At American University in Washington, D.C., there are three rules of sustainable purchasing:

• 1. Don't buy what you don't need;
• 2. Use what you have;
• 3. When you do need to buy, make it greener.

Let's look at how these approaches have saved time, money and the earth's limited natural resources.

Dude, where's my tray?

In April 2009, a group of students enrolled in the Seminar in Environmental Issues conducted an experiment in the Terrace Dining Room, the university's main dining hall that serves more than 650,000 meals a year. The students removed serving trays from the dining hall for half of the meals during a two-week period and measured the amount of post-meal food waste and number of bowls and plates used for every meal. They discovered that food waste and dish use were dramatically lower when trays were removed. Meals served without trays resulted in 32 percent less food waste and 27 percent fewer dishes used.

Based on these results, the university administration decided to go trayless. Bon Appetit, the university's contracted food service company, was more than happy to cooperate, since it amounted to significant savings on food costs and reduced costs associated with buying and cleaning trays and dishes - less labor, less water, less energy and fewer dish replacements.

In the fall of 2010, the Office of Sustainability worked with Bon Appetit to track food purchasing according to sustainability criteria. For three months, all food purchases were tracked for distance of transportation from production to consumption, as well as categorized based on various sustainable certification standards: Fair Trade, USDA Organic, Marine Stewardship Council, Food Alliance, Rainforest Alliance and Protected Harvest. Using the U.S. Green Building Council's LEED green building guidelines, 25 percent of food purchases were considered sustainable. Based on the Association for Advancement of Sustainability in Higher Education's STARS sustainability system, 36 percent of food purchases were considered sustainable.

Does trayless dining demonstrate the three rules? Rule 1: Trays are unnecessary, so we stopped buying them.

Rule 2: Now we are eating the food we buy instead of burying it in a landfill.

Rule 3: We are buying better, fresher food that is local, organic and sustainable.

A mother lode of motherboards

In 2010, American University learned that its contracted electronic waste recycler had been caught exposing prison laborers to hazardous substances. Therefore, a new e-waste recycler contract was negotiated. The deal looked good for both sides - the recycler would get enough useful electronics that their value would underwrite the cost of recycling equipment that was no longer useful. The university essentially saw this as a free recycling service. In reality, valuable equipment was being given away that could have been reused on campus.

The university Office of Sustainability, eager to ensure that old electronic equipment was being properly diverted to recycling, convened a group to develop processes for collecting e-waste. An unexpected result of this group was development of a better process to track the university's inventory of computers. Before a computer could be routed to recycling, the Office of Information Technology would now assess the equipment and determine whether it could be reused internally.

After the new processes had been in place for a year, the e-waste recycler began charging the university recycling fees "because," they said, "you guys aren't giving us any useful equipment."

Is this a case of too much success or a hidden cost being avoided? The university is now paying a few thousand dollars for recycling of a full shipping container of e-waste. But this cost is easily offset by using just a handful of the recaptured computers that would otherwise be given away for almost nothing.

At the same time, an inventory of computer purchases sought to determine how many were registered in the Electronic Products Environmental Assessment Tool (EPEAT). To our happy surprise, we learned that all of the university's standard new computers were already EPEAT registered models, 82 percent attaining EPEAT Gold and 18 percent earning the EPEAT Silver rating.