Select a Scenario and Press Calculate Technology Warming Potential
plot to be generated:
alternative to heating water with a heat pump water heater:
     fuel type:
     storage type:
source of electricity:
choose CH4 emission reference or enter CH4 emission rates:
     CH4 emission reference:
     CH4 emission rates:
          full lifecycle emission (%):
          local distribution loss (%):
choose efficiency assumption or enter efficiency factors (EF):
     efficiency assumption:
     heat pump water heater EF:
     alternative water heater EF:
     power plant efficiency (%):
if desired, enter emission factors from user's own scenario:
     heating water with a heat pump water heater:  
          CH4 emission (kg/GJ):  
          CO2 emission (kg/GJ):  
     heating water with an alternative water heater:  
          CH4 emission (kg/GJ):  
          CO2 emission (kg/GJ):  
if emission on x axis, time (year):
calculation method:
implementation scenario:
This tool can be used to evaluate the greenhouse gas footprint of heating water with a heat pump water heater relative to the most commonly used domestic hot water systems: natural gas and electric resistance water heaters with and without a storage tank. The user can choose various options (e.g., type of water heater alternative to the heat pump water heater, source of electricity, lifecycle methane emission rate, etc.) to construct a scenario. If desired, the user can also build his or her own scenarios by directly entering the CH4 and CO2 emission factors for the reference and alternative technologies, as well as all other parameters given on the left. Clicking on the "Calculate" button calculates the values of technology warming potential (TWP) for the selected scenario and plots them in the graph on the right. TWPs greater than one indicate that the cumulative radiative forcing from choosing the alternative technology (e.g., heating water with a natural gas water heater) at year t is higher than the reference technology (heating water with a heat pump water heater). See Hong and Howarth (2016) for a detailed description of scenarios, equations and parameter estimation.