This Green Computing article will explain the history and benefits of 80 Plus, a standard that has been developed over the last six years. If you have read any of our other articles on the concept of Green Computing, then you are already familiar with 80 Plus.

This article is meant for those who are new to the standard and are wondering if they should make it a requirement the next time they buy.

What is 80 Plus Certification?

On Feb 15, 2004, EPRI (Electric Power Research Institute) and Ecos (environmental consulting) released their first draft of standardized test for calculating the energy efficiency of internal power supplies. The tests measure efficiency by comparing the real output power against the total input power. Whenever you convert AC power (from an outlet) to DC power (for computers), there is an energy overhead that is lost as heat. Cheaply made equipment doesn’t convert power well and thus produces more heat and power drain. 80 Plus was designed to promote efficiency in a market littered with PSUs that were mostly 65% efficient.

As of June 1st, 2010, There are now 2,421 power supplies that have been 80 Plus certified. The complete list of certified models can be found here. It certifies electronics that have over 80% energy efficiency at 20%, 50% and 100% of rated load. In addition to producing less heat, this also means that they waste less electricity, saving you money on your electric bill. The following table shows the minimum requirements for 80 Plus hardware.

80 PLUS Requirements 115V Internal – Non-Redundant 230V Internal – Redundant
Load Amount 20% 50% 100% 20% 50% 100%
80 PLUS 80% 80% 80% NA NA NA
80 PLUS Bronze 82% 85% 82% 81% 85% 81%
80 PLUS Silver 85% 88% 85% 85% 89% 85%
80 PLUS Gold 87% 90% 87% 88% 92% 88%
80 PLUS Platinum NA 90% 94% 91%

80 Plus Simple Benefits

• Save money with reduced power consumption
• Decreased heat output and cooling requirement
• Increased reliability and component lifespan

80 Plus - All

All are NOT Created Equal

As you can see, there are actually 5 levels of 80 Plus certification. While there are 2278 80 Plus certified desktop/workstation power supplies available, almost half of them only have the basic certification. 35% received Bronze. About 8% received Silver. About 9% received Gold. Platinum is reserved for redundant data center power supplies.

If you are comparing only basic 80 Plus certified power supplies to non-certified ones, then you are missing out on another 10% of efficiency. Since traditional power supplies were mostly 15% less efficient than 80 Plus, another 10% is quite a margin. While there are far fewer Silver certified power supplies, they will add an additional 5%-8% efficiency over a basic 80 Plus certification.

How Much Money Does an 80 Plus Power Supply Save?

This calculation will help you find out how much money you can save with a more efficient power supply.

(cost per kWh x total watts used in time period) ÷ 1000

The first big variable to consider is the cost of electricity per kilowatt-hour where you live. This cost varies by State from 7¢ to 19¢ To find out what you pay, look at your electric bill. You can also view averages on this list from the US Energy Information Administration. A kilowatt-hour refers to every 1000 watts used.

Once you know what your cost per kWh is, you only need to know how much wattage you are using. This second big variable is harder to nail down. A computer playing a video game with a big graphics card might be using 400 watts of power at times. That same computer at idle might be using 50 watts. A laptop might be using 35 watts.

For our illustration, we will say there is an average of 100 watts being used. Our computer is left on all the time. Our local power company charges 10¢ for every 1000 watts. Therefore, the calculation for yearly cost is (24 x 365 x 100 x .10) ÷ 1000. That means our test computer that uses 100 watts constantly and is on 24/7 costs us $87.60 per year.

How does 80 Plus help us here? Let’s say we need 100 watts of power output in our illustration. We can compare power consumption using different power supplies at 10¢ per kWh:

Power Supply Input Power Calculation Yearly Cost to Run 24/7/365
65% efficient PSU 154 watts (24 x 365 x 154 x .10) ÷ 1000 $134.90
80 Plus 125 watts (24 x 365 x 125 x .10) ÷ 1000 $109.50
80 Plus Bronze 120.5 watts (24 x 365 x 120.5 x .10) ÷ 1000 $105.56
80 Plus Silver 116.3 watts (24 x 365 x 116.3 x .10) ÷ 1000 $101.88
80 Plus Gold 113.7 watts (24 x 365 x 113.7 x .10) ÷ 1000 $99.60

This information should help you calculate your own savings. If you are using an inefficient power supply, You could probably pay for the cost of a new 80 Plus PSU each year in the power you waste. If you are comparing a basic 80 Plus PSU to an 80 Plus Silver PSU, your savings will usually pay for the difference in the first 2 years.

The 100 watt example could be conservative for your computer, depending on how recent it is. A PC with a Core i7 860 CPU uses 86 watts of power at idle by itself. A GTX 470 graphics card uses 33 watts at idle. Add your hard disk, mainboard, sound card, and RAM, you have a system pulling 160 watts at idle. This PC actually uses an average of 200 watts. If I use an 80 Plus Silver PSU instead of an energy hog, I will save $68 per year!

The choice is simple. Don’t throw money away and waste power. Buy an 80 Plus PSU. If this article helped you learn something, let us know by leaving a comment. Until next time!