Looking for a new computer? You may want to look for those that meet the new Energy Star 5.0 version for energy-efficient computers and monitors.

The new efficiency standards for desktop and notebook computers go into effect July 1, 2009, while those for computer displays under 30 inches goes into effect Oct. 30 and standards for displays of 30 to 60 inches take effect on January 30, 2010.

Yes, there are two different requirements for computers and monitors, and several upgrades to the previous Energy Star 4.0 version.

For a computer to be listed as an Energy Star model and bear its logo, there are idle, sleep, standby, power supply and power management requirements, as well as on-mode power consumption requirements based on formulae. Several different categories of computers are included, with those for more robust notebooks with two-core systems (like Intel’s Core Duo processors) and desktops with four cores or 4GB of system memory added this time.

Power management requirements include shipping a computer set to go into sleep mode within 30 minutes or inactivity and integrated or notebook computers display modes to go to sleep after 15 minutes—though you can set your system to go to sleep even sooner.

The new 5.0 spec for computers uses Typical Energy Consumption (TEC) for a standard. That means desktops and notebooks must meet an annual electricity use estimate, measured in kilowatt-hours (kWh) and scaled by an assumed typical usage model. Energy Star 5.0 desktops must use 148 to 234 kWh or less, while Energy Star 5.0 notebook computers must use 40 to 88.5 kWh or less per year, depending on what category the computer or notebook is in (see below).

• Category A (All non-category B, C, D, computers and notebooks)—148 kWh desktops/40 kWh notebooks.
• Category B (2 physical cores and 2GB or more system memory)—175 kWh desktops/53 kWh notebooks.
• Category C (More than two physical cores and 2GB or more system memory or a discrete GPU (graphic processing unit)—209 kWh desktops/88.5 kWh notebooks.
• Category D: Four or more physical cores and 4GB or more system memory or a discrete GPU with frame buffer width greater than 128-bit—234 kWh desktops.

Requirements for power supplies in computers was upped to 85 percent efficiency of internal power supplies at 50 percent and 82 percent efficiency at 20 percent and 100 percent rated output. Computers with external power supply must meet Energy Star version 2.0 for external power supplies. These power supplies are rated at 86 percent to 87 percent efficiency, and will have a Roman numeral V on their backs.

Energy Star 5.0 monitors must meet on mode qualification as well, plus use less than 2 watts while in sleep mode and less than 1 watt while in “standby,” also known as “off.” (Many computers and consumer electronics continue to draw an electrical charge when turned off but left plugged in.)

Here are the on-mode energy requirements for Energy Star 5.0 displays:

Displays shipped with automatic brightness control can qualify for Energy Star 5.0 as well.

Small-scale servers and thin clients, as well as fax machines and scanners are also included in the new Energy Star 5.0 specifications.

Steven Castle - Contributing Writer

Steven Castle is Electronic House's managing editor. he has been writing about consumer electronics, homes and energy efficiency topics for two decades. He is also the co-founder of GreenTech Advocates.