EQUIPMENT CONSTITUTION AND OCCUPANT BEHAVIOR IN A NET ZERO ENERGY HOUSE CONSIDERING STAYING AT HOME DURING POWER OUTAGES

The goal of this study is to propose combinations of equipment, including photovoltaic (PV) power generation and storage battery (BT) charging, in a net zero energy house (ZEH) that considers sheltering at home during power outages. To validate the resilience performance of houses in various conditions compared to a ZEH house, the self-sufficient rate during power outages was calculated based on PV capacity, BT capacity, and insulation performance. Assuming that the power supply is limited, such as in the case of small BT capacity and bad weather, an occupant behavior was proposed to make efficient use of the limited power supply and evaluated based on the self-sufficient rate and thermal environment. Moreover, the economic efficiency of the ZEH was calculated to prove the feasibility of the study. The following observations are reported in this article: 1) The thermal insulation was effective in reducing the electricity consumption for heating and cooling, and the reduction was particularly pronounced in the winter. The impact of increased PV capacity on the increase in the self-sufficient rate is small compared to the changes in thermal insulation and BT capacity. In addition, with a UAvalue which is thermal transmittance of 0.46 W/(m2・K), the installation of BT results in an 80% self-sufficient rate. Notably, the self-sufficient rate increases proportional to the increase in BT capacity. Under conditions of BT capacity of 6.2 kWh or more, 100% self-sufficient rate was achieved. Furthermore, by setting the BT residual rate for emergency, the self-sufficient rate is further increased, and the resilience of the occupants in the ZEH is increased in cases of unexpected power outages. 2) Even in conditions where the BT capacity is less than 5.6 kWh, a BT is not installed, or there is low solar radiation, occupant behavior, such as reducing the air conditioning range and limiting the home appliances’ time of use, can help maintain thermal comfort without compromising health. When a BT is not installed, the starting power of the air conditioner in winter exceeds the maximum power output of the self-support circuit, making it difficult to use the air conditioner. However, it has been shown that the air conditioner can be used both in the summer and winter by installing a BT. Therefore, in a house with a UA value of 0.46 W/(m2・K), it is noted that the installation of a BT can be expected to serve to further prepare for power outages, even when the occupant beh