National Geographic Society

Here at National Geographic's D.C. headquarters, our cafeteria is big on composting: There's even a photo of a landfill on the trash can to guilt you into throwing that paper cup into the right receptacle.

Pretty soon, if you live in San Francisco, you won't have a choice. On June 23, mayor Gavin Newsom signed the first mandatory composting law in the United States for consumers and businesses.

The law, which goes into effect October 21, is in fitting with the mayor's "lofty green goal" -- zero waste by 2020, he said in a statement.

The city already keeps 72 percent of recyclable material out of the landfill, and turns about 400 tons of leftover food into nutritious organic compost, dubbed "black gold."

The fertile stuff is quickly snapped up by farms and vineyards in the Bay Area, Newsom added.

Composting not only keeps landfills down, the practice also prevents the powerful greenhouse gas methane from being released. That's because bacteria that break down food waste in landfills create a lot of methane as a byproduct.

If you compost food, on the other hand, you return carbon to the soil and encourage plant growth at the same time.

Not to mention compost can work wonders for your lawn, especially commercially made compost, which has high levels of naturally occurring phosphorous and nitrogen that is released gradually and is absorbed more easily by plants. (See our fertilizer buying guide.)

So we get it -- composting is cool, not only because it doesn't heat up a warming planet -- but how do you dig in? First decide if you want to set up shop indoors or in your backyard. If indoors, you can either buy a special bin or make one yourself out of a plastic garbage can. A properly managed bin, according to the U.S. Environmental Protection Agency, won't attract pests or smell bad.

If you head outdoors, select a dry, shady spot near a water source for your compost pile or bin, and moisten dry materials as they are added.

The whole rundown on what you need to know can be found on the EPA's composting site.

Newsom said he hopes that composting will "become second nature for Americans, just like sorting bottles and paper."

With up to a $100 price tag for any San Franciscan who fails to compost, that sounds about right.

--Christine Dell'Amore

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Related:

Get the dirt on how to turn your trash into fertilizer treasure.

Try out composting by starting a carbon diet.

Image courtesy Kessner Photography

Here's a breath of fresh air—one of North America's first "living buildings" opened today in at Washington University in St. Louis, Missouri.

The new Living Learning Center, set in the woods at an environmental-research facility on campus, is also in the running to become the first building to meet the Living Building Challenge.

The initiative, sponsored by the Cascadia Region Green Building Council and launched in 2006, is arguably the most extreme green building rating system in the world.

The builders of the 2,900-square-foot (269.4-square-meter) learning center say it meets the 16 requirements to earn living-building status.

Among the requirements:

--Solar energy will run the building, and any excess will be pumped back into the electric grid to be resold by the electric company.

--Rainwater will be captured and stored in a 3,000-gallon (11,356-liter) underground cistern and purified for drinking water. (Find out how rainwater harvesting works.)

--Porous pavement around the building will absorb storm-water runoff, and no wastewater will be produced.

--Fallen trees or trees slated for removal from nearby woods were used to build the center, meeting the requirement that materials come from within 500 miles (805 kilometers) to cut down on carbon dioxide emissions.

(Learn how to build your own eco-friendly house from the ground up.)

Likewise, the center will be a learning hub for a summer high school outreach program and university classes.

More than 60 project teams throughout North America have signed up to pursue living-building certification, Eden Brukman, regional director of the Cascadia building council, said in a statement.

Washington University's learning center is one of two of the first projects opening in May, but to meet the standards it must be operational for at least 12 consecutive months, Brukman said.

" … There are many people throughout the country—and the continent—watching with eager anticipation," she said.

Visit these sites for more information on green buildings and construction:

How to Get a Green Roof for Dirt Cheap

Whole House Quiz: Learn Where You're Losing Money

Video: Watch a Green Home Makeover

And check out National Geographic's Summer Green Guide for more information on how to green your home and your life.

--Christine Dell'Amore, National Geographic News environment editor

Photo courtesy Joe Angeles/WUSTL

Your taxes are in. And if you're expecting a refund, using it to buy an energy meter could be the best investment you make this year.

Just like financial planning, energy conservation is made a whole lot easier when you have a baseline to work from and know what you're spending.

At a "Town Hall" meeting in March, President Barack Obama once again noted the importance of metering. While he was talking about smart meters, which will be able to help you tap into the new national smart grid we're all dreaming of, there's no reason we shouldn't ask our new administration for metering options in the meantime.

Energy and education experts have said metering provides easy-to-use, practical information that often serves as the impetus for behavior change. By some estimates, meters can result in savings up to 15 percent almost immediately.

If you can plug your air-conditioning unit into a $25 meter and discover within seconds your A/C is eating up unnecessary amounts of energy--and your bank account--you may be inspired to brave a degree or two, or completely unplug.

Other governments, such as the U.K.'s, are already ahead of the curve, providing meters for households. The U.K.'s meter program is part of the country's goal to reduce carbon dioxide (CO2) emissions 60 percent by 2050.

If you can't wait for the administration, head to Home Depot, or set up an Internet-based home energy monitoring system. Google's PowerMeter--an online dashboard to help you gauge energy use and decide where to cut--is expected on the market soon.

Read Green Guide's tips for carbon dieting.

Learn more about energy conservation strategies in the March issue of National Geographic magazine.

Test, or meter, your energy-saving smarts.

Read about alternative energy options.

--Tasha Eichenseher