How to Calculate Your Carbon Footprint

Engines idling in traffic jams wasted an estimated 2.3 billion gallons of fuel in 2003, according to the Texas Transportation Institutes's 2005 Urban Mobility Study.

Related Story: Ten Ways to Drive Green >

Maybe you are driving less or looking for a more fuel-efficient vehicle. Or maybe you are just being more conscious of how to squeeze extra miles per gallon from each tank of gas — regularly checking tire pressure, turning off the air conditioner, or doing other things to save fuel. (See a list of tips for driving green here).

Maybe you are unplugging seldom-used appliances in your home or choosing to buy more energy-efficient ones. Certainly a lot of other people have. More than 1.5 billion consumers have chosen Energy Star-qualifying products since the label was introduced in 1992.

That is understandably so, too. A refrigerator designated with an Energy Star label — considered a stamp of approval for its efficiency — can reduce the monthly household electric bill by 15 percent, according to the U.S. Department of Energy.

But the most comprehensive way to reduce environmental damage might be to figure out exactly how much of it is your personal responsibility and take steps to shrink that amount.

In Depth: 10 Luxurious Ways To Cut Your Carbon Footprint

Author Alexandra Shimo-Barry knows how. In her new book, "The Environment Equation," Shimo-Barry, a reporter for Maclean's in Canada, teaches readers how to calculate their carbon footprint, which is the amount of greenhouse gases in units of carbon dioxide they produce, by using the following formula:

A.) Multiply your monthly electricity bill by 105.

B.) Multiply your monthly gas bill by 105.

C.) Multiply your monthly oil bill by 113 (if you don't use either B or C, enter 0).

D.) Multiply total yearly mileage driven by .79.

E.) Multiply the number of flights 4 hours or less by 1,100.

F.) Multiply the number of flights 4 hours or more by 4,400.

G.) Do you recycle newspaper? If no, add 184. If yes, add 0.

H.) Do you recycle aluminum and tin? If no, add 166. If yes, add 0.

Flying less will reduce your carbon footprint.

A+B+C+D+E+F+G+H = your carbon footprint. A number below 6,000 (reflected in pounds per year) is excellent. Over 22,000? Not so great. Anywhere from 6,000 to 15,999 is good, while 16,000 to 22,000 is average.

If your number is higher than you would like, there's good news: There are hundreds of ways you can shrink your carbon footprint, and many of them aren't as sacrificial as you might expect.

Shimo-Barry says that lack of will, not austere alternatives, is the No. 1 barrier blocking would-be waste-reducers.

"There's still inertia when it comes to making small changes," she says. "But Americans emit 20 tons of carbon dioxide per year. Even if we cut that by a ton — which isn't difficult — it would make a huge difference."

Simple Steps

Eating locally grown food is one of the easiest ways to reduce your footprint. Whether you begin visiting the farmer's market every Saturday to pick up local fruits and vegetables or, if you are able, dining at restaurants serving regional fare, eating locally allows you to eat well without funding the energy used to import food from other regions.

Jason Karas, founder of Cambridge, Mass.-based Carbonrally.com — a gaming Web site that challenges users to reduce personal emissions through online competitions — says that drinking locally microbrewed beer is another way to shrink your footprint, for much the same reasons as eating regional food.

"It's also a great way to support local entrepreneurs," Karas says.

Reducing the amount of electricity you use will save money each month.

Buying second-hand is another way to reduce your footprint. For many, vintage shopping has become as chic as getting on the list for the newest pair of Christian Louboutins. Buying vintage clothing and accessories is about more than looking sharp: These practices will reduce your carbon footprint by eliminating the energy it takes to produce something new. What's more, you might get that Hermes Birkin for $2,000 instead of $8,000. Those not as used to buying second-hand should read "Shopping Tips for Vintage Clothing Collectors" as a how-to guide.

Sustainable wood furnishings are another smart lifestyle alternative. Before you redecorate your home by raiding the Conran Shop, consider buying pieces from eco-friendly shops like Vivavi and Environment Furniture. Both offer stylish, modern goods — like a mid-century-styled credenza or a curvy bamboo rocking chair — that are Forest Stewardship Council-certified, which means they've met 57 earth-friendly criteria established by the organization. The criteria include minimal pesticide use, protection of local wildlife, and unionization for loggers.

In the market for a second home? A penthouse on Central Park South might not sound like the most efficient way to cut carbon, but city living is often friendlier to the environment than suburban life. That's because many urbanites rely on public transportation. And even a two-floor penthouse in the Trump Tower uses far less energy than a sprawling seven-bedroom mansion. What's more, when water, sewage, and electricity are shared, less copper — which is in plumbing and electrical systems and is a major contributor to landfills — is needed.

It's all evidence that living grandly can do the earth well, as long as you know where to cut back.

In Depth: 10 Luxurious Ways To Cut Your Carbon Footprint