On Oct. 31, the population of Earth reached seven billion. According to the UN, the United States are home to 313 million people. But we use nearly 100 quadrillion British thermal units of energy per year, according to a report by the National Energy Education Development Project. That’s a 100 followed by fifteen zeroes, for the numerically-confused.

A hundred quadrillion, that’s not so bad, right? Compare energy use in the United States to that around the world. The UN estimates the population of Africa as slightly over one billion, and according to NEEDP, Africa uses only 14.5 quadrillion Btu of  energy per year–less than a fifth the amount of our entire country.

NEEDP reports that the per capita annual energy use in Africa is 16 million Btu, while in the United States, that figure is more than twenty times higher. The per capita energy use by Americans every year is 340 million Btu.

This is a dramatic example, but the fact is that people in the United States use a lot of energy.  You can easily reduce the energy you use in a number of ways.

• While the weather stays nice, open your window to air out your room instead of turning on the air conditioner. Just remember that open windows can cause doors to slam in some dorms.
• As it gets colder, let the sun keep your room or apartment warm. Open up your blinds during the day to let in the warmth.
• At night, stay warm with extra blankets instead of a space heater (which aren’t allowed in dorms anyway). Or find someone to cuddle with to heat things up.
• Just because winter is approaching doesn’t mean you can’t keep walking to Harris Teeter, CVS, and El Azteca. Remember gloves and a hat and you might even make it to Pizza Hut without getting cold.
• Turn off your computer, radio, and TV when they are not use. Your neighbors are probably not interested in listening to Cake Boss reruns, and you’ll be doing the planet a favor, too.
• This is an easy one: turn off the lights! Even energy-efficient compact fluorescent and LED bulbs use electricity that can be saved simply by keeping the light off when you’re not at home.

Have a tip for reducing your energy use? Let us know in the comments, on Facebook, or on Twitter!