I came across this article about power supply efficiency the other day while researching power supplies. It is quite the informative read, I highly recommend it!
In the early 1990s, it was estimated that there were more than 1 billion external power supplies active in the United States alone. The efficiency of these power supplies, mainly utilizing linear technology, could be as low as 50% and still draw power when the application was turned off or not even connected to the power supply (referred to as “no-load” condition).
Experts calculated that without efforts to increase efficiencies and reduce “no-load” power consumption, external power supplies would account for around 30% of total energy consumption in less than 20 years. As early as 1992, the U.S. Environmental Protection Agency started a voluntary program to promote energy efficiency and reduce pollution that eventually became the Energy Star program. However, the first mandatory regulation dictating efficiency and no-load power draw minimums wasn’t put in place until 2004. The following section traces the path from the CEC’s 2004 regulation up to the current standards that are in place today.