Reduction potential of operational carbon dioxide emission of Nakanoshima business/cultural area as a model for low-carbon districts in warm climates

This study examines a scenario for realizing large-scale reductions of operational carbon dioxide (CO2) emission in commercial districts in temperate and tropical zones. In warm climates, energy usage for heating is not dominant in a buildingʹs energy usage, and hence, every available emission reduction technology must be fully utilized to achieve a large overall reduction in emissions, as in the scenario examined in this study. The focus is on commercial buildings in Nakanoshima area, a sandbank 3 km long and 50 ha wide, a central business and cultural area in the city of Osaka, Japan. The commercial buildings in Nakanoshima with approximately 1.2 million square meters of total floor area emitted 88 thousand tons of CO2 in 2008. The method used in this paper combines: 1) energy flow analysis, 2) community-scale building performance simulation validated with actual energy consumption and supported by detailed field survey and reference survey, and 3) what-if analysis assuming technological deployment and social change based on a long-term perspective. It enables a comprehensive understanding of how much energy is consumed for what purpose as well as how much energy can be reduced by implementing which technologies and measures. The result showed that approximately 65% emissions of the present operational CO2 emission could be reduced in the coming decades.