Often showers take 15 minutes or more while shaving or when especially sleepy. As a deterrent to being late and to conserve water I sometimes do the ultra-fast shower.
Ultra-fast shower: wet for 10 seconds at faucet, water off, then lather up everywhere, then shower on for a rinse. There are two drawbacks to this method which I hate: waiting for the water to heat up and that while lathering the air in the shower is cold.
Ideally, the air in the shower and the tile floor would both be around 100°F for comfort. A button would douse the user for ten seconds, then stop. After lathering or even shaving in the warm, moist air environment, a regular shower would rinse off in about 30s to a minute.
I want to apply this Ultra-fast pre-heated shower environment to existing shower installations, with dual tub/showers OR standalone shower stalls. I hope to change the way people think of getting clean, and reducing heated water consumption in showers by 85% or so, in my case.