Act Partially Amending the Act on Improvement of Energy Consumption Performance of Buildings

The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) states that the building sector accounts for about 40% of Japan's greenhouse gas emissions. To work towards carbon neutrality by 2050, the amendment creates a system for assessing the carbon emitted over a building's whole life cycle, from the manufacture of materials to demolition, and takes measures to keep pace with energy-saving technology in view of future tightening of energy efficiency standards.

Building owners, architects, construction companies and manufacturers of building materials are given duties to make efforts (non-binding 'duties to endeavour') towards reducing life-cycle carbon, and the government will issue a guideline on life-cycle carbon assessment. For buildings of specified uses above a certain size, the building owner must notify the results of the assessment to the Minister 14 days before construction starts; the uses and size are to be set by Cabinet Order. Manufacturers that calculate the carbon emission factor of materials under the national rules may indicate this on the materials.

The amendment also lets the Minister certify buildings using special structures or equipment as equivalent to the higher 'inducement' energy standard, so that they can use the relief available to certified buildings, including floor-area-ratio relief; requires the largest housing suppliers, designated as 'upper housing top runners', to prepare medium- to long-term plans and report on them every year, with ministerial recommendations where efforts are clearly insufficient; creates third-party certification and labelling of buildings' environmental performance; and renames the Act (in Japanese, 建築物のエネルギー消費性能の向上及び脱炭素化の促進に関する法律; roughly, the Act on Improving the Energy Performance of Buildings and Promoting Decarbonisation, an unofficial translation).

Sources: [1] [3]

The Cabinet decided on the bill on 27 March 2026 and submitted it to the Diet the same day. It was examined by the Committee on Land, Infrastructure and Transport of each House, passed by the House of Representatives on 4 June 2026 and by the House of Councillors on 24 July 2026, which enacted it. It was promulgated on 31 July 2026 as Act No. 75 of 2026; only preparatory supplementary provisions took effect that day.

A draft amendment of the Act's Enforcement Order, setting the designation thresholds for upper housing top runners, was published for public comment on e-Gov from 7 August to 6 September 2026. On 11 September 2026 the Cabinet adopted two Cabinet Orders: one fixing 1 April 2027 as the effective date of the provisions in Article 1(ii) of the supplementary provisions, which cover the upper housing top-runner scheme and the ministerial certification of leading energy-saving technology, and Cabinet Order No. 292 of 2026 amending the Enforcement Order. Both were promulgated on 16 September 2026.

Under the amended Act (Articles 22-2 and 25-2), the Minister is to designate as an upper housing top runner a supplier whose number of houses of the relevant type built in the previous fiscal year is at or above the threshold set by Cabinet Order, so a supplier exactly at the threshold is included; a supplier at or above the threshold that has not been designated must notify the Minister of that number. Cabinet Order No. 292 of 2026 sets the thresholds at 2,000 units for standardised detached houses built for sale (分譲型一戸建て規格住宅), 2,000 units for standardised condominiums and other multi-unit housing built for sale (分譲型規格共同住宅等), 2,000 units for standardised detached houses built under construction contracts (請負型一戸建て規格住宅), and 15,000 units for standardised multi-unit housing built under construction contracts (請負型規格共同住宅等, which MLIT describes as rental apartments).

1. 2026-03-27 — Cabinet decision and submission to the Diet [1] [2]
2. 2026-06-04 — Passed by the House of Representatives [2]
3. 2026-07-24 — Passed by the House of Councillors; enacted [2]
4. 2026-07-31 — Preparatory supplementary provisions take effect [4]
5. 2026-07-31 — Promulgated as Act No. 75 of 2026 [2] [4]
6. 2026-09-16 — Effective-date Cabinet Order and Cabinet Order No. 292 promulgated (Cabinet decision 11 September) [5]
7. 2027-04-01 — Upper housing top-runner scheme and ministerial certification take effect [4] [5] [6]

The timeline of related official records below lists the records this dashboard has matched.

Sources: [2] [4] [5] [6]

Confirmed next steps

• 2027-04-01 — The upper housing top-runner scheme, with the thresholds set by Cabinet Order No. 292, and the ministerial certification of leading energy-saving technology take effect. [4] [5] [6]
• Before the main provisions take effect, the government may already prepare the life-cycle carbon assessment guideline and accept registrations of certification bodies, as the supplementary provisions allow. [4]

Expected procedural steps

The usual procedure for this kind of instrument; not a forecast for this reform.

• A Cabinet Order fixing the date of the main provisions, and Cabinet Orders and ministerial ordinances setting the building uses and sizes subject to mandatory life-cycle carbon notification, would normally be published in draft for public comment before adoption.

Outstanding uncertainties

• The date on which the main provisions, including mandatory life-cycle carbon notification and third-party certification, take effect had not been set when this explainer was verified; the Act requires it to be no later than two years after promulgation (July 2028).
• The building uses and size thresholds for mandatory notification, and the content of the national life-cycle carbon assessment guideline, had not been published when this explainer was verified.

From 1 April 2027, a housing supplier whose number of houses of a given type built in the previous fiscal year meets or exceeds the threshold in Cabinet Order No. 292 (2,000 or 15,000 units, depending on the type) is to be designated as an upper housing top runner and must then prepare medium- to long-term plans and report on them every year; a supplier that meets or exceeds the threshold but has not been designated must notify the Minister of its numbers. Developers using special structures or equipment may seek ministerial certification to access the relief available to certified energy-efficient buildings.

Developers and owners planning larger buildings of the specified uses should expect to carry out a life-cycle carbon assessment and notify its results before construction once the main provisions apply, subject to the uses and sizes still to be set. Designers, contractors and building material manufacturers have new duties to endeavour, and material manufacturers may be asked for emission-factor data calculated under the national rules.

Points to check

• For housing suppliers, count the standardised houses of each type built in the previous fiscal year and compare them with the thresholds (2,000 or 15,000 units; reaching the threshold exactly is enough), ahead of 1 April 2027.
• Identify building projects whose construction would start after the main provisions take effect and could fall within the notification requirement.
• For material manufacturers, review whether product carbon data can be calculated under the forthcoming national rules.
• Track the life-cycle carbon assessment guideline and the Cabinet Orders on covered uses, sizes and the main effective date.

Sources: [1] [3] [4] [5] [6]