Japan's Agency for Natural Resources and Energy has opened a public comment period on draft rules that would make household water-heater manufacturers and importers set their own fossil-energy target, publish it and then meet it. The comment window runs from October 22 to November 20, 2026, and the drafts are planned to take effect on April 1, 2027.
One standard instead of two
The draft notice replaces two separate sets of criteria, the 2004 notice for gas water heaters and the 2013 notice for electric ones, with a single notice covering both. It also carries forward efficiency tables for gas-fired and heat-pump water heaters. A companion draft ministerial ordinance amends the exemption list in the enforcement regulations. Like the notice, it would take effect on the date the amending cabinet order does, April 1, 2027.
The new target covers gas combustion water heaters, heat-pump units, electric-heater units, hybrids and home fuel cells. Natural-draft gas instantaneous water heaters are carved out. The working group summary also exempts commercial-use units and some other categories.
How the mechanism works
For the year beginning April 2034 and every year after, each maker's shipment-weighted fossil-energy consumption for household units sold in Japan must not exceed a value the maker sets itself. Makers first write a shipment policy for three kinds of setting. In homes judged well suited to high-efficiency units, they are to ship high-efficiency heaters. In other homes with no constraint on condensing gas units, they are to ship units at least as efficient as a latent-heat-recovery gas model. High-efficiency means heat-pump, home fuel-cell and hybrid units.
The consumption figure is calculated from annual hot-water heat load, gas and electricity use, and fossil-energy coefficients. Space-heating energy is excluded. Makers must publish their policies and targets by March 31, 2028, and publish again if they revise them.
The 5,605 MJ guide
The state's quantitative guide is 5,605 MJ of fossil energy per unit, per person. It is a reference for makers' own target-setting, not a limit on individual products or a sales threshold. The working group derived it from an assumed shipment mix by water-heater type in the target year.
| Water-heater type | Assumed target-year share (%) | 2023 fiscal-year actual (%) |
|---|---|---|
| High-efficiency (heat pump, home fuel cell, hybrid) | 39.3 | 22 |
| Latent-heat-recovery gas | 42.5 | 29 |
| Other | 18.1 | 49 |
Enforcement and what is still open
According to the working group summary, the state will check whether target-year results meet the maker's own value. It may issue a recommendation to improve energy performance if a maker's policy and target are judged not to reflect the criteria, or if the target-year result falls short, and the state considers substantial improvement necessary. The summary also says makers should consider raising targets if the market allows.
These are drafts, not adopted rules, and the notice's number and date are blank. METI says it will treat comments as reference for the final decision and will not reply to them individually. Comments go in Japanese through e-Gov, by post or by email.