Estimating Daily Domestic Hot-Water Use In North American Homes

Water heating in the U.S. is a major component of total energy 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 stand by losses), the actual volume of daily water to be heated is a fundamental quantity for any reasonable estimate of hot-water energy use. This study uses measured annual hot-water use in various North American climates to evaluate hot-water use in homes. The findings show that the quantity of hot-water use is correlated most closely to the mains water temperatures and the occupant demographics of the homes with 70% of the available measurement data explained when occupant demographics are well known. The study proposes a new methodology for estimating the quantities of hot-water use in homes as a function of climate location and occupancy demographics, segregating machine hot-water use, fixture hot-water use, and distribution system hot-water waste