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Michael Kiefer vets some cabinets. (Lydia DePillis)

Michael Kiefer, founding principal at GreenDC Realty, doesn’t just know housing. He knows houses.

Walking in to an older building, he’ll step contemplatively over a floor, detecting an ever-so-slight arch or sway. Regarding an external wall, he can tell you what’s fire damaged and where windows used to be. Even with relatively new units, he can figure out when they were last renovated without an agent’s brochure.

“You can usually tell by the appliance,” he says, peering into a dishwasher as if he were aging a horse by its teeth.

Knowing the guts of buildings isn’t something you learn in realtor school. After finishing a Peace Corps tour in Ukraine, and a stint on a dairy farm in Finland, Kiefer became a builder himself, working on green housing construction—until he found it was “dirty, too expensive, and took forever.”

GreenDC Realty, which markets enviro-friendly developments and serves buyers looking for the same, is something of a middle ground. Kiefer now has four employees, and last year did $7.34 million in sales. He’s the real estate end of CoolTown Beta Communities’ crowdsourcing enterprise—the idea is that you bring “creatives” together online to build support for neighborhood-based green living projects in the real world.

Even if that sounds like a bunch of marketing mumbo jumbo, Green DC Realty provides one service that’s worth infinitely more than its price: a weekly free tour of condos concentrated in a small area. With no obligation to buy, anybody can show up and accompany an agent on a scavenger hunt through properties for sale—some of which are still occupied by tenants while the owner has them on the market.

“With the way the tenants have it, you’d have to have a lot of vision,” Kiefer notes dryly, surveying a two-bedroom in Logan Circle. Another is neat as a pin—Asha Maskiell-DeMarsh, one of Kiefer’s recent hires, notes that it’s not infrequent to see places, like this one, lined with wedding photos.

The realtors get the occasional sale out of guiding people around for free, but they’re also just for their own benefit, giving a sense of what’s on the market in a given neighborhood. And at the moment, no one else is offering them. Kiefer should know—he trademarked the phrase “DC Saturday Tour of Homes.”

“I didn’t want the idea getting distorted,” he says.