Seth Godin wrote a post this weekend on marketing green products. He started with a few words on a marketing campaign from Tumi Luggage:

The initial public activities surrounding this campaign start in Spring 2008, with the launch of Tumi's new generation of classic travel and business accessories, the Alpha Collection. Tumi is sponsoring a "Go Green, Get Green" program that rewards consumers with Tumi $100 Gift Certificates for qualifying purchases and where Tumi has pledged to plant 100,000 trees in various reforestation projects administered and overseen by the long-standing leader in the field, Global ReLeaf.

I'm in agreement with Seth: 100,000 trees for buying suitcases? How many trees per bag? Half a tree for a handbag? What's the real number here?

Numbers are Seth's point: Marketing is all about telling buyers why your product is better — which is often easiest if you can just compare simple numbers. I drive a Prius because it gets 50 miles per gallon, which is a clear numerical advantage over my old 20-miles-to-a-gallon Buick.

Even with companies adding labels like "cleantech," "green" or "sustainable" to their products, their marketing efforts will go better if buyers can spot a numerical advantage:

• the distance a piece of produce has traveled
• the amount of space a recyclable won't be taking up in the landfill
• the cost of the energy an energy-efficient appliance is saving

One organization that I think is doing this right is EnergyStar. Consider its efforts to encourage consumers to use compact fluorescent light bulbs: The Energy Star website points out that CFLs last 10 times longer than the average incandescent bulb and saves about $30 over the course of a bulb's lifetime. There's a clear financial advantage, evident by looking at the numbers. But very few companies focus on the numbers when trying to sell green products. Instead, the focus seems to be a nebulous feel-good concept that comes with buying something that helps Mother Earth — a sort of environmental altruism that only targets a fraction of potential consumers.

Seth made one final point that really highlights the opportunities in green businesses today:

People notice a number, and they work to improve it. If every car sold in our country had a real-time gas consumption meter on the dashboard and the rear window, things would change very fast.

Whether a company is making kitchen appliances more efficient, or a company is working to eliminate trash in landfills, there are very real numbers at stake — numbers that everyone, no matter their interest in a sustainable lifestyle, has some level of interest in seeing.