Energy consumption in Japan’s building sector peaked in 2005 and decreased by 16% between 2005 and 2019. Since 2005, electricity use in the sector has largely flattened out and oil use has decreased by around 42%, the main driver of the overall decrease in consumption and declining emissions.
Direct CO₂ emissions of the building sector have been declining since 2002 reaching around 109 MtCO₂/yr in 2030. The largest decrease in direct CO₂ emissions occurred between 2002 and 2010 (2002 also being the year when overall emissions from the sector peaked). This period of emissions reduction corresponds with the roll out of Japan’s Top Runner Programme, which began in 1998 and is ongoing. The programme sets energy efficiency standards for home appliances which are reviewed every 2 to 3 years.
As part of its long-term strategy, the Japanese government aims to achieve integrated use of demand and supply in rooftop PV through “sector coupling” of electricity, heat, and mobility. To this end, the government is promoting and/or investing in hydrogen infrastructure, electric vehicle charging stations, information and communication technology for demand side management. Sector coupling is seen as a way to improve efficiency and allow for greater utilisation of renewable electricity.
The 1.5°C compatible pathways have direct emissions form the building sector falling by 34-48% from 2019 levels by 2030 and reaching net zero between 2040-2052. For most pathways, this drop in emissions is achieved largely through fuel switching, mostly through electrification but also through the use of hydrogen and liquid biofuels. Electricity’s share of final energy in the sector increases from 53% in 2019 to 66-69% by 2030 and 88-89% by 2050, and this is would be concurrent with the rapid increase of renewables in the power sector described above. Total energy demand remains around current levels or decreases slightly out to 2050 and beyond. Where a significantly lower demand is projected, the drop in consumption mostly affects oil and natural gas use. The overarching message is that renewable power will play a primary role in decarbonising the building sector