CO2 emissions in electrified detached houses with photovoltaic generators: An hourly emission-profile approach with demand-side management and battery integration

Residential energy systems are moving toward carbon neutrality as households electrify their energy demand and install photovoltaic (PV) generators. These shifts alter the household demand profiles and temporal generation-side variations, causing significant shifts in carbon dioxide (CO2) emission patterns. This trend highlights the need for hourly CO2 emission factors to quantitatively capture emission dynamics and, in turn, resolve demand–supply imbalances and reduce overall CO2 emissions. Therefore, this study proposes an integrated control strategy of appliances and batteries (BTs) in electrified houses with PV generators. The control method minimizes the demand–supply imbalance by maximizing household energy self-sufficiency using an exhaustive search algorithm. The controller schedules heat pump, water heater, air conditioner, and BT operations based on the PV availability. We conducted a case study using Japanese household data and different PV-BT capacities to evaluate the control performance. The results indicate that 78–82% of the daily household CO2 emissions occur between 4p.m. and 8 a.m., when the hourly CO2 emission factors are higher than those during daylight. Under the same PV-BT capacity, for Tokyo, the controlled system reduced the monthly CO2 emissions by 9–23% and decreased the annual household costs by 4–10% under a CO2 tax scenario when compared with the uncontrolled method. These findings indicate that coordinating the appliance and BT operations with PV generation can effectively reduce residential CO2 emissions and support demand-side pathways toward energy self-sufficient carbon–neutral homes.