effect by rigging an evaporative cooler, sometimes called a "swamp cooler". Rig a towel or strips of cloth so that they wick water up from your bucket, and direct a fan toward them. The fan will evaporate the water, absorbing heat in the process. Your room humidity will be higher, but you'll be cooler.

Answer 2

Only if the room was an isolated system (no conduction, convection or radiation - i.e. no heat transfer occuring at all). This is impossible to find in day to day life (even a thermos flask has some heat transfer). The heat constantly entering the room will easily compensate for whatever heat is absorbed by the bucket of water.

Just to give you an idea - the amount of heat absorbed by a 5 gal bucket of water warming up from (say) 278 K to 298 K is about equal to the solar energy received on a small window in one hour on a typical spring or fall day. Of course, most of this is reflected back, but there are other sources of heat besides solar load.