For years, the complaint has been that Pittsburgh misses out on conventions because it lacks a big headquarters hotel of 900 rooms or more.

I thought events of last month would provide the final answer to that longtime beef, with the answer being:

"Hey, we just hosted the G-20 summit, the biggest conference in the world, so I think we can handle your International Society of Dryer-Lint Collectors meeting."

Turns out I'm wrong, though.

"That's not how it works," Joe McGrath, longtime president of VisitPittsburgh, said when I started to run this past him.

Don't get him wrong. The G-20 will be great for Pittsburgh's image. "Image" is a nebulous term, but polling suggests that our less-than-glamorous reputation has cost the city 45 conventions and 157,000 room nights since the convention center opened five years ago, Mr. McGrath said.

An improved image after hosting the world will get the city only so far, however, because handling the delegations of dozens of nations in almost as many hotels is different from most conventions.

Philadelphia has 1,800 rooms attached to its convention center and Indianapolis has 6,000, Mr. McGrath said. People who plan big gatherings like to have everyone under one roof.

He has been arguing for a headquarters hotel since he arrived from the Twin Cities 19 years ago -- but I don't see one coming, not if it's going to take another multimillion-dollar subsidy to get one. The convention center itself is supposed to be a catalyst for tourism, and at some point Pittsburgh needs to stop catalyzing the catalysts. We need to go with the city we have.

What we have is starting to look pretty good. There are now 4,200 hotel rooms within a mile of the convention center, and 3,600 of them are "committable" to any convention, Mr. McGrath said.

The G-20 is not the only indicator that the "green" convention center is paying dividends.

Not long before the convention center opened, VisitPittsburgh did a poll asking whether the center's Earth-friendly features would tip the balance in Pittsburgh's favor for convention planners, if all other factors were equal. Only 2 percent of planners said "green" mattered, Mr. McGrath said.

That jumped to 20 percent three years ago, Mr. McGrath said. And even as late as three years ago, some people still might have thought a "green building" was a reference to the paint, so I'd expect he's right that even more planners would be interested in the center's environmental credentials today.

I confess I have never been a big believer in convention centers providing a huge economic bump. When Heinz Field, PNC Park and this convention center were built, I thought this last investment to have the least certain return.

Only a finite number of cities have professional football or baseball. We know the Steelers will sell out each season and we know that at least 1.5 million people will trek to North America's prettiest ballpark to see the Pirates, even when they stink up the joint. But our convention center competes with an untold number of cities.

If going green provides Pittsburgh an edge, it's one we badly need.

"I wish I could take the credit," Mr. McGrath said. "I just wanted [more] space."

Teresa Heinz, the foundation community and the Green Building Alliance are the reason we have the convention center we do. In 1998, the Heinz Endowments and other foundations sponsored a $783,000 design competition for a new convention center. That led to the selection of New York architect Rafael Vinoly and his sloping-roof design. Its natural ventilation and recyclable water instantly flipped Pittsburgh's old image of dirty air and water.

Pittsburgh may never have anything as big as the G-20 again, but that isn't a complaint. Nobody will suggest militarizing and emptying the Golden Triangle to make way for more modest gatherings. And this green gimmick may help us with our other convention issue, too.

Not having everyone in the same hotel means visitors will be out in nature, seeing our rivers, our trees, our native jaywalkers. They will be able to work off those big sandwiches they've heard so much about. Walking around is good for you.

The brochures should practically write themselves.