Annual Survey of Indoor Thermal Environment and Electricity Consumption in Highly Insulated Detached Houses

ABSTRACT

Field evidence on indoor thermal conditions and electricity use in highly insulated detached houses across climates remains limited. Year‐long, cross‐regional monitoring data from all‐electric, highly insulated detached houses in Japan were analyzed using home energy management system records. Indoor air temperature and relative humidity were monitored in living rooms, bedrooms, and dressing rooms, alongside end‐use electricity consumption and photovoltaic generation where installed. Winter indoor conditions were generally warmer and less variable than those previously reported for conventional housing, which may have implications for reduced cold exposure. Summer indoor temperatures were generally moderate, although humidity often approached or exceeded commonly recommended ranges, demonstrating the importance of moisture management in high‐performance housing. Total energy consumption was lower than national residential energy statistics, and an annual net‐zero electricity balance was achieved in a subset of photovoltaic‐equipped houses when assessed using annual generation versus annual use. The dataset provides year‐long reference distributions of indoor conditions and electricity use across multiple Japanese climate areas. Key limitations include uneven regional coverage, non‐standardized sensor placement, and limited information on occupant behavior and system operation. These constraints should be addressed through expanded sampling and complementary surveys.