Apparently Microsoft isn’t content battling Google on your monitor screen: it wants to do battle at the mains socket as well.

The firm has launched a beta test of an online application designed to give customized advice on how to save energy in your home. The idea is that users then give feedback on the effects of this advice and the system uses this information to refine its future advice.

The scheme is currently only available by invitation, which you can request via the official site. It’s limited to US citizens for the moment, though there are plans to roll it out in Canada and Western Europe. The system will also be made available to utility firms so that, for example, they can build it into their own sites.

This may sound reminiscent of Google’s recently-launched Power Meter scheme, which is also designed to make home energy saving easier. However, the two systems work in different ways:

Google Power Meter hooks up to the home’s electricity meter (it only works with special ‘smart meters’) and details power consumption on the computer screen. It keeps track of changes in use over time, allowing users to see which devices are sucking up the most juice. However, at the moment, Power Meter is purely an information tool and simply replaces the prohibitively tiresome task of repeatedly going to the meter cupboard and taking readings.

Hohm does not connect to the meter. Instead users either type in details of their power consumption and household set-up, or use averages for their area and home type (which will produce less accurate results). The system is more about giving relevant advice than monitoring power use. There will also be a social networking element with users able to swap tips with other users in their area.

Of course, once you look at the two set-ups, it’s pretty clear the ideal solution is a blend of the two: a system that keeps track of how much power you are using, then tells you how to reduce it. Let’s hope healthy competition between the search giants produces a set-up that achieves that, rather than something which tells you your fridge is a power-hog and bombards you with ads for a replacement model.