The concept was born last July, upon the release of Harry Potter and the Goblet of Fire, the fourth book in J.K. Rowling's popular series. The accompanying book-buying frenzy -- crowds of hungry readers storming stores at midnight and millions of people placing orders in advance online -- raised a question.
"We started thinking about the idea of whether using overnight shipping was better or worse for the environment than going to the bookstore and buying it yourself," says H. Scott Matthews, research director of Carnegie Mellon's Green Design Initiative.
The researchers' theory is that the traditional distribution model is more efficient because books are shipped to stores in bulk in big boxes. With electronic commerce, on the other hand, the shipments are broken up and books are packaged in individual boxes to be transported by air and ground by couriers.
"Every time someone ordered a Harry Potter book, it was put in a little box and shipped overnight," Matthews says.
Which delivery is greener?
Their conclusions about which method is more environmentally sound, however, are not so neat. The answer, in short, is that it depends. It depends on how close buyers live to the nearest bookstore, and how far the product must be shipped if the buyer requests home delivery.
"Consumers aren't used to thinking about e-commerce having any environmental impact," Matthews says. "When people buy things online, they're not necessarily thinking about what's happening; it's almost like the item is being teleported from the warehouse to their doorstep. The fact that you aren't going to the bookstore doesn't mean there's no environmental impact. In some cases, it's much worse."
In other cases, though, e-commerce is environmentally better. The Green Design Initiative's study shows that having an online-ordered book shipped creates about 10 per cent fewer greenhouse gas emissions than driving to a local store and buying it. (Ten pounds of gas emissions per book compared with 11 pounds when the buyer shops in brick-and-mortar outlets.) But that only holds true if the product is shipped less than 750 miles.
"If you need a book shipped from [across country], you know it's going to be worse," Matthews says.
Splitting the impact
Also, an e-commerce purchase is worse for the environment if you live fewer than 2 miles from a brick-and-mortar store.
"If you live close to the bookstore, it's better to drive there yourself," Matthews says. Better still, walk. Passenger car trips are notoriously high in greenhouse gas emissions, he notes.
The Green team's study also finds that books ordered online generate two and half times as much packaging material as books bought in stores. Manufacturing those materials is "not exactly a clean industry," Matthews says, and that's "one thing that concerns us."
While the Green team focused the study on books, Matthews says the same conclusions hold for other products, such as CDs. It's not necessarily the same with heavier items such as PCs, where there appears to be no significant difference between e-commerce and traditional buying methods.
Between the more substantial packing material of a shipped product ordered online and the environmental impact of motoring to a computer store, "it basically becomes a wash," he says.