Improving energy efficiency in the home

Measurement of standby power

By Morand Fachot

Standby power, the electricity used by appliances and equipment while they are in a standby mode or even when they are switched off in some cases, makes up a significant share of the residential electricity used in modern homes. Standby power is estimated to account for 5 % to 15 % of all household electricity usage in highly-developed economies. According to the IEA (International Energy Agency), it is responsible for 1 % of global CO2 (carbon dioxide) emissions, or about 240 million tonnes of CO2 every year.

Better off in Off mode than in Standby! Better off in Off mode than in Standby!

In 1999 the IEA launched the One-Watt Initiative, an energy-saving proposal aimed at reducing standby power use in all appliances to just one watt. Many regions and countries, such as the EU (European Union), the US (United Sates), Australia, Japan and South Korea have adopted this benchmark and even, for some, introduced lower limits.

At the October 1999 IEC General meeting in Kyoto, Japan, IEC TC (Technical Committee) 59: Performance of household and similar electrical appliances, set up an ad hoc group on standby power. TC 59 formed WG (Working Group) 9 in 2001, which became MT (Maintenance Team) 9: Measurement of standby power, in 2005.

Vampire power

A number of devices, such as security systems or fire alarms, require standby power for security reasons. Others, like timers or programmable thermostats, use standby power to help reduce total electricity consumption, and standby power is therefore essential to their operation.

However, the advantages of standby power for many other appliances are less clear-cut. Standby power consumption may seem insignificant when devices are considered individually, but it is the widespread introduction in households of multiple pieces of equipment using standby mode — white goods such as microwave ovens and dishwashers, and AV (audiovisual) equipment like television sets, set-top boxes and DVD players, and computers — that makes standby power (also often called vampire power) such a major issue.

Many modern electric and electronic devices are in standby mode most of the time and are never fully turned off, or cannot be totally switched off without being unplugged. Over a year, the average microwave oven uses more energy powering its digital clock than it does cooking food.

Recognizing standby power consumption as an energy-efficiency issue, the IEC has been active for many years preparing International Standards to measure and reduce standby power.

Beside TC 59, another IEC TC is actively involved in preparing International Standards to measure power consumption in the consumer electronics domain. TC 100: Audio, video and multimedia systems and equipment, which established TA (Technical Area) 12: AV energy efficiency and Smart Grid applications, prepares International Standards to measure power consumption in on- and off-power modes.

New International Standards to measure standby power

Both TC 59 and TC 100 have recently published International Standards on measurement of power consumption.

TC 59 released the second edition of its International Standard IEC 62301, Household electrical appliances — Measurement of standby power, in January 2011. This second edition constitutes a technical revision, cancelling and replacing the first edition published in June 2005, which was used worldwide. Edition 2 delivers an improved test method for measurement of standby power.

In April 2011 TC 100 issued IEC 62087-BD ed3.0, Methods of measurement for the power consumption of audio, video and related equipment, an International Standard prepared by its TA 12. This third edition cancels and replaces the second edition, published in 2008, and constitutes a technical revision. However, unlike IEC 62301, this International Standard also covers consumption in on- and off-power modes.

Both International Standards specify methods of measurement of the electrical power consumption for the relevant white goods and AV equipment in standby mode.

The IEC listed reducing standby power as one of its recommendations regarding energy-saving technologies in its "Coping with the Energy Challenge" White Paper published in September 2010. In allowing more precise measurements of standby power, these revised International Standards will undoubtedly help the industry produce household appliances and systems offering lower standby power consumption for the benefit of consumers, the economy and the environment.

Microwave: more power used for the clock than for the cooking Microwave: more power used for the clock than for the cooking
Better off in Off mode than in Standby! Better off in Off mode than in Standby!
Laptop charger/adapter Laptop charger/adapter