Following a previous thread on Planet Debian (allowing for kids delaying projects, as usual), I borrowed a power meter to see what the consumption of various computers and electronics around the house was. An interesting and worthwhile exercise.

Computers

My main gateway system (hosting this blog, mail, etc. on a static IP) is a Pegasos PowerPC; it is on 24 x 7, and pulls approx. 60W. Other computers around the house include a Dell 2.5 GHz P4, which is my main development machine (with multiple disks, etc. onboard) pulling 72W. Downstairs, for family use we have an Intel MacMini pulling approx. 30W. Peripherals add up: on the Pegasos there is an ADSL router and a Linksys Wifi router, pulling approx. 5 W each continuously, and a UPS which consumes around 10W (I'm not sure if this is continuous, or high because its recharging a battery which was drained by pulling power plugs to measure the power usage ...). The LCD monitor upstairs (used by Pegasos and Dell) draws 20W.

If I was purchasing again, I'd get a MacMini for the gateway. The current setup costs, I estimate, 7.50 Euro /month, which is probably worth it to have a 24x7 server (I'm not sure if moving to a hosting facility would be worth it, as it has advantages for running bittorrent, etc. that a remote server wouldn't, as well as being able to host content without the legal threat that a hosted server would have: with the current setup, if anyone challenges the content of stuff on my server, my ISP is not legally involved (as I host it), and hence won't (or shouldn't) pull the plug. This is worth something to me, even if I don't spend my days in court defending libel actions).

One surprise was the CRT monitor used with the MacMini draws 10W when powered off, not on standby. Turn it off at the mains switch rather than the monitor button. Wall warts (chargers, etc.) draw around 1-2W due to eddies when nothing is connected.

Conclusions: Swapping the Pegasos and MacMini are not an option as the family prefer the convenience of the fast start-up OS X. (This has made me think fast booting and suspend-to-disk are good priority goals for Debian.) I might however replace the Pegasos with an old pentium-class laptop, which would, at 25W, drop 40-50W as I would no longer need the UPS for 24x7 use. Put all peripherals, wall warts, etc. on a separate power strip that can be easily turned off together when not in use.

TV

We have a TV with the growing set of set-top-boxes: a DVD Player, Satellite unit and VCR, along with a SCART switch to connect them all together. Between them, they pull 86W. With the TV turned off, the boxes draw 20W. (TV pulls 10W on standby).

I've been looking at getting an "Intelligent" mains lead, which cuts the power to the peripherals when the main item (e.g. the TV) is powered down, either totally or on standby. At nearly 40 Euro, however, it will take over a year to pay for itself. The alternative is just turning them off by hand, but of course as in most houses, the main switch is buried behind the TV cabinet out of reach. I'll swap the power strip with one with a single main switch that can be reached easily at the end of the evening instead.

Other Big Users

The house was designed with energy-efficiency in mind, and theres not much scope for savings elsewhere. The main users are underfloor electric heating, water heating, washing machine and dryer (condensor type). The water heating we hope to replace / augment with Solar over the summer; ditto the drier, with an outdoor shed /gazebo for drying clothes in the rainy Galway days. While the drier consumes a lot of electricity, at least the hot air is recycled via a heat-exchanger to heat the house in winter when its most used.

Its worth keeping an eye on the drier and washing machine, though. We mostly use these at night, using cheaper Night-rate electricity, so while our usage patterns may not change, keep an eye on the energy consumption of these devices: as they grow old the bearings, motor, etc. begin to wear and energy consumption goes up. Look out for when to replace them.

The other big niggle I have is a light fitting in the main living room. This is expensive, with 3 x 60 W spotlight bulbs in it. The kitchen, which is approx. half the size of the living room, gets lit by a single 20 W CFL. Swapping the spotlights with CFLs is not an option, and replacing it means replacing a ceiling mounted fitting: as the wires are embedded in the ceiling, moving it is not trivial. Any recommendations ?