by Tony Sirna
Biking for the Blogathon

Biking for the Blogathon

For today’s blogathon-fundraiser we are trying to power our computer via pedal power but pedaling is certainly not the answer to all of our energy needs. America’s electricity use per capita is over 35 kilowatt-hours per day. If you wanted to supply all that energy via pedal power, each person would need to bike at full speed for 118 hours per day. In other words it would take the entire population of the US and China pedaling 24/7 to generate enough electricity for the current US demands. Or…

Conservation is almost always a key element to meeting our needs in a sustainable way. Before we look at alternative power or fuels it is best to look at reducing our demands. Once we are consuming less, sustainable sources of power are a lot more realistic.

How you can reduce your computer’s power consumption

Your average desktop computer uses between 150 and 300 watts while it is running. Your first step in conserving energy is to turn off your computer when you are not using it or at least make sure that its power management settings are configured to have it sleep or hibernate when it is not in use. It used to be that people worried about wearing out disk drives from turning computers on and off, but that is not really an issue any longer, given modern drive technology and the typical lifespan of a computer these days. This is the most important thing you can do to save power – make sure your computer is sleeping or off when you are not using it.

The next thing you can do is consider switching to a laptop computer. Laptops can easily use only 10-33% of the power that a comparable desktop computer uses. To make them last longer on battery power they are designed with low power components.

Another option is to switch to an Energy Star computer, either desktop of laptop. To get an Energy Star rating, computers have to automatically shut down when not in use and are generally designed to have low power draws. The trick is you have to make sure that you don’t turn off any of the power saving features, like the power management system.

So lets look at an example. Let’s say you’re currently using some random desktop with an external LCD monitor (heaven forbid you still have a CRT monitor). Let’s assume it uses 150 watts and you leave it on 24 hours a day – you’ll use 3600 watt-hours per day. If you let it go into sleep mode (which use something like 5 watts) for 16 hours a day you cut your use down to 1280 watt-hours. Now let’s say you switch to an Energy Star Desktop like the iMac 21.5 inch which only uses 90.5 watts while running and 2 watts while sleeping, your power use could drop to 756 watt-hours per day.

Laptops! - Blog Central at the DR Blogathon

Blog Central at the DR Blogathon

If instead you get a new MacBook Pro with a 13 inch display which Apple says uses 14 watts while its running with the display on. Let’s say you use your computer for 8 hours a day on average and the rest of the time you leave it in sleep mode (which uses 1.1 watts), you’re using about 130 watts per day for your computing needs. At that point your computer is using about the same energy as a lightbulb (a CFL of course, heaven help us if you’re still using incandescents).

So to summarize:

  • Desktop (24 hours on)- 3600 watt-hours/day
  • Desktop (8 hours on) – 1280 watt-hours/day
  • Energy Star Desktop (8 hours on) – 756 watt-hours/day
  • Energy Star Laptop (8 hours on) – 130 watt-hours/day

The electricity you use running your computer is only half the story

Now one thing to consider is that the electricity you use running your computer is only half the story. Apple gives a detailed assessment of the greenhouse gas impact for each of its products and “customer use” generally accounts for about half of the emissions. So it also helps if you buy used, or keep your computer for longer.

How Does Computer Use Compare to Other Eco Impacts

So how do home/work computers fit into the big picture of your ecological footprint?

On average Amercians emit about 24,000 kg of CO2 equivalent (CO2e) per person per year.

Using Apple’s figures for its products, computer use, including the embodied energy, produces about 100 kg to 300 kg per year per computer. Compare this to over 1100kg for a desktop thats on 24/7, or 465kg for the desktop on 8 hours a day. By changing your computer use, you could save up to 1000 kg of CO2e or about 4% of the average American’s annual greenhouse gas emissions.

What else can you do that saves 1000kg of CO2e?

  • Drive about 20% fewer miles (around 2200 miles)
  • Increasing your MPG by 25%
  • Eat 200 fewer cheeseburgers
  • Take 1 less 2500 mile round trip airplane flight

These aren’t examples of total lifestyle changes but they aren’t insignificant either. And I would certainly rather use my share of CO2e to take a vacation rather than leaving my computer running 24/7.

Can computing be part of a sustainable world?

There are a lot of factors involved in that question, but my gut sense is that it can be, assuming we are making sustainable choices in the rest of our lives. If we were aiming for reducing our impact by 90%, then using a laptop for 8 hours a day might be about 5% of our reduced impact. Still significant, but for those of us who are so dependent on our computers as to practically be cyborgs, I think its worth it.

Of course this was all about your home computer, coming next, What is the impact of the internet!

Consider making a donation to Dancing Rabbit Ecovillage as part of our blogathon. All donations will be matched dollar for dollar, doubling your impact. Thanks!

6 Responses to “How You Can Reduce Your Computer’s Electricity Use to a Sustainable Level”

  1. [...] might consider this guest post on keeping computer energy use down by Tony Sirna a bit ironic, as we’re all sitting around a [...]

  2. “heaven forbid you still have a CRT monitor” – um, yes, my CRT is still working so I’m still using it. I happen to think it would be environmentally irresponsible to dispose of it to buy something new. And my computer has had a new disk drive, added memory, and even new capacitors on the motherboard in order to avoid replacing it.

    I like the detail in your post, but the confusion as to environmental effects comes when we begin to consider the life-cycle of a product. Can I save enough energy to make it worthwhile disposing of something and buying a newer, more energy-efficient replacement, whether it be a car, a computer, a dishwasher, or a 95% efficient furnace?

  3. [...] separate home computer impact and the impact of servers and internet infrastructure. See my post on reducing your computer’s eco impact for more on the [...]

  4. Hi Alison,

    It can be tricky to know when to dispose of an older but functioning object and get a new, more efficient one. I love making things last a long time, mending clothes, fixing computers, etc.

    There are some things though, where the math makes it pretty clear that it is better to replace than continue using. Such things include:

    – Incandescent lightbulbs
    – Refrigerators from the 1960s
    – CRT Monitors
    – Old cars that get 15 mpg
    – etc.

    A quick google found this tidbit:

    Each LCD monitor that replaces a CRT monitor saves the University about 344 kWh of electricity ($30.96), or 104 kg of carbon dioxide emissions, per year (

    Thats the equivalent of burning 11 gallons of gas.

    I don’t think it takes that much energy to create a new LCD monitor. I think it is best for the environment to recycle your CRT and get an efficient LCD or laptop.

  5. Another idea: instead of buying used, try looking for an organization in your town like Free Geek … (portland, or) (columbus, oh)

    Volunteers rebuild old computers and laptops, install a copy of Ubuntu Linux, and then give them away for free after one has attended several workshops and classes on basic computer maintenance, etc.

  6. [...] lot of money and what happens when you run out of energy? Another thing you can do is considering switching to a laptop. Laptops use only 10-33% of the power that a desktop computer uses. They are designed with low [...]

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