The carbon dioxide emitted from our economic activities (mainly the combustion of oil, coal, and gas) is causing global warming, and scientists have pointed out that this poses many irreversible risks. For this reason, at the end of last year, all countries around the world adopted the Paris Agreement, which aims to limit the rise in the global average temperature to within 2°C since the Industrial Revolution and to create a zero-carbon society in the second half of this century. (The temperature has already risen by about 1°C in about 100 years.) The rise in average temperature is determined by the total cumulative amount of carbon dioxide emissions, and it is estimated that the upper limit is 3 trillion tons. Since 2 trillion tons have already been emitted, it is said that humanity has only 1 trillion tons of emission margin left. In recent years, the world has been emitting about 30 billion tons of carbon dioxide annually through economic activities, so if this continues, 30 billion tons x approximately 30 years (2050) ≈ 1 trillion tons, which will reach the upper limit. High insulation and energy conservation measures that are an extension of the past will not be enough, and it is necessary to set discontinuously high targets for zero energy and zero carbon and make every effort to achieve them. It is said that if we pass on these challenges to our children's generation, it will be too late to solve them. In the long term, many countries around the world are aiming for zero-energy buildings, and by 2050, many countries are aiming for carbon neutrality not only for new construction but also for existing buildings as a whole. We must fulfill our responsibility to the future as our generation and be ready to welcome 2050.