AT-15-021 -- Estimating Daily Domestic Hot-Water Use in North American Homes ✓ Most Recent

Water heating in the U.S. is a major component of totalenergy consumption in buildings, accounting for approximately18% of total consumption in the residential sector (EIA 2010).While there are many factors influencing hot-water energy use(location, fuel, combustion and heating efficiency, and standbylosses), the actual volume of daily water to be heated is a fundamentalquantity for any reasonable estimate of hot-water energyuse. This study uses measured annual hot-water use in variousNorth American climates to evaluate hot-water use in homes.Thefindings show that the quantity of hot-water use is correlated mostclosely to the mains water temperatures and the occupant demographicsof the homes with 70% of the available measurementdataexplainedwhenoccupantdemographicsarewellknown.Thestudy proposes a new methodology for estimating the quantitiesof hot-water use in homes as a function of climate location andoccupancy demographics, segregating machine hot-water use,fixture hot-water use, and distribution system hot-water waste.