Calculating your carbon footprint—the amount of carbon dioxide produced in everyday life —is a fairly simple exercise that many Dwell readers have likely done by using an online calculator; but how many people are measuring the amount of electricity used by all the individual appliances in their homes?

Simply plug in a little device called the Kill-A-Watt and connect it to your appliances to see how much power each uses. Put a number, and dollar amount, to the phantom power drain all our cords draw when not even in use. The device is easy to find and a shockingly inexpensive way to monitor and reduce energy use.