Heterogeneous Water and Energy End-Uses and Implications for Residential Water and Energy Conservation and Management

Indoor water-use consumes energy to heat hot water. Indoor water- and energy-use vary significantly among households due to variable household water-use behaviors and varying ages and efficiencies of water appliances. Also, the energy consumed to heat water varies among households and depends on water heater efficiency, heater thermostat setup, percentage of hot water in the final used water, and the cold water intake temperature. This research considers behavioral and technological variability in household water-and-energy-use to better understand water and energy linkages and help utilities target water and energy conservation actions to customer and appliances within their homes that the most affect water-and-energy-use. We used a mathematical model to represent households' behavioral and technological variations to identify households' water and energy consumption and linkages. We used national detailed water consumption data for 400 single family households in 11 U.S. cities. Also we represented water heater types available in the U.S. and considered water heater intake cold water temperature across the U.S. We also represented the water heater thermostat temperature through information form 343 plumbing/heating contractor firms throughout the U.S. Research results show that the largest 14.6% of households use 30.5% and 33.1% of overall households' water and energy, respectively. We also found that water heater thermostat temperature and faucet flowrate are the most important factors that influence household energy-use. Turning down the water heater thermostat and adopting high-efficient faucets are the most effective actions to save household energy-use. The research findings can help water and energy utilities identify collaborative efforts to effectively save both water and energy.