Green transformers: a step change in transformer efficiency



Transformers act as the gateway to power for any property large enough to connect directly to the national grid. From 1st July 2015, the latest amendment to the European Commission’s Ecodesign Directive will come into force, and put transformer efficiency directly under the microscope.

Steve Marr, Lead Marketing Manager for Legrand’s Power Distribution business unit, demystifies some of the confusion surrounding the new directive and outlines how it will help bring about a step change in transformer efficiency.

Despite being an essential part of all high voltage electrical power systems, transformers are a key area of concern when it comes to the overall energy efficiency of a power distribution system.

One particular aspect that has drawn much attention is that as many large non-domestic buildings – such as offices, shopping centres, government buildings and schools to name but a few – are only occupied for 50-60 per cent of the week, transformers are often placed on stand-by for long periods of time. As transformers are constantly connected to the grid, it is during this stand-by period that inefficient transformers are susceptible to significant energy wastage (commonly known as ‘no-load losses’).
It is this wastage, combined with ‘load losses’ – the energy lost when the transformer is in use – which is the key focus of the latest EU changes under its new transformer directive.

Directive overview

In short, the new transformers  legislation is intended to eradicate transformers with a high energy consumption and a poor efficiency rating from the market.

Forming part of the European Commission’s Ecodesign Directive, which is intended to reduce overall EU energy consumption and greenhouse gas emissions by 20 per cent by 2020, the new legislation outlines a strict set of parameters which manufacturers must adhere to in order to meet the directive’s minimum efficiency requirements. Specifically, it details the maximum load and no-load losses a transformer can record based on its power output, in order to comply with the directive. A second, stricter phase of the directive is also expected to come in to force in 2021, pending a review in 2018.

The European Commission estimates that as much as 2.5 per cent of all energy consumed by the EU is wasted through transformer losses. The new directive will have a dramatic effect on reducing wasted energy on future projects and consequently both improve global carbon emissions and lower energy bills for the end-user.

Paying the price for efficiency

It is, however, hard to ignore what for many end-users is the elephant in the room when it comes to making ‘green products’ compulsory: cost.

As with many products which cut energy consumption, there is an associated cost – often due to higher material cost, advanced design and overall more effective technology. Cost is of course an important factor; however an investment should be viewed as exactly that, and looked at in the context of a transformer’s total lifetime cost (TLC) rather than just initial purchase price.

In reality, operational costs actually equate to 80 per cent of a transformer’s TLC. Under the Ecodesign Directive’s stricter design specifications on maximum load and no load losses, the subsequent energy savings made by compliant ‘green’ transformers will take a relatively short time to recover the initial increase in purchase price.

As such, this new directive should provide great impetus for anyone with an ageing power distribution system – even those that have not yet finished their expected operational life – to consider upgrading to compliant transformers as soon as possible.

A further point to bear in mind is that with rising electricity costs set to continue steadily well into the future, the cost of running a transformer will inevitable also increase. As so much of a transformer’s TLC is determined by operational costs, ensuring that the most ‘green’ product possible is chosen will undoubtedly keep running costs to an absolute minimum.

Demystifying dates

Currently causing some confusion in the market place is the cut-off point for purchasing compliant transformers.

Put simply, any transformer to be supplied after 1st July 2015 has to adhere to the requirements of the new directive. However there is an exemption if the transformers were purchased under a framework agreement and the contract for supply of the transformers was signed before 11th June 2014, as that is the ‘entry into force’ date of the regulation. In these cases the transformers supplied are exempt from the 2015 amendment to the Ecodesign Directive.


In short, the EU has rightfully identified transformers as a fundamental area of energy consumption which has significant scope for improvement. By placing specific requirements on the maximum load and no-load losses of a transformer, and preventing those that do not comply from entering the market, we will quickly start to notice a significant reduction in both energy consumption and therefore bills.

As with many new products that are introduced to tackle poor energy efficiency, there is an inevitable premium attached to cover the superior build quality and materials used. However in the context of a transformer’s total lifetime cost, the purchase price can be recovered after a relatively short time as a result of operational efficiency.

Given their integral nature to any building’s power distribution, any efficiency improvements made related to transformers will be magnified over the lifespan of a building.

The amended directive lays the foundations for massive end-user energy savings and I would urge anyone with an ageing power infrastructure to conduct a review and think seriously about taking the step forward into a cleaner, greener, and cheaper form of power distribution.