DE-05-01-3 - National Impact of Hot Water Distribution System Losses in Residences PDF

This paper provides an estimate of the scope of losses of energy and water caused by the poor design and installation of hot water distribution systems found in many residential buildings. The purpose of this estimate is to assess whether or not the waste of energy, water, and time associated with waiting for hot water to arrive at fixtures in a home is large enough to warrant further study and possible remedial actions.

The approach uses an estimate of average water wasted down the drain per household determined by three different techniques. It also accounts for important ancillary effects, such as increases in tank setpoint temperature to overcome temperature drop in the distribution system. The losses of multi-family recirculation systems are also considered. The resulting national estimate, which combines water, waste water, and in-building energy losses, shows that these losses are very large, resulting in nearly one-half trillion gallons of water wasted annually, with total annual cost impacts around $11 billion. Moreover, these numbers appear to be growing at a rate of more than one percent per year. Even if the waste is only half that presented in this paper, this is a problem worthy of further investigation.