GreenSpace: E-tail or retail kinder to Earth? They did the math

By the time the fourth Harry Potter came along, the boy wizard was getting a massive carbon footprint.

Never mind all the paper.

As Scott Matthews took in all the hoopla about the 9,000 delivery vehicles FedEx was deploying to deliver all the copies ordered from Amazon.com - more than 250,000 - he was taken aback.

"That was an awful lot of stuff to put together for the convenience of not having to go to the store," he recalled.

Matthews, a professor of civil and environmental engineering at Carnegie Mellon University in Pittsburgh, began to wonder: Which was more environmentally friendly, ordering the book online or going to a store?

Retail? Or e-tail?

That was in 2000. A few years passed (during which FedEx delivered 400,000 copies of the next Harry Potter in 2003), and the online retailer, buy.com, wound up joining the university's Green Design Institute.

Better still, the company was willing to hand over data.

So Matthews and colleague Chris Weber went back to work on the old question.

They decided to look at the cost - both in energy consumed and carbon dioxide emitted - of getting a flashdrive from where it was manufactured to a home, comparing buy.com with a customer driving to store.

For each method, transportation of the flashdrive was the major factor, the least efficient step in the chain of events.

For customer pickup, it was the distance from home to store. For e-commerce, it was the distance the delivery truck drove, the killer being the so-called last mile to customer homes.

But there was plenty else to consider. The group that Matthews and Weber led looked at energy use in the warehouse and the data center that took the online orders, factoring in meter readings for three years.

They looked at packaging.

They factored in the energy intensity of big trucks, medium trucks, airplanes.

Their data on consumers and retail stores were less precise, but based on various national studies, surveys and estimates, they factored in energy use in retail stores, consumer driving and buying patterns, and energy use of home computers (presumably the main e-ordering tool).

They wound up with a complicated 18-page report.

And the winner is . . . e-tail.

They concluded that within the buy.com model (it has no warehouses), e-tail is about 30 percent greener than retail on both counts: energy and CO2.

Further, within the online world, ground deliveries are far better than express deliveries that involve airplanes.

(In case you're getting suspicious about now, buy.com, as a member of the university's Green Design Institute, donated money to a broad research fund, but did not fund this study per se.)

But hold on before you dash to the keyboard. The authors acknowledge this is just a beginning. There's some uncertainty - and a potential for wide variation - in some of the parameters.

And there's considerable variability among individuals. As Matthews notes, "Nobody's average. It's sort of like Lake Wobegon. Everybody's above average."

So this isn't an ironclad dictum. I view it more as information to factor in, measuring my circumstances against their statistical average: someone who drives 7.5 miles to a store in a car that gets 22.5 miles per gallon and picks up one or two items.

So if I'm in my Prius and I'm only going to detour a mile out of my way to stop at King of Prussia Mall on my way home, I'm good to go.

But not long ago I considered driving to a York County nursery to get a special dwarf fig tree for my edible landscaping plan. Scratch that. I'll order online instead.

Meanwhile, there's one more variable. The researchers concluded the best way to make either system more efficient was simply to buy more.

The economy could sure use the love right about now.