Google has revealed a new free online tool called Google Powermeter that allows you to monitor your home energy usage and greenhouse gas emissions online via your computer or mobile phone. The energy usage service uses smart meters or an add-on clip for conventional meters.

Monitoring energy usage promises to help consumers save 3-15% annually on their utility bills, which frankly doesn't add up to much. The annual savings for homes in the UK would be £75 per year.

The app is free from Google but the AlertMe Energy device required is £69 or £3 monthly. There goes your first year of savings. I wonder how you install the device and if you have to get the electric company out to do it.