80 PLUS

80 PLUS is an initiative to promote more electrical energy efficient computer power supply units (PSU). It certifies products that have more than 80% energy efficiency at 20%, 50% and 100% of rated load, and a power factor of 0.9 or greater at 100% load.That is, PSUs that waste 20% or less electric energy as heat at the specified load levels, thus reducing electricity use and bills compared to less efficient PSUs. Sometimes rebates are given for manufacturers who use 80 plus-certified PSUs.

History

* Ecos & EPRI develop the Generalized Internal Power Supply Efficiency Test Protocol for desktop derived multi-output power supplies
* In March 2004 the 80 PLUS idea was presented as an initiative at the ACEEE Market Transformation Symposium.
* In February 2005 the first market ready power supply was created by Seasonic.
* In 2006 Energy Star added 80 PLUS requirements to their upcoming (in effect since July 2007) Energy Star 4.0 computer specifications.
* In November and February 2006 HP and Dell certify their PSU's to the 80 PLUS spec.
* July 20, 2007 — ENERGY STAR® Computer Specification 4.0 goes into effect. The specification includes 80 PLUS power supply efficiency levels for desktop computers.
* December 2007 — over 200 [http://www.80plus.org/manu/psu_80plus/psu_join.php PSU's] on the market are 80 PLUS certified and it is becoming the market standard.
* First quarter 2008 — Standards revised to add Bronze, Silver and Gold higher efficiency level certifications.

Efficiency level certifications

For the higher certification levels, the requirement of 0.9 or better power factor was extended to apply to 20% and 50% load levels, as well as at 100% load.cite web | url = http://www.silentpcreview.com/article814-page1.html | title = 80 Plus expands podium for Bronze, Silver & Gold | author = MIke Chin | work = Silent PC Review | date = 19 March 2008 | accessdate = 2008-04-21 ]

The Climate Savers Computing Initiative efficiency level targets for workstations for 2007 through 2011, correspond to the 80 PLUS certification levels. From July 2007 through June 2008, basic 80 PLUS level (Energy Star 4.0). For next year target is, 80 PLUS bronze level, the following year 80 PLUS silver, then 80 PLUS gold.

What it means

The efficiency of a computer power supply is the amount of energy it supplies, divided by how much energy is input. The remaining energy is converted into heat. For instance, a power supply operating at 60% efficiency, supplying 300 watts to a computer would draw 500 watts, and give off 200 watts of heat. An 80% efficient supply would draw 375 watts to produce the same 300 watts, giving off 75 watts of heat.

For a given power supply, efficiency varies depending on how much power is being delivered. Supplies are typically most efficient at between half and three quarters load, much less efficient at low load, and somewhat less efficient at maximum load. Older ATX power supplies were typically 60% to 75% efficient. To qualify for 80 PLUS, a power supply must achieve at least 80% efficiency at three specified loads (20%, 50% and 100% of maximum rated power). However, 80 PLUS supplies may still be less than 80% efficient at lower loads. For instance, an 80 PLUS, 520 watt supply could still be 70% or less efficient at 60 watts (a typical idle power for a desktop computer). [cite web | url = http://www.silentpcreview.com/article692-page4.html | title = Corsair HX520W & HX620W Modular power supplies | work = Silent PC Review | author = Mike Chin | date = 17 November 2006 ] Thus it is still important to select a supply with capacity appropriate to the device being powered.

Typical computer power supplies may have power factors as low as 0.5 to 0.6.cite web | url = http://www.80plus.org | title = The 80 PLUS Program ] The higher power factor reduces the peak current draw, reducing load on the circuit or on an uninterruptible power supply.

Reducing the heat output of the computer helps reduce noise, since fans do not have to spin as fast to cool the computer. Reduced heat and resulting lower cooling demands may increase computer reliability.

The testing conditions may give an unrealistic expectation of efficiency for heavily loaded, high power (rated much larger than 300W) supplies. A heavily loaded power supply and the computer it is powering generate significant amounts of heat, which may raise the power supply temperature, which is likely to decrease its efficiency. Since power supplies are certified at room temperature, this effect is not taken into account.

80PLUS does not set efficiency targets for very low load. For instance, generation of standby power may still be relatively inefficient, and may not meet requirements of the One Watt Initiative. Testing of 80 PLUS power supplies shows that they vary considerably in standby efficiency. Some consume half a watt [cite web | url = http://www.silentpcreview.com/article813-page4.html | title = Corsair TX650W power supply review | work = Silent PC Review] or less in standby with no load, where others consume several times as much at standby [ cite web | url = http://www.silentpcreview.com/article806-page5.html | title = Enermax Modu82+ 625 Power Supply Review | work = Silent PC Review] , even though they may meet higher 80PLUS certification requirement levels. Inefficiencies in generating standby power are magnified by the amount of time that computers spend turned off.

ee also

* Climate Savers Computing Initiative
* Computer power supply
* Power management
* Green computing
* Quiet PC
* Performance per watt

References

External links

* [http://www.80plus.org/ 80 PLUS] — official website
* [http://www.dvorak.org/blog/?p=17011 Saving Power] - Article on power saving techniques