Green Computing is More Than Sleep Mode

By: Juliet Kemp
Monday, October 12, 2009 10:37:20 AM EST
URL: http://www.linuxplanet.com/linuxplanet/reports/6871/1/

Your Real Ecological Footprint

Carbon footprint and sustainability is increasingly important for all of us -- so how does the ecological footprint of your computing habits pan out?

The simplest thing you can do is to make sure that your desktop or laptop goes into sleep or standby mode when it's not in use. First up, make sure that you're not using a screensaver, or there will be little or no energy consumption difference between idle and in use. Next, KDE and Gnome both have menu items where you can set power preferences; or you can of course set things manually with various XF86 options, hdparm, and so on.

Next, consider whether you really need to leave your machine running overnight. If you run cronjobs overnight, try changing the timing to another lull time; or replace cron with anacron. You can also set up automatic shutdown if you tend to forget to turn the box off (I do). Both power management changes and overnight powerdown aren't just the green option, they're also the cheaper option: reduce your power bill!

Which machine?

So, assuming you're already running your existing machine(s) efficiently, what's the best type of machine to keep your eco-tech-footprint low? The figures show that laptops always come out ahead of desktops on power usage. However, it's not just about energy usage whilst in operation: there are other factors to consider, which are discussed in the next section. Netbooks can use even less power (2.5W for some recent chips; up to 10W for others) – but if you use your netbook with an external monitor you'll significantly increase this (an LCD monitor uses about 35W).

More generally, you can check out recent guides to buying energy efficient computers. Look for Energy Star rating, although be aware that this is a hardware standard; for it to actually have an effect you need to make sure your software is firing it up, which means setting the power management options as discussed at the start of this article. You can also use EPEAT, which rates laptops and desktops as Bronze, Silver, and Gold, to help you make your decision if you're buying.

When to replace?

So, should you dash out to replace your aging laptop with a lovely new ultra-low-energy machine? I've certainly seen it claimed that given the steady increases in power efficiency, it's financially worthwhile (in terms of energy consumption) to replace machines every 2-3 years.

The problem is, power usage isn't the only environmental issue associated with new computers. There's also the energy cost, and perhaps even more importantly, the resource cost, of producing a new machine. The EPEAT standard covers some of this when assessing the environmental performance of a machine, but the bottom line is: making new kit has an environmental cost.

There's also an end-of-life environmental cost to old machines. In Europe we now have the Waste Electrical and Electronic Equipment Directive, which makes manufacturers responsible for the environmentally-friendly disposal of their equipment at the end of its life. (As yet there's nothing similar in the US.) This may or may not be part of the reason why manufacturers have begun to develop more recyclable PCs! But even if consideration is given to recycling or non-landfill disposal, that too may have a human cost. (I note in passing that even if a machine is surplus to your requirements it may be useful to someone else: try to freecycle or donate to charity before you throw it out!)

This also brings up the lifespan issue. As discussed above, laptops use less energy in use, but they also tend to have shorter lifespans.

Production and Disposal Costs

If all you're considering is power, we can plug in some numbers. With these power usage figures, an average figure for a desktop in use is around 120W; for a laptop it's around 35W. Assuming the same usage of both machines, and the same power-saving setup (although note that in fact the desktops are also a bit less efficient when sleeping), your laptop can have a lifespan up to 3.4 times less and still come out ahead. So a laptop lasting 3 years would beat out a desktop lasting just over 10 years, on power usage alone. However, a typical LCD monitor uses 35W, so if you're using your laptop with an external screen all the time, that figure goes down to 1.7 (so a laptop lasting upwards of 3 years would beat out only a desktop lasting less than 5 years).

But power usage isn't all there is: there are those production and disposal costs, for which lifespan really does matter. For example, here's an analysis of the environmental production costs for a Macbook. With a laptop, you also have the issue of the cost of the battery and its lifespan: how many recharge cycles are you going to get per battery? Laptops also tend to be less fixable if something goes wrong than desktops (thus further shortening their lifespan). Unfortunately, it's hard to get solid figures on much of this, and in practice of course, other issues (such as portability) may be of more immediate importance when deciding what type of machine to get.

Software issues

When you consider start-of-life and end-of-life costs, it becomes clear that it's better to squeeze as much as you can out of the hardware for as long as possible than it is to replace early to take advantage of energy usage improvements.

But how long is "as long as possible"? When does "end of life" actually apply? When your machine actually stops working altogether; or when it becomes irritating to use?

One drive for more frequent hardware upgrades is that coders tend to write with the assumption that they can use as much CPU as they like; and to write for the often high-powered machines that they themselves may be using. Until recently (when the motherboard went bang) I was still regularly using an 8-yr-old PC: but running a modern Java app on it was an exercise in frustration. Isn't it time to focus more on efficiency of code? My laptop is a Mac, and I was ecstatic to find out that the new Snow Leopard release apparently has a focus on getting more speed, and apparent speed, out of the existing hardware.

If it becomes more common for users and companies to make the effort to keep their existing kit in operation, can we push coders into allowing for this, and thus putting their energies into writing more efficient code? You can argue that netbooks are a useful part of this drive: they operate on the assumption that most of us don't really need massive computing power. As more people place themselves at this hardware point, we could (I hope) see less of the assumption that all users have high-end machines available. Which will increase effective hardware lifespans – and may even cut power bills by requiring less heavy CPU work. It's something to start working towards as we try to tread more lightly on the planet.