The Water Heating Calculator allows users to determine the energy and greenhouse gas emissions embedded in a unit of hot water for a specific location in the United States. Because the temperature of water entering a home can vary significantly depending on local conditions, the amount of energy required to heat a unit of water can differ from city to city. All other factors being equal, the cooler the inlet water the more energy required to heat the water to a desired temperature. This calculator is designed for nonprofit organizations or utilities interested in determining the end-use energy savings that can be achieved in their community by reducing demand for hot water. This information is best applied in conjunction with data on the volume of water saved by end-use related to water conservation efforts.

Only two pieces of information are needed to run The Water Heating Calculator: the zip code and water heater temperature settings of the study area. For water heater temperatures settings, a default value of 140° F is provided although actual temperature settings may vary. A typical range for residential water heating settings is between 120° F and 140° F. After entering the zip code you wish to assess, users should enter a value that best reflects the average water heater setting of the community.

To use this tool, data is entered on the left-hand side of the screen and the results display to the right of the white divider line. The data and assumptions behind this tool can be viewed by clicking on the “Assumptions” tab in the bottom left corner of the workbook. Please note that these models are designed for educational purposes and are not intended to provide a comprehensive analysis of a given scenario.

River Network would like to thank Pacific Institute for providing the data on inlet water temperature by zip code.