The author of today's post, Sheryl Canter, is an Online Writer and Editorial Manager at Environmental Defense.

They say knowledge is power. That's the idea behind an interesting innovation in the U.K. called "smart meters" which tell people in real time how much energy their appliances are using, and how much carbon is being emitted as a result. The goal is to change usage patterns by giving immediate feedback.

Energy usage feedback devices are starting to appear in the U.S., as well.

The "Kill A Watt" meter can tell you how much energy each of your appliances is drawing. You plug the appliance into the Kill A Watt, then plug the Kill A Watt into the wall.

Another device, called the Orb, changes color depending on the current price of electricity, thus encouraging people to use energy at off-peak times when it's cheaper.

It's hard to manage something that you can't see. Smart meters, by making the invisible visible, allow people to make smart choices about the appliances they use, how they use them, and when they use them. The lower your energy usage, the lower your carbon footprint.