In addition to energy-saving of equipment, generating renewable energy through photovoltaic (PV) power generation is also effective for reducing CO₂ emissions during the operation phase of buildings. While PV panels installed on rooftops and other locations are becoming widespread as a form of energy generation technology, there is the issue that the amount of power generated varies greatly depending on the weather, time of day, and sunlight conditions of buildings. In urban areas, the amount of PV that can be installed is limited owing to the size of the roof area, so it is essential to install building-integrated PV (BIPV). In addition to on-site renewable energy, the dynamic emission factor of grid power, which varies depending on the time of day, has been attracting attention in recent years. To make the most of electricity with low emissions, batteries are essential, so it is necessary to comprehensively consider the implementation of PV panels and batteries together. Furthermore, the inequality of sunlight conditions among buildings is a major issue when introducing PV panels. Moreover, the compatibility of power demand characteristics and batteries is a major issue when introducing batteries, so the rational introduction will be possible by linking multiple buildings energetically.　With the above background, in this study we focused on the implementation of energy system design and operation at the neighborhood scale, targeting PV panels and batteries. Current system hinder sharing renewable energy resources and the electricity they generate among multiple buildings, or sharing storage batteries. However, assuming that this is possible, we aimed to demonstrate the CO₂ emission reduction effect of such measures and thereby to contribute to reducing the social cost of PV panels and batteries. First, we addressed the optimal allocation of PV panels on buildings and the methods for introducing and comparing them on an individual or neighborhood-scale basis using a dynamic CO₂ emission factor that changes every hour. As a result of targeting 42 neighborhoods in Tokyo, we obtained an average increase in emission reductions of 8%. Next, we examined the effect of introducing batteries. As a result of applying an optimal charging/discharging algorithm based on the concept of model predictive control to a combination of multiple building uses (business, residential, commercial, accommodation, and medical), the increase in emission reductions reached a maximum of approximately 80%. Next, we examined the case in which both PV panels and batteries were introduced. The introduction of solar panels and batteries in the neighborhood resulted in an increase in emissions reduction of approximately 70% compared to the introduction of each building, and it was confirmed that their introduction at the neighborhood scale was effective. Finally, we calculated the effect of introducing PV panels and batteries in a real neighborhood with real energy and weather data. As a result of using real data rather than hypothetical values for such input data, we confirmed that an 8% reduction in emissions could be achieved. We confirmed that the proposed method is also effective in the operational stage of a real neighborhood. Future issues for the practical application of this method include examining the constraints on PV installation that consider the window area ratio of buildings and a prediction method that considers the variation in the CO₂ emission factor in near future.

This study analyzes the impact of climate change and the improvement of building envelope standards on the heating and cooling load of detached houses in six cities across Japan (Sapporo, Morioka, Akita, Sendai, Tokyo, and Kagoshima). Using weather data spanning approximately 30 years from the 1990s to the 2010s, the study evaluates the effects of both the gradual enhancement of envelope standards and climate change on the heating and cooling load. The results reveal that the cooling load tends to increase due to global warming, and the mitigating effect of improved envelope standards is limited. In contrast, the heating load can be steadily reduced through enhanced envelope performance, with the effect being particularly pronounced in cold regions.