METI to Tighten Green Housing Standards

METI announced its intention to revise the definition of ZEH (net Zero Energy Houses) at an expert meeting. The revised standards will align with the “GX-Oriented Housing” concept introduced by the government last year, requiring the same level of insulation performance and energy-saving efficiency in reducing primary energy consumption. For detached houses, the new criteria will also require the installation of a small-sized battery energy storage system (BESS) and an advanced energy management system.

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Certification Timeline and Current Requirements

Certification under the new ZEH standards will begin in FY2027. New certifications under the current standards will continue until the end of FY2027, and renovations to homes built up to FY2027 can still be certified under the existing definition. Under the current ZEH definition, a home must:

Introduce renewable energy systems to reduce annual primary energy consumption to net-zero or below
Achieve at least a 20% reduction in primary energy consumption through energy efficiency
Meet or exceed Insulation Grade 5

METI to Tighten Green Housing Standards. ZEH (Net Zero Energy House). — Image Source: Yamato JK, “ZEH – Zero Energy House,” Yamato JK, https://www.yamatojk.co.jp/en/zeh/

Stricter Requirements for GX-Oriented and Urban ZEH Homes

The new definition follows the framework of GX-Oriented Housing and requires:

Insulation performance of Grade 6 or higher
At least a 35% reduction in primary energy consumption through energy efficiency
A total reduction (including renewable energy) of 115% in primary energy consumption

If the home has solar panels installed, a residential BESS with a usable capacity of at least 5 kWh must be installed. Installation of electric vehicle (EV) chargers and bi-directional chargers will also be recommended.

METI to Tighten Green Housing Standards. Current ZEH vs New ZEH Standards — Current ZEH vs New ZEH Standards

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Updated Rules for High-Rise ZEH Oriented Homes

Additionally, the criteria for “ZEH Oriented” houses, which are not required to include renewable energy systems, located in snowy regions or urban areas with limited space, will also be revised. The updated criteria will be applied to high apartment buildings of six floors or more.

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