The number of disasters causing power outages has been increasing recently in Japan. The goal of this study is to propose equipment installation before and occupant behavior during the power outage in a net zero energy house (ZEH) by calculating the self-sufficient rate. This rate has been evaluated in terms of photovoltaic system capacity, storage battery capacity, and thermal insulation. Occupant behavior in the case of no storage battery and bad weather has also been proposed. Moreover, the economic efficiency of ZEH was calculated to prove the feasibility of the study.
This study proposes operational strategies for combinations of equipment, including an electric vehicle (EV), in a house using self-consumption.The aim of this is to attain both comfort and efficient energy management under several household and regional conditions, focusing on the frequency of the EV's use as well as the residents' schedules. As operational strategies for self-consumption of surplus power, storage battery (BT) charging, EV charging and daytime operation of heat pump water heater (EC) were assumed. Moreover, the amount of self-consumption, CO2 emissions, and the cost-effectiveness of different equipment combinations were calculated and compared.
Because of the increasing promotion of renewable energy such as photovoltaic (PV) panels in Japanese houses, the voltage increase and frequency adjustment of a city electrical distribution network sys-tem will be of concern. Therefore, self-consuming surplus electricity and leveling the reverse power flow is important in terms of reducing the smart grid network load and reducing the peak load of the smart grid network. The aim of this study was to acquire knowledge regarding methods of self-consuming surplus power as well as leveling the reverse power flow. An equipment operation method, termed “schedule control,” was proposed that changes the operational time of a heat pump water heater and the charging time of a storage battery according to solar radiation prediction. Because PV power fluctuates depending on weather and time zone, this method helps in self-consuming as much PV power generation as possible. By actual measurement and simulation results, it was confirmed that the schedule control of the heat pump water heater and storage battery was useful in self-consuming surplus power and leveling reverse power flow.
The purpose of this study is to investigate the energy consumption, power supply and demand of all-electrified net Zero Energy Houses (ZEHs).Energy measurement data of 67 all-electrified ZEHs was analyzed based on a nationwide survey conducted from 2018 to 2019. The primary energy consumption of all-electrified ZEHs was described in comparison with conventional houses. By analyzing the self-consumption rate, the selfsufficient rate, the amount of sales and purchase power, and the charging and discharging of storage batteries, it was inferred that most of the allelectrified ZEHs today are operated with profit as the objective, obtained by selling more electricity.
Considering the effects of electricity shortages caused by natural disasters in Japan, residential energy efficiency is essential. In addition, excessive housing stocks in Japan have highlighted the importance of expertise in renovation methods for zero-energy houses (ZEHs). Therefore, we designed and built a ZEH as a refurbishment of steel-structure industrialized housing to acquire knowledge on ZEH design and renovation. The renovation uses a highly insulated volume against a low insulation volume, which is assumed to be an existing house. The space between the low-insulation wall facing the outside and the high-insulation wall surrounding the main living space functions as a sunroom and called a loggia. By opening and closing the inside and outside windows according to the season and time of day, the loggia functions as a passive system to reduce the air-conditioning load. In this paper, the outline of the building plan of the experimental house and the evaluation of the thermal environment are presented.
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