The US Environmental Protection Agency (EPA) has estimated only a tenth of the 18 million students in the USA currently using desktop PCs set their desktops into power-saving mode.

The EPA estimates that for every 1 percent of US students using desktop power-saving modes, an additional 30,000 tonnes of CO2 emissions are saved a year, equivalent to taking over 5,700 cars off the road. That would be 350,000 tonnes saved annually if 61 percent of US students did so.

Unlike businesses, which may use automated power management software from Verdiem or 1E, student systems are generally left running unless students switch them off or use power management software to set them into low power modes.

Relying on students to voluntarily set PCs to save power when inactive isn’t particularly certain; the students don’t own the PCs and don’t pay the electricity bill. Business users can’t be relied upon to switch PCs off over-night, nor do they generally use power-saving operating modes in the day-time.

“Most IT departments set the power management to a company standard,” said Sandy McCaskie, MD for EMEA at General Dynamics Itronix, a maker of rugged laptops. “In the commercial world vendors tend not to set power saving as they like their unit to perform at maximum speed.”

A way of saving power is needed that doesn't compromise performance but avoids wasting power when PCs are inactive.

Sure-fire power-savings

New Energy Star requirements, introduced in June by the EPA and US Department of Energy, will help. Energy Star v4.0-compliant PCs will be up to 65 percent more power-efficient than non-compliant ones through having better power supply units, and automatically going into sleep mode if inactive for a little while. This uses a quarter of the electricity needed in operating mode.

Fujitsu Siemens Computers’ Esprimo E5615 EPA Professional PC has a power supply with an 80 percent efficiency factor, meeting the v4 Energy Star guideline. HP, Dell and Lenovo also have machines compliant with this standard.

“Fujitsu Siemens Computers already delivers customers power-saving PCs with built-in automatic switch off capability,” said Fujitsu Siemens Computers chief marketing officer, Barbara Schaedler. “Its energy-saving ESPRIMO PCs enable organisations to pre-configure and set various automatic power-saving options in accordance with the user’s needs. Parameters can be set to turn the system off entirely or to run it into standby mode once a certain time period has elapsed.”

“The ESPRIMO PC range also has a switched monitor outlet meaning that the display is powered through the PC. When the PC goes into standby mode, it can automatically turn off the monitor as well. It’s estimated that this can save up to 50 per cent of a monitor’s power consumption annually. As a company we have always tried to take a lead in green IT and can confirm that we remain committed to incorporating other power-saving elements into our future PC and notebook models.”

A desktop's screen brightness can be varied automatically so as to reduce power use in low-light conditions and thus save electricity. According to McCaskie, GD Itronix has DynaVue screen technology: “This is a major factor as it reduces power consumption without user intervention.” It focuses on contrast ratio and polarization techniques, and optimizes viewability in all lighting conditions. Naturally such technology comes at a price.

Another way to cut desktop power use is to substitute thin clients for PCs. Neoware claims desktop PCs consume up to 280 watts of power, whereas its most power-efficient thin clients use just 30 watts in the same period, a nearly 90 percent saving. Replacing 3,500 such desktops with thin clients could save a UK business or university £160,000 annually, with electricity costing £0.0722 per KW/hour.

Windows Vista has better power management features than XP, for example a default ‘Sleep’ mode which is automatically activated after one hour of non-use. Microsoft claims Vista could help reduce the carbon dioxide generated by an organisation with 200 desktops by up to 45 tonnes per year. That could mean savings on energy bills of up to £46 per PC per year. If the organisation’s volume Vista purchase discount is high enough, then this could justify a Vista upgrade on its own.