The newest proposed hotspot for micro-housing: parking lots.

Elevate Structure, a Hawaiian tiny house company, envisions adding compact and affordable housing in cities around the U.S. — without sacrificing parking. The firm’s pre-fab design props the small dwellings on top of a trunk-like base so they float over the asphalt. Add “tree trimmings,” with exterior walls finished in leafy greens to reduce air pollution and a roof that funnels rainwater into the hidden storage tank in the “trunk,” and you’ve got sustainable architecture in the mix too. (That stored water also helps weigh the little structures down.)

Fast Company notes- that with an estimated two billion parking spots in the United States, many are often empty. “It’s just an incredibly underutilized space,” Nathan Toothman, co-founder of Elevate Structure, told Fast Company. “There are massive, oceans of concrete. In some cities, I think a third of the area is parking lots. We’re trying to bring more usage into that area.”

The base of the houses would be 40 square feet, with rooms at 250-400 square feet.

The startup is raising money to build a demo on Kickstarter.