2025/26 Annual Research Programme: Updated criteria now live

18 sub-technologies reviewed, with criteria updated across 11

To ensure the ETL continues to identify the most energy efficient products available, we regularly review our technology categories and update criteria to reflect changes in market expectations, testing standards and product performance. 

Following the 2024/25 Annual Research Programme, which resulted in updates to 12 criteria, we are pleased to announce the outcomes of the 2025/26 Annual Research Programme. We have reviewed 18 sub-technologies to assess whether their criteria remain relevant and continue to identify the most energy efficient products in their class.  

The programme included full technical reviews of ten sub-technologies and targeted reviews of eight others, focusing on specific areas of clarification or refinement. The reviews considered measurement standards, testing routes, performance thresholds and eligibility requirements. Following technical research, evidence gathering and consultation, criteria have been updated across 11 sub-technologies. 

Where currently listed products are affected, we have contacted manufacturers directly. Existing listings are not automatically invalidated when criteria change. However, we may ask manufacturers to provide updated information or evidence so that affected products can be reassessed against the revised criteria. 

While all selected sub-technologies were assessed as part of the process, updates have been made only where the evidence identified a clear case for revising the criteria.  

Criteria have been updated across sub-technologies in the following categories: 

• Energy Monitoring 

• Boiler Equipment 

• Motors, Drives and Fans 

• Compressed Air Equipment 

• Refrigeration Equipment 

• Energy storage 

• Showers 

The changes affecting each sub-technology are summarised below. 

Energy Monitoring

Automatic Monitoring and Targeting (aM&T) Sub-Metering Systems

Measurement standards have been updated for electricity, gas and heat meters: 

Electricity meters

• BS EN 50470-3:2022 “Electricity metering equipment - Particular requirements. Static meters for AC active energy (class indexes A, B and C)”.  

The remaining requirements for electricity meters are unchanged. 

Gas meters

• BS EN 12261:2024 “Gas Meters - Turbine gas meters”.   

Products listed on the ETL before 1 January 2026 and tested in accordance with BS EN 12261:2018 will continue to be accepted. 

Heat meters

• BS EN 1434-1:2022 “Heat meters. General requirements”.  

• BS EN 1434-4:2022 “Heat meters. Pattern approval tests”.  

• BS EN 1434-5:2022 “Heat meters. Initial verification tests”.  

Products listed on the ETL before 1 January 2026 and tested in accordance with BS EN 1434-1:2018, BS EN 1434-4:2018 and BS EN 1434-5:2019 will continue to be accepted. 

Boiler Equipment

Several updates have been made to the criteria for Biomass Boilers, Hot Water Boilers and Gas-fired Condensing Water Heaters. These affect measurement standards as well as eligibility, performance and testing requirements. 

Biomass Boilers

One performance requirement has been updated: 

• Eligible biomass boilers with a rated heat output of 500 kW or less must now meet or exceed a Seasonal Space Heating Energy Efficiency (ηs) value of 81%, as defined in Ecodesign Commission Regulation (EU) 2015/1189. 

Measurement standards and related test requirements have also been updated: 

• Products with a rated heat output of 500 kW or less must now be tested in accordance with BS EN 303-5:2021+A1:2022 “Heating boilers for solid fuels, hand and automatically fired,  nominal heat output of up to 500 kW. Terminology, requirements, testing and marking”. 

• For products with a rated heat output of 500 kW or more, BS EN 303-5:2021+A1:2022 has been added as an alternative testing standard alongside the existing standards recognised by the ETL. 

• Performance testing must be carried out using a biomass test fuel that complies with Table 9 of BS EN 303-5:2021+A1:2022 and reflects the product’s intended use. 

• Emissions testing requirements have been updated to require measurement of particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO) and organic gaseous compounds (OGCs) in accordance with the relevant provisions of BS EN 303-5:2021+A1:2022. 

Products listed on the ETL before 1 January 2026 and tested in accordance with EN 303-5:2012 will continue to be accepted. 

Hot Water Boilers

Test standards have been updated for product categories 3 and 4 (Condensing hot water boilers >70kW) and Condensing hot water boilers ≤70kW ): 

• BS EN 15502-1:2021+A1:2023 “Gas-fired heating boilers. Part 1: General requirements and tests”. 

• BS EN 15502-2-1:2022+A1:2023 “Gas-fired central heating boilers. Specific standard for type C appliances and type B2, B3 and B5 appliances of a nominal heat input not exceeding 1000 kW”.  

• BS EN 15502-1:2021+A1:2023 has been introduced as an accepted testing standard, replacing BS EN 15502-1:2012+A1:2015 and a number of legacy standards previously recognised by the ETL. 

To support the transition to the updated standard, performance data obtained in accordance with BS EN 15502-1:2012+A1:2015 will continue to be accepted as an alternative to BS EN 15502-1:2021+A1:2023 until further notice. 

Gas-fired Condensing Water Heaters

Eligibility requirements have been updated to include compliance with: 

• The Water Supply (Water Fittings) (Scotland) Byelaws 2014.  

• The Water Supply (Water Fittings) Regulations (Northern Ireland) 2009. 

Performance requirements regarding the minimum gross water heating energy efficiency (ηwh) for gas-fired condensing water heaters with a rated heat output of 400 kW or less have been updated: 

• A new threshold of ≥77.0% has been introduced for declared load profile M. 

• A new threshold of ≥85.0% has been introduced for declared load profile L. 

• A threshold of ≥85.0% now applies to declared load profile XL, increased from ≥80.0%. 

Measurement standards for products with a rated heat output of 400 kW or less have also been updated: 

• Gross water heating energy efficiency must now be determined according to BS EN 13203-2:2022 “Gas-fired domestic appliances producing hot water - Assessment of energy consumption”.  

For products with a rated heat output above 400 kW, three standards have been updated within category 3 (Non-storage, circulator (or multi-pass) type, gas-fired condensing water heaters) and two standards have been updated in category 2 (Non-storage, instantaneous (or continuous flow) type, gas-fired condensing water heaters): 

• BS EN 15502-1:2021+A1:2023 “Gas-fired heating boilers. General requirements and tests”. (category 3) 

• BS EN 15502-2-1:2022+A1:2023 “Gas-fired central heating boilers. Specific standard for type C appliances and type B2, B3 and B5 appliances of a nominal heat input not exceeding 1 000 kW”. (category 3) 

• BS EN 26:2023 “Gas-fired instantaneous water heaters for the production of domestic hot water”.  (category 2 and category 3) 

• BS EN 26:2023 “Gas-fired instantaneous water heaters for the production of domestic hot water”. (category 2)  

Performance data obtained in accordance with the previous standards listed in the criteria will continue to be accepted until further notice. 

Motors, Drives and Fans

Line Operated AC Motors

One eligibility requirement has been updated for both single-phase and three-phase motors: 

• Motors must have dimensions and a power rating that conform with IEC 60072-1:2022 “Rotating electrical machines - Dimensions and output series - Part 1: Frame numbers 56 to 400 and flange numbers 55 to 1080”.  

Products listed on the ETL before 1 January 2026 in accordance with IEC 60072-1:1991 02 (sixth edition) will still be accepted. 

Performance threshold tables have also been updated for three-phase line operated AC motors from 0.12 to 1000 kW (Table 1.1), Ex-eb increased safety motors (Table 1.2) and single-phase line operated AC motors (Table 1.3). Please refer to the latest criteria document for full details of the updated thresholds. 

An updated test standard has also been introduced:  

• BS EN IEC 60034-2-1:2024 “Rotating electrical machines – Part 2-1: Standard methods for determining losses and efficiency from tests (excluding machines for traction vehicles)”. 

Until further notice, test results obtained in accordance with  BS EN 60034-2-1:2007 for products listed before September 2020, and BS EN 60034-2-1:2014 for products listed before March 2024, will continue to be accepted. 

Compressed Air Equipment

Refrigerated Air Dryers with Energy Saving Controls

A performance requirement has been updated: 

• The maximum allowable composite SEC has been reduced  to ≤0.38 kW/m³/min. 

Refrigeration Equipment

Updates have been made across Refrigerated Display Cabinets, Retrofit Measures for Open Fronted Refrigerated Display Cabinets and Air-Cooled Condensing Units. 

Refrigerated Display Cabinets

Testing standards have been updated:  

• All cabinets shall be tested in a test room conforming to BS EN ISO 23953-2:2023 “Refrigerated display cabinets - Part 2: Classification, requirements and test conditions”.  

• For commercial beverage coolers, the testing standard BS EN ISO 22044:2022 remains unchanged. 

• For listed products containing glass, the Total Display Area (TDA) must be recalculated in accordance with BS EN ISO 23953-2:2023 or BS EN ISO 23953-2:2015.  

• For water loop cabinets, the inlet chilled water flow temperature  is now 30°C.  

Products tested in accordance with the procedures and standard rating conditions laid down in BS EN ISO 23953-2:2015 will be accepted as an alternative until further notice.  

Products listed on the ETL before 1 January 2026 and tested in accordance with BS EN ISO 23953-2:2005 or BS EN ISO 23953-2:2005+A1:2012 will still be accepted.  

An information requirement has also been added: 

• Suppliers and manufacturers must now report whether the refrigerated display cabinet is open or closed.  

Retrofit Measures for Open Fronted Refrigerated Display Cabinets

The criteria definitions have been updated to clarify the product types covered. The ETL Method for Testing Retrofit Measures for Open Fronted Refrigerated Display Cabinets has also been updated to reference BS EN ISO 23953-2:2023. The ETL test method requires the refrigerated display cabinet used for testing to be listed on the ETL. 

Air-Cooled Condensing Units

The scope of this sub-technology has been expanded to include CO₂ (R744) transcritical systems, where heat rejection occurs through a gas cooler rather than a conventional condenser. As a result, an eligibility requirement regarding the required heat rejection component within the list of mandatory factory-assembled unit components has been updated: 

• Eligible products must incorporate an air-cooled heat rejection device, either a condenser or gas cooler, appropriate to the refrigerant and operating mode. 

The following two standards have been updated: 

• BS EN 13215:2016+A1:2020 “Condensing units for refrigeration. Rating conditions, tolerances and presentation of manufacturer’s performance data”. 

• BS EN 12900:2025 “Refrigerant compressors. Rating conditions, tolerances and presentation of performance data”. 

For product categories where a COP threshold is specified, performance data obtained in accordance with BS EN 13215:2000 will continue to be accepted as an alternative to BS EN 13215:2016+A1:2020 until further notice.  

Products tested in accordance with BS EN 12900:2013 will also be accepted until further notice.  

Energy Storage

Thermal Energy Storage

An eligibility requirement has been updated: 

• The minimum threshold has been updated to 100 kWh.  

This change broadens eligibility to include a wider range of smaller commercial and building-scale thermal energy storage systems. 

An additional testing route has also been introduced, allowing applicants to use the “Design Calculations: Representative Testing” route to demonstrate that products conform with the requirements. Further details on this testing route can be found in the ETL Testing Framework. 

Showers 

Showers 

Performance requirements for electric showers have been updated, introducing additional pathways for products with higher maximum flow rates to qualify: 

• The standard maximum available flow rate remains 4.5 l/min. 

• The maximum permitted flow rate increases to 9 l/min where the product is designed to modulate electric power input and minimise electricity use, while maintaining a stable output temperature when connected to an ETL compliant wastewater heat recovery system. 

• The maximum permitted flow rate increases to 10.6 l/min where the product also includes user behaviour features. 

Find out more 

To learn more about how categories are reviewed, how evidence is assessed and how manufacturers can contribute, read about the role of the ETL Annual Research Programme. 

If you manufacture an energy saving technology that is not currently covered by the ETL, you can put it forward for inclusion through a New Technology Proposal (NTP). Each proposal is assessed for its potential to meet ETL scheme requirements and deliver UK-wide CO₂ savings.  

Read our guidance note to learn more about the process. 

Already have products listed on the ETL?  Learn how to make your listing work harder, promote it more effectively and help customers understand the value of choosing your products. 

For questions about the updated criteria or how they may affect your products, please contact the ETL team at info@etl.energysecurity.gov.uk