If you live in Boulder or Denver, Colorado, you can now check a Kill-A-Watt power meter out of the public library and monitor your energy consumption at home.

In a program sponsored by Xcel energy, the libraries have a stock of power meters that any library card-carrying member can check out for three weeks at a time. If you're new to the practice of home energy monitoring, it's simple: plug the Kill-A-Watt meter into an outlet, and then plug an appliance (fridge, phone charger, etc.) into the meter, which can measure either the instant energy increase, or the average rate of energy use over time.

And, says Big Green Boulderp, "the meter tells you how much your devices pull off the grid—even when they're not on." (An energy suck that really adds up.)

Demand has been overwhelming since the program began: the waiting list for Denver's 49 meters is 300 people long, and the program is expected to be just as popular in Boulder, where the program is newer.

Understanding your energy consumption is the first step to knowing how to reduce it. So if you're in Denver or Boulder, get to the library and check out a Kill-A-Watt. If you're not, get to the library anyway and suggest your own town start up a similar program.

Either way, check out some books while you're there, if you remember how that works. Your public library has a lot to offer.