City-level energy and CO2 reduction effect by introducing new residential water heaters

Simulation models for a variety of new water heater systems were developed and the models were integrated into a city-level residential energy end-use model for Osaka City. Using the model, the potential of energy conservation and CO2 emission-reduction by introducing new residential water heaters was evaluated at the city-level. Optimal water-heating systems for each household category for primary energy reduction, CO2 emission-reduction, or cost reduction were identified by applying the end-use demand model. The effect of subsidies for installing more efficient systems and the influence of diffusion of these systems on electricity load curves were also discussed.