Stand by Me (Efficiently)
Standby power, of course, refers to the electricity consumed by an appliance while not performing its primary function, in other words, when the unit is switched off. Products with continual displays (microwaves, ranges, etc.), remote control circuits (televisions, VCRs, garage door openers, etc.), battery chargers (cordless vacs, power tools, etc.), or sensor-based systems for continuous monitoring (security systems, HVAC, etc.), all draw small amounts of energy in their inactive mode.
Recently, the issue of standby power was examined from four different perspectives during a special panel session at the 51st International Appliance Technical Conference, held May 8-10 in Lexington, Ky.
An overview of the topic was presented by Alan Meier, staff scientist, at Lawrence Berkeley National Laboratory, Berkeley, Calif. After giving a visual tour of products that draw standby power in a typical home, Meier singled out a specific model of compact stereo that draws 27 watts while on and 25 watts while off. "With levels like that, why did they even bother to install an on/off switch?" he quipped.
While not all appliances use that amount of standby power, even lower levels can still have a big cumulative impact due to the sheer number of products in the house using such power. Reporting from his research, Meier said that standby power usage adds up to about 50 watts in an average home. On a larger scale, he says that standby power may be responsible for up to 5 percent of electricity consumption in the U.S., and up to 10 percent to 15 percent in Japan and Germany. On a worldwide basis, generating electricity to serve standby power needs accounts for up to 1 percent of global CO2 emissions, according to Meier.
Meier also predicted that standby power consumption will grow much larger in the future. As examples, he cited the increasing use of electronic controls on appliances and the proliferation of set top boxes for televisions, the latter of which can draw between 8 watts to 40 watts each.
Seeing excessive standby power consumption as a waste of energy, Meier recalled his1998 proposal of a global plan for reducing standby power in an appliance to1 watt or less. (More of Meier's research can be found at www.LBL.gov.)
Wayne Morris, vice president of the Portable Appliance Division, Association of Home Appliance Manufacturers, Washington, D.C., objected to the use of the term "waste" when referring to standby power. Morris, who has extensive government relations experience with AHAM, was speaking on behalf of an industry saddled with numerous regulations and not eager to embrace any new ones.
"It is not waste if it provides a feature that is beneficial to the consumer," he said. Remote activation, sensor monitoring, informative displays, the convenience of cordless appliances-these are all features desired by consumers. "We listen to consumers; we don't dictate to them," he added. The coming age of interconnected appliances may increase standby power usage, but it will be justified, since it will provide benefits to consumers, he noted.
In a similar vein, Edward Harrison, engineering manager, Batteries and Chargers, Black & Decker Power Tools, Towson, Md., objected to the characterization that battery chargers "waste" energy. Harrison noted that disconnected rechargeable batteries will self-discharge over time, even when not being used. He cited research showing that NiCd cells can self-discharge as much as 10 percent to 20 percent within the first 48 hours, then discharging at a lower rate thereafter. It is imperative, therefore, that rechargeable batteries remain connected to a power supply in order to maintain a full charge, because the consumer will be expecting the device to perform at a fully charged level.
These differing opinions should not lead one to think that the industry is heading toward some type of showdown over the issue. The good news is that innovative ICs for power supplies now permit the design of standby circuits that operate much more efficiently. That was the message of the last speaker, Peter Vaughan, product applications manager for Power Integrations, Sunnyvale, Calif., whose company makes the energy-saving TinySwitch IC. After reviewing the various options for power supply designs, Vaughan concluded by saying that appliance manufacturers can significantly reduce standby power consumption without sacrificing any features deemed beneficial to consumers, and that they can accomplish this with little added cost.
That sentiment can also be found in an article titled "Drop by Drop, Green Design Saves Buckets of Power," EDn magazine, February 4, 1999, written by Bill Schweber, technical editor. In reviewing a number of new generation power-saving components and circuit designs, the author says that achieving a level of 1 watt standby power consumption "should not be too difficult."
Furthermore, pressure to reduce standby power levels will likely flow from voluntary programs, such as the EPA's Energy Star program, and from market forces, rather than from new mandatory regulations. In fact, several manufacturers, including Pioneer, Sony, and Matsushita, have already voluntarily established targets for lower standby power levels. These companies recognize that, as consumers become increasingly aware of the issue, efficient use of standby power will itself be perceived as a benefit worth shopping for.