EDS Technologies

Green Workstations Save Money

Save Money with Energy Star 4.0, EPEAT Gold, and 80 PLUS Energy-Saving Technologies

By Robert Green, Cadalyst Contributing Editor

Okay, I know that you may be asking why a publication for CAD
technologists would be talking about environmental concerns. You may
also wonder what Energy Star 4.0, EPEAT (Electronic Product
Environmental Assessment Tool), and 80 Plus are all about—and why
you should care.

In this edition, we’ll examine how HP is using these new energy-compliance guidelines and technologies to make its workstations some of the greenest on the market. And, since a greener workstation allows you to reduce the energy consumption of your computing environment, you’ll save money on power—and pay for your new workstations with the savings. Interested? Of course you are.

Find the Waste and You’ll Save
I like to think of energy efficiency as simply reducing energy waste. By finding and eliminating waste in your computing environment, you’ll automatically increase efficiency—and savings. And I’ve never seen anyone, environmentalist or not, who’s against saving money. In fact, I’ve found that a purely financial argument for green machines gets the attention of senior management!

So, how does a typical office computer generate waste? How might new energy efficient technology help you save? To answer these questions, we’ll examine various conditions that cause waste and discuss how new technologies address energy efficiency.

How Much Power Do Computers Use?
Before we look at waste, let's consider how much power a typical computer uses. Computers don't consume 100% of their maximum rated power all the time. In fact, power usage is variable and depends on the machine's configuration and the software currently running, as well as the user's habits (like taking frequent breaks or keeping many windows open at once). When a computer is set to idle (see below), it uses much less power than when it's in active use. It's hard to say what's typical, but a computer might use, for example, 20-25% of its maximum power rating when it's in an idle state and about 70% when it's active.
What this means is that a workstation with a power rating of 1000 watts may actually consume only 700 watts when it's being used and 200-250 watts when it's idle (of course, that's without taking into account waste by the power supply, described below). If you can guess how often a computer is in either state, you can make a very rough estimate of the cost of running the computer with this formula:

Cost per year = Hours on per year * kW consumed * Cost/kWH

Below I use calculations to show how much money you might save by adopting these power-saving technologies. To make things simple, these calculations assume 100% power usage, which may not be realistic for your situation. You may want to assume 80% or less, depending on some of the variables mentioned above, and rework the calculations to come up with a more accurate estimate of your own potential cost savings.

Waste: The Power Supply
Waste starts at the wall outlet when you plug in the computer’s power supply. The power supply converts the AC from your building’s power grid into the regulated DC power required by your computer’s internal circuits. Since the power supply is first in the chain of energy consumption, any inefficiencies are carried through the entire computer.
So if your computer's power supply is only 65% efficient, you’ll always waste 35% of the power your computer consumes. (Waste is simply 100% minus your power supply’s efficiency.) Even in computers that have power-efficient components, an energy-efficient power supply will give you the biggest bang for your buck.

Savings: The 80 Plus Power Supply
To address power supply efficiency, the 80 Plus program (notice the logo below) provides certification for all power supplies that achieve 80% efficiency under all load environments. If you equip your computers with an 80 Plus power supply, you’ll save money—it’s that simple.

The 80 Plus logo denotes the highest power supply efficiency in the business.
Go to www.80plus.org to learn more.

Let’s perform a quick cost-saving calculation on a server class machine running 24/7 in a server room. Since servers have many more components, they have large power supplies and consume a good bit of power. Here’s how the calculation looks for an older server with a 65% efficient 1000 watt power supply:

· Cost per year = Hours on per year * kW consumed * Cost/kWH
· For a machine on 24/7, hours per year is 24 hours/day * 365 days/year = 8760
· Computer power consumption = 1000 watts / 65% = 1538 watts = 1.54 kW
· Total cost = 8760 hour/year * 1.54Kw * $0.09/kwH = $1214/year

Here's how the calculation looks for an 80% efficient power supply:

· Computer power consumption = 1000 watts / 80% = 1250 watts = 1.25 kW
· Total cost = 8760 hour/year * 1.25Kw * $0.09/kwH = $986/year

Conclusions: Power Supply
The case above illustrates the importance of 80 Plus power supply technology in the following ways:

At 100% power usage, you can save $227 a year in power costs simply by using an 80 Plus power supply in your server computers! And if the power supply alone can make this much difference in cost per year, imagine what it could save over two to three years!
Workstation machines usually consume roughly one-third the power of a server, so good savings can be obtained on power costs by replacing older computers for newer ones with 80 Plus power supplies.
Of course not all machines are always at 100% power usage, so you may want to rework my calculations based on how heavily accessorized your workstations are. 80% utilization seems to be a good number for moderately configured workstations.

Waste: Machines Left On
As users, one of the biggest wasters of energy is our tendency to leave our machines on. This type of energy waste falls into a few categories, which I’ll demonstrate with a sample calculation:
Machines left on all day and night: Many users simply leave their machines on all the time without using sleep or hibernation modes supported by Windows XP and Windows Vista. These machines consume full power, as all circuit boards and disks are powered up 24/7, likely for no good reason. For a standard desktop machine with a 550-watt power supply operating at 80% efficiency in a location where electricity costs $0.09/kwH, the cost per year can be computed this way:
· Cost per year = Hours on per year * kW consumed * Cost/kWH
· For a machine on 24/7, hours per year is 24 hours/day * 365 days/year = 8760
· Computer power consumption = 550 watts / 80% = 688 watts = 0.69 kW
· Total cost = 8760 hour/year * 0.69kW * $0.09/kWH = $544/year
Machines left on all day: If your users turn off their computers at night but leave them on all day, the power costs would be:
· Cost per year = Hours on per year * kW consumed * Cost/kWH
· At 10 hours on per day the hours per year is 10 hours/day * 260 days/year=2600
· Computer power consumption = 550 watts / 80% = 688 watts = 0.69 kW
· Total cost = 2600 hour/year * 0.69KwH * $0.09/kwH = $162/year
Conclusions
A couple of conclusions really pop out from this waste analysis, namely:

Even with a highly efficient 80 Plus power supply, leaving machines on all the time costs big bucks!
Leaving machines on all day costs a lot as well, but simply turning the machine off on nights and weekends makes a big difference.

Now that you have a working knowledge of how much money you’re spending on power, you should be motivated to cut your power consumption, right?
Savings: Energy Star 4.0
So, if computers consume so much power (and money) by remaining in a powered-up state, what can we do to cut that consumption? The quick answer is to purchase computers that are Energy Star 4.0 (notice the logo below) compliant.

The Energy Star 4.0 logo denotes a computer with hardware that saves anywhere from 30% to 75% from the fully powered state, depending on which mode (standby or hibernate) is being used.

Energy Star 4.0 compliant machines save energy by controlling the computer automatically to move into lower power consumption states using the power saver features of your operating system. By shutting off disk drives and monitors after intervals of inactivity, the user doesn’t have to think about energy savings at all.

Idle	Standby (S3 State)	Hibernate (S4/Off State)
Lower energy consumption state where the operating system stays running without applications	Condition where the hardware and OS are put into a suspended state, but can be awakened quickly to resume computing	"Off" condition where a bare minimum of power is used

Power states defined by Energy Star.

The power down states (notice the figure above) range from standby (for short intervals of savings) to hibernate (for long periods like overnight). The possible savings you can achieve can be illustrated with a few sample calculations.

For an office worker who is away from a machine two hours a day, the standby mode will save a minimum of 30% of the power that would otherwise be consumed. This equals a savings of 0.6 hours of operation per day. The adjusted cost calculation would be:

Machines left on all day: If your users turn off their computers at night, but leave them on all day:

· Cost per year = Hours on per year * kW consumed * Cost/kWH
· At 10 hours/day, the hours per year is 9.4 hours/day * 260 days/year = 2444
· Computer power consumption = 550 watts / 80% = 688 watts = 0.69 kW
· Total cost = 2444 hour/year * 0.69KwH * $0.09/kwH = $152/year ($10 savings)
Note: $10 indicates the savings per year versus a machine that uses full power all day at $162 per year.

For an office worker who is away from a machine two hours per day, but leaves the machine on at night, the standby mode will save 30% of the power that would otherwise be consumed during those two hours. The hibernation mode that would shut the computer off at night would save a tremendous amount of power that would have otherwise been wasted. The same calculation would yield the following savings as compared to a machine left on at night. The adjusted cost calculation would be:

Machines left on all day: If your users turn off their computers at night, but leave them on all day:

· Cost per year = Hours on per year * kW consumed * Cost/kWH
· At 10 hours/day, the hours per year is 9.4 hours/day * 260 days/year = 2444
· Computer power consumption = 550 watts / 80% = 688 watts = 0.69 kW
· Total cost = 2444 hour/year * 0.69KwH * $0.09/kwH = $152/year ($392 savings)
Note: $392 indicates the savings per year versus a machine uses full power all day and all night at $544 per year.

Waste Heat
The bottom line is that electrical circuits are not 100% efficient and waste heat is the major power loss in the equation. If you’ve ever sat with your laptop on during a long plane ride, or sat in a confined space with a workstation running at full bore, you’ve experienced waste heat personally.

As a mechanical engineer, I can tell you how much waste heat from office equipment impacts building design. In most office buildings, some form of air conditioning must be used to keep office spaces dehumidified and at comfortable temperatures. The less heat introduced into the building space, the less air conditioning must be used—and therefore savings can be achieved.

For the purposes of design, a human being in an office environment is considered to emit 120 watts of waste heat. Yet an old computer with a 65% efficient power supply and tube monitor can easily emit 400 watts per day—as much as three additional people! And that 400 watts of heat must be offset by a similar amount of air conditioning, therefore raising your electrical usage by the same amount as the power supply wastes. So, inefficient computing equipment costs you—twice!

By reducing the power consumption of your equipment, you’ll save money on power as well as electricity for air conditioning loads. If you live in a hot part of the world, this savings is not trivial!

EPEAT Certification
In an effort to purchase energy-efficient computers, one could consider EPEAT (Electronic Product Environmental Assessment Tool). EPEAT offers Bronze, Silver, and Gold level certification (with Gold being the highest). Simply look for the EPEAT Gold logo (as seen below).

The EPEAT Gold logo assures maximum power savings.

HP Workstations like this 4600 are all EPEAT Gold certified.

You can learn more about EPEAT at www.epeat.net, but you’ll find that all HP workstations are already EPEAT Gold certified. HP is the first computer company to achieve this recognition. By purchasing EPEAT Gold certified equipment, you’ll be assured that you’ve got the greenest computer you can purchase.
Wrapping Up
I hope this educational look at power fosters great strides in efficiency and cost savings for you.

So now you can tell your boss that the nice new HP workstation you want can actually help pay for itself in energy savings.
All the best in getting your new machines!

About the Author
Robert Green performs CAD and document management programming and consulting throughout the United States and Canada. He is a popular public speaker and holds a degree in mechanical engineering from the Georgia Institute of Technology. Check out his Web site at www.cad-manager.com or e-mail him at rgreen@greenconsulting.com.