This is one of my pet peeves.
Water saving water closets of 1.6 gallon per flush are required, water savers in the shower heads are required, yet there is no water saving requirement for water usage / time to get hot water to any given water faucet.
Sanitary guidelines require washing your hands with hot water and soap after flushing the 1.6 gallon per flush commode, yet there is nothing that adresses the fact that it can take 15-30 minutes and gallons and gallons of water just to get the hot water to the facuet so you can wash your hands in hot water with soap.
There are two choices, one was already mentioned: designing for and installing a hot water circulation pump. The second, and possibly more energy efficient, is to install a second water heater in the houses with long hot water supply lines.
If a builder used just slightly more ingenuity, they could centrally locate the water heater on one side of the house between the laundry, bathroom and kitchen,without compromising the requirements for the T&P valve discharge line to gravity drain to the exterior, AND locate a second one over by the master bathroom and the large spa tub.
Now you do not have the energy waste for the hot water circulation pump or the water and energy waste for running excess water through the water heater just to get hot water over long distances.
[Edited by Jerry Peck on 14 October 2000]