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Japan reports revision of energy efficiency standards for gas water heaters

Time：

2026-01-19

On December 23, 2025, Japan issued a notification through the WTO to revise new energy efficiency standards for gas water heaters. This revision specifies specific requirements in terms of the scope of application of the standard, energy efficiency and measurement methods, categories and standard values, compliance determination methods, label information, etc.

On December 23, 2025, Japan issued Notice G/TBT/N/JPN/892 through the WTO, revising new energy efficiency standards for gas water heaters. This revision specifies specific requirements in terms of the scope of application of the standard, energy efficiency and measurement methods, categories and standard values, compliance determination methods, label information, etc.

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Main content

01. Scope of application

Gas water heater.

The following gas water heaters are not applicable to this standard: storage water heaters; Products that do not comply with JIS S 2109 (2019 edition) or JIS S 2112 (2019 edition); Commercial manufacturing products; Products that use gases other than urban gas group 13A as fuel; Natural ventilation gas instant water heater, with non open intake and exhaust systems; Gas bath heaters belonging to any of the following categories: products without hot water supply function, natural ventilation products, natural circulation system products, and products designed for indoor installation; A product specifically designed for heating.

02. Energy Efficiency and Measurement Methods

Gas hot water equipment without heating function: Energy efficiency is evaluated based on mode thermal efficiency (%), and the measurement method follows the "Method for Measuring Mode Efficiency of Domestic Gas and Oil Hot Water Equipment" (JIS S 2075:2011).

Gas hot water equipment with heating function: The energy efficiency is calculated by weighted average of the rated thermal efficiency (%) of the heating part and the rated thermal efficiency (%) of the hot water supply part in a ratio of 1:3; The measurement method for the rated thermal efficiency of the heating section follows the "Measurement Method for Household Gas Hot Water Sources" (JIS S 2112:2019), and the measurement method for the rated thermal efficiency of the hot water supply section follows the "Measurement Method for Household Gas Hot Water Equipment" (JIS S 2109:2019).

03. Category and target standard values

Table 1: Target standard values for gas water heaters

Category	Purpose	Ventilation type	Target standard value
Ⅰ	Gas instant water heater	natural ventilation	77.6%
Ⅱ	Gas instant water heater	Forced ventilation	85.6%×αⅡ
Ⅲ	Gas bath heater	-	89.8%×αⅢ
Ⅳ	Gas heating equipment	-	91.3%

Table 2: Structural coefficients (α II and α III)

Coefficient	Structural type	Structural coefficient values
αⅡ	wall-penetrating	0.9981
	embedded	0.9928
	Forced ventilation type	0.9814
	Traditional forced exhaust type	0.9802
	Traditional integrated range hood type	0.8307
	other	1.0000
αⅢ	wall-penetrating	0.9921
	Traditional Embedded Systems	0.9189
	other	1.0000

04. Standard determination method

Manufacturers need to ensure that in each fiscal year after the target year, based on the shipment volume of each category of products, the weighted harmonic average of energy efficiency is not lower than the weighted harmonic average of the target standard energy efficiency.

05. Label information requirements

Manufacturers need to label performance related information on product catalogs and equipment bodies, and ensure that the information is clear and visible.

Compliance recommendations

The revision of water heater related standards announced by Japan this time has made new regulations on the energy consumption standards of some categories of water heaters. Export enterprises should closely monitor the dynamics of this standard, actively communicate with local customers, understand the latest requirements of the relevant standards, ensure that the energy consumption of water heater related products meets the requirements of the exporting country, and pay attention to the effective date of the relevant standards, optimize the product industry layout, and avoid compliance delays affecting exports.

As a professional third-party testing and certification service organization, Jiayu Testing has qualifications such as CMA, CNAS, CBTL, and has been recognized by multiple authoritative certification agencies at home and abroad. It is equipped with advanced instruments and equipment, has a skilled professional technical team, rich industry service experience, and strong testing technology capabilities. It is proficient in various regulatory standards and specializes in providing multi country energy efficiency certification services for electronic and electrical products to ensure that they meet relevant regulatory requirements. If your product requires safety and energy efficiency certification, please feel free to contact us at 400-9269-886!