Energy efficiency for external power supplies (EPS)
Controlling the power consumed by external power supplies, whether when they are supplying power or when disconnected from the load, is important for continuity of the energy supply and reduction of environmental impacts. Legislation and targets are set for external power supplies because of proliferation, lack of on/off control and because they are commonly left connected to the mains supply when not in use.
Many areas around the world have introduced legislation for no load power consumption and active mode efficiency for external power supplies.
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 which 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 which 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.
In recent times both the US DoE and the EU CoC have set new, more demanding, standards for both energy efficiency and no load power consumption. The EU CoC has also introduced a 10% load efficiency requirement reflecting applications which spend a large proportion of time using minimal power from the external power supply and has two tiers to drive future development.
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 tables (listed in Efficiency Legislation for EPS 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. Devices that require Federal approval as a medical device are exempt from the new DoE legislation.