Ecodesign requirements for power transformers

Background what is the European Ecodesign Directive 2009/125/EC?

Transformer Design Became Greener from July 2015.

The European Commission Ecodesign Directive (548/2014 & 2009/125/EG) for the implementation of improved energy efficient power transformers came into force in July 2015. As part of continued efforts to reduce the amount of energy wasted in transmission and distribution, the new regulations mandate the use of more efficient low loss transformers.

The Ecodesign of Energy Related Products Directive (ErP) is a European framework that was put in place to help the European Union (EU) achieve its 2020 target to:

• Deliver 20% energy efficiency improvement by 2020
• Lower carbon (CO₂) emission by 20% by 2020
• Increase the share of renewables by 20% by 2020

The current Ecodesign Directive has evolved from an older version which dealt with energy using products (EuP) and was extended to include energy-related products (ErP) in 2009.

The Ecodesign Directive defines minimum requirements for energy related products and has been transposed into UK law (regardless of the connotations of BREXIT) under the Energy Related Products Regulations 2010 SI 2010 No. 2617.

The particular function of the Ecodesign Directive is to improve design on a product specific level. Eliminating the worst performing products from the market and shifting the economy towards solutions with the least life-cycle costs (i.e. total cost of product ownership throughout its lifespan).

Many types of energy-related products are regulated to ensure they meet specific measures relating to their energy usage. This reduces their environmental impact, improves their energy efficiency, and cuts greenhouse gas emissions.


All products in scope must:

In Great Britain and Northern Ireland, the Ecodesign for Energy-Related Products Regulations 2010 (as amended) are the underpinning legislation.

Tier 1 ecodesign requirements have been in place since 1 October 2019 for small, medium and large power transformers in the UK.

Tier 2 requirements regarding these small, medium and large power transformers came into force in the UK from 1 July 2021. The Tier 2 requirements have higher minimum energy performance standards (MEPS) than the former Tier 1 requirements.

All new power transformer installations must be compliant with the minimum requirements set out in Tier 2 from 1 July 2021. However if costs are found to be disproportionate for stakeholders, a Tier 1 (or lower) transformer can be installed.

We have devised a methodology to determine when regulatory relief would apply to installations of Tier 2 transformers when installation costs are found to be disproportionate.


The tool

The purpose of the tool is to help implement the disproportionate costs provision of the Ecodesign regulation. According to the regulation, “installation costs are disproportionate if the costs of the replacement of the complete substation housing the transformer and/or the acquisition or rental of additional floor space are higher than the net present value of the additional avoided electricity losses (tariffs, taxes and levies excluded) of Tier 2 compliant replacement transformer over its normally expected service life. The net present value shall be calculated based on capitalised loss values using widely accepted social discount rates”.

To determine whether any additional expenditure is justifiable, the tool compares:

The Ecodesign regulation also places the requirement to notify the market surveillance authority of regulatory relief by the manufacturer, importer, or authorised representative of the transformer by:

Follow the process here to use the tool to:

Extent of obligation

The manufacturer, authorised representative or importer that first places a regulated product on the Great Britain or Northern Ireland market, or puts it into service, is responsible for compliance of power transformers in Great Britain and Northern Ireland.


How to comply – applying for a regulatory relief

How to use the tool

Before starting this process please note:

The process

  1. Open the regulatory relief tool.
  2. Complete the ‘general info-scenarios tab’. If the installation aligns with any of the cabin-model scenarios please select the option and provide further details in the ‘additional information on chosen scenario’.
  3. If it does align with any of the scenarios in the tool, regulatory relief is applicable. Save the spreadsheet for your own records and follow the next steps in the process outlined in Submission of notification to OPSS.
  4. If the model does not align with any of the cabin-model scenarios, go to the ‘Losses derogation input’ tab to calculate whether regulatory relief is applicable. Instructions are available in the ‘Derogation calculation guidance’ tab.
  5. Once you have determined whether you are eligible for a regulatory relief (either via the cabin-model scenarios or losses derogation input calculation), save the spreadsheet for your own records and follow the next steps in the process outlined in Submission of notification to OPSS.

Submission of notification to OPSS

Only submit a notification of regulatory relief if you are a:

Begin your enquiry here: OPSS enquiry service

From the dropdowns, select:

In the enquiry box, submit the initial text ‘Notification power transformer’ followed by any details of the notification you wish to submit. Please only include:

Please keep relevant records for 10 years as OPSS may seek to retrospectively audit notifications.

Regulatory relief tool methodology

The tool calculates the net present value (NPV) of an investment, taking into consideration the expenses and losses savings associated with that investment. This tool assesses reinforcement options, and within that assessment, the model quantifies societal benefits (including losses). For the purposes of the disproportionate costs calculation, losses benefits (£) are calculated based on the reduced losses achieved by installing a more efficient Tier 2 transformer using the maximum permissible load and no-load losses allowed for each transformer Tier (that is losses benefit = Tier 1 losses – Tier 2 losses). These are then converted to £ using a set of fixed data (provided by Ofgem) such as the price of electricity (average wholesale price) and a greenhouse gas (GHG) conversion factor.

The regulatory relief tool itself has several additional tabs, the majority of which are hidden as they are not in use. The following tabs were added to the tool:

Disproportionate cost modelling tool input fields

Field NameDescription
Weighted Average Cost of Capital (WACC)Used to convert capital costs into annual costs using (DNO specific)
Capitalisation ratePercentage of expense that is capitalised (DNO specific)
Load growth factorA factor by which load increases annually (location specific)
Load loss factor (LLF)A factor applied to the site of a substation to take account of the cyclic nature of the load (location and substation specific). It is used to calculate copper/variable losses (location specific)
Site demandDemand expected on transformer
Reference yearReference Calendar Year and Year of Installation inform the discounting calculations. If 2018/19 is inputted the NPVs the tool calculates will be discounted to 2019. It is advisable to choose the same discounting year as the price base year. Note that the price base for this tool should be 2018/19 as in the Guidance tab – the user should enter real 2018/19 costs or use the CPIH indices in the Fixed Inputs tab to convert all costs/benefits in 2018/19 prices (this is built into the tool)
Year of installationThe year the transformer is expected to be installed.
Transformer ratingSize of transformer in MVA
Copper lossesAlso known as variable losses which occur due to the resistance of the transformer windings. These losses are load dependent and as such are calculated using an LLF.
Iron lossesAlso known as fixed losses which occur by the alternating flux in the core of the transformer. These losses do not depend on load.
Building and civils costCost incurred to install a transformer

For any further questions on the methodology of this regulatory relief tool please use the OPSS enquiry service.

The role of the Office for Product Safety and Standards (OPSS)

OPSS is the appointed Market Surveillance Authority for Ecodesign Regulations in Great Britain and Northern Ireland.

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