If you are male and unmarried, you may not know what I'm talking about. If you are female, or male and married, then you know that keeping the shower clean is a matter of grave concern. One of the tools in our shower-cleaning arsenal is a shower squeegee. This is a smaller plastic version of the tool professional window washers use to clean windows, and is used in much the same way to skim the water off the walls of your shower.
The theory behind the shower squeegee is that if your shower isn't wet, then mold and mildew will not grow on it nearly so quickly. I cannot testify to the accuracy of this theory but I can testify to how fervently my wife believes in this theory. So the other day, when I was using the squeegee after my shower and pondering the sheer injustice of my situation, I discovered that the shower squeegee is actually an energy-saving device and immediately felt better about keeping the shower clean.
How, you ask, can keeping the shower dry keep down my utility bills? Well it works like this — during the summertime, anything that keeps humidity out of the air makes your air conditioner work more efficiently. Taking short, cool showers is very useful, of course, but keeping the water that lingers after a shower from evaporating into the air also helps keep humidity down.
A related tip--if you put a lid on your shower, you keep the humidity from escaping into the house, and you keep the shower warm and comfortable. Keeping the humidity in the shower stall might seem a disaster for mold, etc., but in fact it's the opposite. With the lid, the overall humidity in the bathroom stays low, so once you open the shower door, the shower dries out faster.
This also makes it more comfortable to turn off the water while you are soaping up--it's a triple energy win:
-Less humidity for the A/C to take out.
-Warmer in the shower so you don't need to set the water temperature as high.
-Warmer in the shower so it's comfortable to turn the water off.
And as a bonus you have less mold/mildew, both in the shower and in the bathroom as a whole.
See the instructable instructions on this and the New Zealand "Showerdome" commercial product , and the Sunfrost page explaining this.