EnergyStar Computer Spec 4.0 Finalized

Table of Contents

Since 2005, SPCR has been eagerly anticipating the new EnergyStar 4.0 specifications for computers. As reported in our March ’05 article, “A New Energy Star… in 2007“, the EPA proposed tough new targets for both operational and idle power consumption. After nearly two years of revisions and industry consultations, the final spec has finally been delivered. How has the new spec been changed since the original proposal, and how will it affect the industry and the computer consumer when it comes into effect July 20, 2007?

November 21, 2006 by Alec Ross

Editor Note: Alec Ross, currently enrolled in the CS program at the University of Toronto, usually hangs out in the SPCR newsroom. Working on this story, Alec found so many changes from the original proposal for the new ES computer specification that it quickly ballooned into a full article. Energy conscious readers will find his report very interesting, as will those who like to follow industry politics.

Mike Chin

The U.S. Environmental Protection Agency was created in
1970, with the grand mission of "protecting human health and the environment." In 1992, it
introduced the EnergyStar program for computers and monitors, which expanded
over the 1990s to include over 50 additional categories. EnergyStar is a
voluntary program: In exchange for meeting the EPA’s efficiency targets,
companies get to use the familiar star logo, and receive favorable treatment
when bidding on government orders.

The previous standards, which came into
effect on July 1, 2000, required only that the computer have an automatic “sleep
mode” during which it could consume up to 30% of it’s maximum AC power,
depending on the size of the power supply. As a result, over 98% of computers
shipping today bear the EnergyStar logo. One of the goals of the new
specifications was to reduce that number — in effect, to make certification
something that only the cream of the crop can boast of having. The new Energy Star Computer Specification, Version 4.0, will become effective July 20, 2007.

The new standards have undergone a number of revisions, as reported by Mike Chin
in his article “The State of the Industry,
March 2006: Through Silent Eyes
“, based on feedback from industry
representatives such as Hewlett Packard, ATI and Intel (all of which are
on the EPA’s website
.) These revisions have been fairly extensive, which is why you
get a whole article instead of a news post. Their net effect? As you may have
guessed, after industry had their say, the certification was loosened and expanded quite a

First, the big question: How efficient does a computer need to be to qualify for
Well, it depends what kind of computer we are talking about.

There are no fewer than six
classes of computer under the new EnergyStar. This is the largest single change
from the original plan, which called for one level of efficiency for all
desktops, one for all notebooks, and so on. In the final spec, each different class has different
feature and efficiency requirements. Some, such as dedicated servers, blade
units and palmtops, aren’t included at all.

are a couple of constants across every type and tier:

  • Sleep Mode: Computers are still
    required to enter sleep mode automatically after 30 minutes by default (except
    for servers, which are generally working 24/7).
  • Power Supply Efficiency: External power supplies must
    exceed 84% efficiency. More importantly, internal power supplies must have a
    power factor over 0.9 at 100% load, and an efficiency rating of at least 80% at
    the 20%, 50%, and 100% load levels. This is a major victory for efficiency
    and, by association, low noise.

At present, the minimum efficiency for an ATX 2.2
power supply is 68%, and power factor regulation is entirely voluntary in the
US. While Ecos Consulting’s 80-Plus program was well-received at SPCR, its
visibility to the mainstream media and consumers was initially low, though
this has changed in the last few months with EnergyStar’s adoption of
the standard. With this specification, power supply efficiency has been vaulted
into the spotlight, and the fine folks at Ecos should give themselves a
well-deserved pat on the back. The power factor correction is icing on the cake;
not only will computer power supplies be more efficient, they will also put less of a
strain on electricity grids.

The table below summarizes the EnergyStar Final Computer Specification, Version 4.0, which can be downloaded at

Summary of EnergyStar 4.0 Specifications
– effective July 20, 2007

Computer Type

Idle Power

Sleep Power

Standby Power


Power Factor


Category A Desktop Derivatives






Standard Desktops

Category B Desktop Derivatives






Dual-Core Systems with 1GB RAM

Category C Desktop Derivatives






Gaming/Heavy Multimedia Systems

Category A Notebooks + Tablets






Most Laptops

Category B Notebooks +






Laptops w/ 128MB Graphics Memory







Commercial Workstations

There are a few points in the table above that bear additional clarification:

derivatives” include actual desktops, desktop-derived servers, integrated
computers and game consoles. 

Workstations have their own special set of
rules based on “Typical Electricity Consumption”, or TEC, which is 35% of the
maximum power supply output plus 1.75 watts per hard drive. The maximum idle,
sleep and standby power ratings are then determined by the TEC; if the formula
(0.7*Idle +0.2*Sleep +0.1*Standby) is less than the TEC, the model qualifies.
This gives integrators some wiggle room- a slightly worse efficiency at idle can
be compensated by better efficiency while sleeping. Compared to desktop
derivatives, this seems like a pretty low target — a computer with a 400W power
supply and two hard drives has a TEC rating of 143.5W. When you consider all the
equipment on the list to qualify as a workstation, however — ECC memory, discrete
graphics, multiple processor sockets — the reason for the high power allowance
becomes clear.

How tough are these targets?

The category A desktop target is fairly demanding by current standards. The only modern PCs SPCR has evaluated that idle below
50W are VIA Mini-ITX systems, or desktop systems using mobile CPUs.
SPCR’s Athlon64-based lab computer draws 51W when idling, just slightly
off-pace. According to most review sites, Intel’s flagship Core 2 Duo
draws more power at idle, which likely puts it out of the running. There
are, of course, a number of other options: AMD’s Athlon64 EE HTPC variant will
afford a bit of headroom by using only 35W at peak, Intel has a slew of mobile
chips all the way down to 9W, and VIA’s systems would nearly all fit in under
the limit — not to mention Transmeta’s Efficeon, AMD’s Geode, and so on. Many of
these would make for a very efficient system, at least without too much in the
way of RAM, graphics power, and so on.

Power supply sizing will also play a factor in meeting the spec. Most power
supplies drop off drastically in efficiency below 20% load, and if the system is
to idle at 50W, a 400W or 500W power supply just isn’t going to be efficient
enough. In the same vein, and as MikeC mentioned in his first article,
motherboard efficiency is suddenly much more important. If it’s optimized to
deliver 130W to the CPU, the motherboard will likely have trouble with
efficiency when idling at 10W or 20W.

What sort of impact will this new specification have?

First of all, the
EnergyStar logo is going to mean something again. If you buy a certified system,
you will be getting one of the most efficient systems in it’s class.

Second, it is likely to increase the overall efficiency of computers in general.
The US government, one of the largest system buyers in the world, uses
EnergyStar certified machines almost exclusively. Most large computer
integrators have already committed to offering certified products by the time
the new specifications come into effect. Hopefully the huge market represented
here will spur imitation and innovation, and some of these gains will trickle
down into the majority of systems and components. Perhaps in a few years, this
standard will be just as meaningless as the current one, met by the vast
majority of computers on the market.

The original compliance target for the new standards was 20-25% of all new systems. With the spec now complete, and somewhat less stringent, has that target changed at all? The EPA states that the levels included in the final spec

"…translate to an overall 24.4% qualification rate based on EPA’s dataset. This dataset represented existing and next generation platforms and was based on manufacturer data and data gathered through EPA testing. The qualification rate is slightly lower for desktops and slightly higher for notebooks."

How many units would comply for the new certification if it were implemented today? The EPA response:

"Many existing models are able to meet the idle, sleep, and standby requirements today. However, a more limited set of models will also meet the ES internal power supply efficiency requirements. Just last week a major manufacturer announced the intention to release a selection of products that would meet all aspects of ES 4.0 requirements six months before these requirements become effective. EPA estimates that at least 25% of total products sold will meet the ES requirements once they are effective July 20, 2007."

Finally a bit of marketing PR about the new specification from EPA:

"The new ES specifications for desktop and notebook computers and related equipment that are expected to save U.S. households and businesses more than $1.8 billion in energy costs over the next 5 years and avoid greenhouse gas emissions equal to taking more than 2.7 million cars from the road. [Editor’s Note: To put this in perspective, there are ~270 million cars on the road in the US today.] If every computer purchased by businesses meets the new ES requirements in effect next year, businesses will save $1.2 billion over the lifetime of their new computers, equal to lighting 730 million square feet of U.S. commercial building space each year. Government agencies buying ES will also garner big savings. If the government sector buys only computers that meet the new ES requirements, this sector will save nearly 3 billion kWh each year and reduce greenhouse gas emissions by 4.4 billion pounds each year."

There are some major disappointments.

With the creation of so many categories, the significance of the Energy Star logo is much less meaningful than the original proposal, which was simple and effective: "If a computer bears the logo, it draws <60W at idle".

The biggest disappointment is that there is no differentiation in the labeling for different classes of ES certified computers. In our view, awareness of the classification is critical. Here’s an example of why:

Even if a gaming machine qualifies as an EnergyStar under Category C, it could still use nearly twice as much power at idle as a standard desktop that doesn’t qualify under Category A. To be specific, a gaming machine that draws 95W qualifies for EnergyStar while a standard desktop that draws 51W does not qualify. There is no difference in logos to tell a consumer which class a particular EnergyStar product belongs to, even though the requirements vary so widely.

(This also has the effect of actually penalizing integrators who use, for example, a dual-core processor and 512MB of RAM as opposed to 1GB. Suddenly, since their computer no longer meets the requirements for Category B, and they no longer qualify for EnergyStar certification in Category A, despite actually having saved a few watts by removing memory.)

Yes, the new spec is better than the old one, but without close attention by consumers, it’s potentially quite misleading. An Energy Star tag does not automatically signify the most efficient PC; only the most efficient one in its class. Are consumers so clear on these class distinctions? Will the Energy Star program make consumers aware?

The EPA’s position is that they’ve had a user friendly one-logo policy since the start, and that’s not changing. Their aim is to identify the energy efficient products in each category, because their perception is that features and functionality drive computer purchases; a consumer looking at a gaming PC won’t compare it to a standard desktop. Hence, an Energy Star logo on an energy guzzler identifies it as the less guzzly of the energy guzzlers — never mind that it still consumes more energy than most other computers without the Energy Star logo in other classes of PCs. We’re told it is an imperfect, transitional system that will be improved.

As to the possibility of a consumer saying, "Well, this gaming PC is an Energy Star, so not only is it more powerful than that ordinary desktop, it’s also more energy efficient"… the EPA says it’s always up to the consumer to do their due diligence, to research what the Energy Star spec means in this case. The details of each ES qualifying computer will be posted in a central database, much like monitors here:

Another possible problem is found in the third-party testing
requirements, or lack thereof. All licensees are required to test their own
products, and submit the results to the EPA. While this reduces
the agencies’ workloads significantly, it also creates some potential for misreporting, accidental or otherwise. The same procedure applies for all Energy Star product categories.


The next step for the program is still unclear. Everything described above is
part of the “Tier one” specifications. Tier 2, which comes into effect on
January 1, 2009, is still a completely unknown quantity. There are a few
interesting items on the agenda: creating standards for servers, blade units and
handhelds, revising the idle numbers and category definitions to reflect changes
in hardware requirements, and so on, but nothing concrete.

It’s safe to say that power efficiency in computing is on the rise, even without EnergyStar 4.0:

  • CPU makers have their power needs under
    control, and we are unlikely to see any more mainstream 130W beasts for the desktop.
  • “Performance-per-Watt”
    is the latest and greatest buzzword.
  • Notebooks, which are far more efficient than desktops, have been
    outselling desktops for a year and the trend continues.
  • Power supply efficiency is
    creeping steadily upwards.

EnergyStar 4.0, while far from perfect, is a step
in the right direction in encouraging more energy efficient PCs and more energy conscious decision making among computer consumers. Let’s hope that the current diffusion of the spec’s original intent can be sharpened in the future.

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SPCR Articles of Related Interest

A New Energy Star… in 2007
The State of the Industry,
March 2006: Through Silent Eyes

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