Energy Saving Electronics

Saving energy for a better tomorrow

Standby Power in Electronic Devices

Reducing standby power to save electricity and save money

One of the most obviously ways in which electricity is wasted, is within equipment which is never completely switched off.

Many types of electronic equipment can be placed in a "standby" mode whereby they are not operating fully, but they are still consuming some power.

Some equipment does not have a true on/off switch, and can only be truly switched off by turning of the wall socket or removing the mains plug.

The increasing awareness of global warming has put energy efficiency to the forefront of public opinion, and standby power can be a significant portion of the total power consumption in both the home and the office. 

Standby power consumption is also referred to as Leaking Electricity, although this term is becoming less common.  Some people also call it to Phantom Power.

Why does equipment have a standby mode ?

The origins of the standby mode can be traced to the early days of video recorders. In order to record a program at a particular time, the VCR had to have a built-in clock and be able to switch itself on automatically.

The clock was a particular problem.  Although it became possible to design the VCR so that the clock would keep running even when the unit was unplugged, environmental regulation within Japan prevented them from fitting the rechargeable batteries necessary to do this.  This meant that Japanese VCRs had to be left permanently in standby even when no timer recording was required.  This quickly became the normal method of building a VCR.

In due course, the built-in clock started to be fitted to lots of other equipment from audio systems to microwave cookers.  The equipment could then not be disconnected from the electrical supply for more than a few minutes without loosing the clock setting.

In addition, with every type of equipment being operated from an infra-red remote control, a new form a lazyness developed.  Rather than have to get up out of a chair to turn the TV or HiFi system on, users expected to be able to do it via the remote control.

In order to respond to the remote control, the equipment could not be fully off, but had to be in standby mode.

How big is the effect ?

Although individual devices are likely to consume only a few watts each in standby mode, the fact that they consume this power all of the time results in substantial electricity consumption over a year.

As a percentage of average total consumption in the home, the figures vary from country to country, but are typically around 500kW-hrs equivalent to about 10% of total consumption.  

Figures from the Energy Saving Trust on standby power use in UK homes suggest that Stereos on standby cost £290m ($580m), VCRs and DVDs cost £194m ($390m) and TVs on standby cost £88m ($180m).

In terms of CO2 emissions, in the UK alone, our equipment on standby produces a total of 3.1 million tonnes of CO2 each year.

Methods of reducing Standby Power

Much of the equipment that is left in Standby mode could actually be switched off completely.  Most DVD recorders (and even later design VCRs) can reset their timer clock when they are switched back on by reading the time from TV signal.

Digital radios using HD Radio, DAB or DRM can do the same thing. 

This eliminates the old problem of having to laboriously reset the clock by hand whenever the power was disconnected.

Despite this, most DVD recorders, PVRs and digital TV receivers still expect to be left in standby rather than completely turned off.

Obviously standby mode will be needed if a timer recording has been set up, but there is another reason as well.  Digital receivers normal incorporate an EPG facility (Electronic Program Guide).  This needs to be updated at the times that the broadcaster chooses, and not necessarily when the unit is turned on.

In practise, the EPG will normally update quickly enough to avoid inconveniencing the user, and so complete disconnection of the power remains a viable option.

Some DVD recorders and VCRs have an "economy" mode which can be set from the menu options.  When enabled, the clock display is turned off when the unit goes into standby, reducing (though not eliminating) power consumption.  

There are two main ways of reducing standby power in these types of devices - manually and automatically. 

Manually means "turning things off yourself", i.e. getting up out of the chair and turning things off with the power switch (if there is one) or using the switch on the wall socket.

Automatically means using some form of device that automatically disconnects the equipment  when you set it to standby using the remote control.

There are three main types.

One type senses the reduction in electricity consumption from the device when it is put into standby and then, after a short delay, disconnects the power altogether. Power is restored by pressing a button on the socket.

Another type, designed primarily for PCs, has a master socket into which the PC is plugged, and peripheral sockets from which the monitor, printer etc. are powered.  When the PC goes to standby, the peripherals are automatically turned off, but the device connected to the master socket remains powered, and power to the peripherals is restored when it is turned back on..

A third type is simply a remote control switch whose purpose is to allow the user to turn off the power socket without leaving their chair. 

Future Developments

Manufacturers of electronic equipment are very aware of the problem and are under considerable pressure from government agencies and consumers to improve overall efficiency and reduce standby power consumption.

Televisions, in particular, have shown great improvements recently with some of the latest TV sets offering standby power consumption of less than 1 watt. 

 

standby button

 

 


Stack of equipment on Standby

Stack of equipment left in Standby mode.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Automatic switching socket

Automatic shutdown socket