• Competition between organic food markets is escalating, driven by consumers' desire to eat healthy.

• Late last year, a bicycle courier began ferrying parcels between businesses in downtown Louisville. It was the first courier service in the city to offer an alternative to motorized carriers.

• Green architecture is making inroads in the building industry.

Statistics suggest that these Louisville ventures are chasing an emerging market.

Sales of organic food and beverages increased between 20 percent and 24 percent during the 1990s, according to the Organic Trade Association. Sales for 2003 are expected to top $13 billion, up from less than $2 billion a decade ago.

In Kentucky, the number of fleet vehicles running on alternative fuels has doubled to about 3,000 over the past five years, according to the Kentucky Clean Fuels Coalition.

Still, most cars are powered by gasoline. And more than 90 percent of the dry-cleaning industry still uses the popular but controversial perchloroethylene rather than alternative solvents.

So the question remains: Is green viable?

For Rob Auerbach, it is. An entrepreneur who helped establish organic food in Louisville a generation ago, Auerbach has expanded Rainbow Blossom Natural Food Markets into three Kentucky stores with 85 employees.

The market for natural foods has matured since Rainbow Blossom started as a restaurant and caterer in 1977. The U.S. Department of Agriculture reported last year that more than 20,000 natural-foods stores stock organic products, as do nearly three-fourths of traditional grocery stores.

But the market that Auerbach helped build is changing. Wild Oats, a national retailer of natural foods, has opened a megastore in Louisville. Whole Foods Market plans to open a 22,000-square-foot store next January.

Auerbach said anyone can sell organic, but not everyone knows organic. He counts on employees' expertise to build customer loyalty.

A green business might appeal to die-hard environmentalists. But to succeed, it must reach everyday consumers.

Jackie Green is aware of that delicate balance. Green, an avid cyclist and head of the Coalition for the Advancement of Regional Transportation, launched CBD Courier Service, a bike courier service, in October.

"We're experiencing slow but steady growth," he said. "Each week is better than the week before."

Green said some clients use the service for environmental reasons. "But then others want to know how much it costs, and they will make their decision on how much it costs and based on the service."

Louisville architect Mark Isaacs said home buyers are increasingly interested in more energy-efficient houses.

"That's immediately something that's appealing to them, particularly with the large price increases in natural gas that we've had here over the past two or three years," he said.

But the trend extends into commercial construction. Isaacs incorporated green design features into the Roth Family Center for Jewish Family and Vocational Service.

The building's longest and tallest side faces southeast, allowing it to absorb direct sunlight in winter. Overhangs block direct sunlight in summertime.