Hey Mr. Green,

What's better for the environment, shopping at a store or online?

—Cynthia in Ventura, California

This is a pretty tough question because there are so many variable factors. One study found that online shopping consumed an average of 30 percent less energy than traditional, brick-and-mortar shopping. That’s mainly because people drive to stores to purchase products. But the number-crunchers of that study also conceded that there was significant uncertainty and variability in their analysis, especially regarding transport to the retail store (fuel economy, trip length, purchases per trip, etc.).

Another study contends that shopping online has a greater impact on the environment, when considering the following factors: 

• Many people do not drive alone, but go shopping with others, hence total purchases average more than four items per trip, thereby reducing miles driven per item.

• Shoppers often engage in other activities while at the mall, so miles traveled can’t be assigned only to shopping.

• A lot more goods purchased online get returned, which requires repackaging and shipping (33 percent compared with just 7 percent from stores).

• Online products often require a whole lot more packaging. You can also simply bike or walk to the store, or drive a very efficient car, any of which beats online shopping in terms of environmental impact.

To counter some of these problems, online advocates recommend that consumers

• Do not ask for same-day or next-day shipping.

• Purchase more than one item at a time.

• Ask for eco-friendly packaging.

• Avoid impulsive spending by asking yourself, “Do I really need this?” every time before you click “add to cart.”