Resilience of a Net-zero Energy House to Winter Power Outages: Experimental Assessment of Energy Self-sufficiency and Thermal Comfort

• Experimental assessment of a net-zero energy house during a 72 h winter power outage. • Six operation cases analyzed for AC, appliances, and HPWH scheduling under outage conditions. • Minimum power schedule maintained essential loads and thermal comfort with a 5.6 kWh battery. • HPWH operation timing strongly influenced battery depletion and outage risk. • Results inform ZEH design and operational strategies for residential energy resilience. In recent years, climate change has contributed to more frequent and severe natural disasters. These events have, in turn, caused an increase in the number of power outages. Ensuring stable energy supply and maintaining a comfortable indoor environment in residential buildings, including highly insulated detached houses and other eco-friendly homes, have become critical challenges. This study models the electricity consumption patterns of a four-person household and evaluates the energy self-sufficiency and indoor thermal comfort of a super-insulated detached house equipped with photovoltaic (PV) and storage battery (BT) systems during winter power outage conditions. Experiments were conducted under various weather conditions, including clear and cloudy days. The experimental dwelling, situated in Shizuoka, Japan, consists of a steel frame structure with a total floor space of 110.94 m². The thermal properties of the house are defined by an overall heat transmission coefficient (Ua) of 0.48 W/m²·K. The house is fitted with a 5.1 kW PV system and a 5.6 kWh BT, with a maximum supply capacity of 2.0 kVA. Results demonstrate that during winter power outages, a minimum power schedule can maintain essential daily activities and a comfortable thermal environment. Furthermore, by appropriately adjusting the operation timing of air conditioning and heat pump water heaters (HPWH), as well as high-load appliances according to PV generation and BT charge status, the risk of power outage can be minimized and surplus PV power efficiently utilized.