Publication date: May 24, 2025
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

Stricter Requirements for GX-Oriented and Urban ZEH Homes
The new definition follows the framework of GX-Oriented Housing and requires:
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Insulation performance of Grade 6 or higher
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At least a 35% reduction in primary energy consumption through energy efficiency
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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.

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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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