External power supplies & energy efficiency legislation

Gary Bocock
XP Power
Power supplies must conform to energy legislation limits
Gary Bocock, looks at how legislation is changing the requirements for energy efficient operation of power supplies across the world.

Energy efficiency legislation for External Power Supplies (EPS) is in place across most regions of the world. The focus of these regulations is on the average active mode efficiency, measured at 25%, 50%, 75% and 100% of full load, and the no load power consumption. Driven by the environmental impacts of leaving power supplies always turned on despite the load not being in use, legislation sets limits for what is considered to be a viable no load power consumption. Controlling the power consumed by external power supplies, whether a load is connected or not, delivers significant reduction in the environmental impact.

In the USA there are a number of bodies legislating on energy efficiency; the California Energy Commission (CEC), US Congress with its Energy Independence and Security Act (EISA) and recently the United States Department of Energy (DoE). There is also Energy Star that sets limits for electrical and electronic equipment.

In Europe there is the Energy related Products (ErP) Directive formerly known as the Energy Using Products (EuP) directive, which is mandatory. There is also the EU Code of Conduct for external power supplies that is voluntary.

In Canada there is Natural Resources Canada (NRCan) and in Australia the Minimum Energy Performance Standard (MEPS).

These are a just a few examples of mandatory requirements written into legislation.

Recently both the US DoE and the EU CoC have updated their energy efficiency standards. These changes, apply to both the no load power consumption limit and the active mode operating energy efficiency. At the same time the EU CoC has added an efficiency requirement intended for those applications where, for most of its operating time, the load consumes a relatively small amount of power from the external power supply, requiring the power supply to meet an efficiency target at 10% load. The new standard has two tiers intended to assist in defining new developments.

The DoE and EU CoC were both introduced in early 2014 with both the DoE and EU CoC tier 2 requirements coming into force in 2016. These new requirements mean both increased active mode efficiency and reduced no load power consumption. The legislation is aimed at consumer products, due to proliferation, and specifically excludes devices that require Federal approval as medical devices and product known as an “indirect power supply” which cannot operate the end equipment without the addition of a battery.

 The tables below outline the differences between the level IV and level V limits previously invoked, the new DoE level VI limits and the EU CoC tier 1 & tier 2 limits with implementation dates. Notably the DoE limits now incorporate external power supplies with an output power greater than 250W.


Figures for the efficiency requirements for power supplies at different power levels as defined by DOE




Figures for the efficiency requirements for power supplies at different power levels as defined by EU




Figures for the efficiency requirements for power supplies at different power levels as defined by EU




Figures for the efficiency requirements for power supplies at different power levels as defined by Energy Star


Delivering energy efficient appliances to the market has become a key marketing requirement. Energy tariffs have increased significantly over the past years and together with increasing government energy awareness and security initiatives, consumers and business buyers alike have energy efficiency as a key selection criterion. Power supplies with Level VI ratings are now already available and as we move into early 2016 we will see an increase in products being released that comply with these latest energy efficiency standards

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