There are no Goodwill stores in downtown Washington, D.C., where commercial rents are the highest in the country. But perhaps there should be, if the performance of a recent pop-up shop is any indication.

In August, the national non-profit thrifting outfit put on its first short-term store event in a gallery space owned by the electric utility Pepco, with help from Gensler in designing the layout. The architecture firm's design won an internal company award for its color-coordinated configurations, beating out hundreds of big-ticket projects. More importantly for Goodwill, the 2,000-square-foot pop-up brought in eight times the revenue of one of its normal retail locations, which are five times the size—even though the clothes stayed priced at the two-buck tank top level.

Naturally, Goodwill decided to do the event again, this time with a holiday-themed downtown pop-up, at 702 Eighth Street NW. Gensler obliged, donating the time of a couple graphic designers, office architects, and a cultural anthropologist to put together a wintry-themed boutique that's open through Friday, Dec. 14. Delicate paper cranes were pasted on the walls and suspended from chicken wire on the ceiling, while chiffon bows and shoes for sale topped piles of spray-paint-stenciled cardboard boxes. Wisely, they also avoided playing the kind of irritating Christmas music that suffuses the rest of the downtown shopping experience this time of year.

"This is something really special. It's not just, you run in and start scouring the racks," says Gensler team leader Bonnie Sen, AIA. Still, back in August, they ran out of clothing. "This time, we brought a lot of merchandise," Sen says.

This isn't the first time Goodwill has found sales success through its store appearance. Six years ago, the Washington region retained the interior design firm OPX Global to overhaul its 13 retail stores, adding spacious dressing rooms, displays narrating Goodwill's mission, and a cheerier color palette.

"What we're trying to get away from was people seeing Goodwill as a dirty old thrift store," says chief marketing officer Brendan Hurley. Apparently, it worked: On average, each Washington-area store made 11 percent more revenue from 2010 to 2011.

Oddly, Goodwill's downtown pop-up may have done more sales volume by putting less merchandise out at any one time. There were only a few long racks of clothes in the space, far from the claustrophobic chaos that characterizes your typical thrift emporium. The items were culled from Goodwill's stores in the area, lending the collection the sense of order and curation that also characterizes the other successful stores in D.C.'s burgeoning vintage scene.

Nicole Aguirre, editor-in-chief of Worn Magazine, helped promote the Goodwill pop-up, and offers the example of another neighborhood thrift shop that upped its sales by paring down its offerings. "I think in that case, less is so much more," she says. "That's a draw for me, that everything's already been picked through."

Hurley says the most profitable stores are actually located in the wealthiest areas. Not because wealthy people shop there, but because less-wealthy people will travel an average of 30 miles to get to a location that they know will have a good selection of high-end castoffs. By that metric alone, a permanent shop in downtown D.C. would do quite well indeed.