Low Energy Computing

Energy costs are important to almost everyone. Not just for the cash cost, but increasingly in terms of the link to environmental harm. Looked at from that angle, the computer industry is headed in the wrong direction with desktop PCs consuming more and more power as the software demands faster processors and more memory. We've measured desktop power consumption in the range of 70-100 watts per PC. Including the monitor 150 watts is common. On a typical site with, say, 400 desktops, it amounts to 60KW. At 8 hours a day, 5 days a week assuming 10p per unit, that's £240 per week. Even in schools which only run a 35-week year, the total is close-on £8,400 a year just for the desktops. All that heat has to go somewhere, requiring investment, running costs (more power) and maintenance for air-conditioning plant too. Businesses and charities are paying even more, not having the long shut-downs that schools do. And how many places do you know where the PCs are left running all the time, not only 8 hours a day?

Some of the schools we have spoken to are under pressure to get their PC/pupil ratio higher but are unable to because there isn't the electrical capacity on the site or in the buildings. For them the power consumption is a severe constraint on what they do.

The move towards thin clients is a big help in reducing energy consumption. Depending on the technology used power consumption can be as low as a few watts per device (the SunRay 2FS is quoted at a typical power consumption of 7.86 Watts). They also require considerably less energy in the manufacturing process, but that's less of a concern for most users with bills to pay.

A further reduction in power consumption can often be found by switching from CRT monitors (the bulky box-shaped monitors) to LCD flat panels. This is highly dependent on the particular products in question with LCD makers not apparently designing for lower power consumption yet. Typical measurements that we have seen are around 90W for an old-style CRT monitor with 35-50W for the corresponding LCD.

A thin-client environment requires powerful servers to run the applications behind the scenes. These do need air-conditioned rooms but we find that each typically consumes under 400 watts and will serve around 30 thin clients with good performance. Server manufacturers have woken up to the concerns of users now and are increasingly focusing on producing servers that are power-efficient and which reduce their consumption when they are not being used. Whilst more could be done about that it's an encouraging trend.

Low-energy issues alone may not be compelling reason to choose to go down the thin-client route. However, it's certainly a benefit and one that may be of increasing value in the years to come.