Like to get more bang for your sustainability-boosting buck? Here's how.

Manufacturers, retailers, governments and other buyers are under a lot of pressure these days to preferentially purchase products with relatively low environmental footprints. But options can be overwhelming: Is it better to favor suppliers who use renewable electricity to produce their products, or those that use recycled cardboard for the boxes that contain them? Until now there has been no easy way to answer that, since measuring the impact of green products can be costly and comparing the re