One knock on sustainable housing is that it’s pricey. Green is good, some say, but only for those who can afford it. Not at EcoUrban Homes, a St. Louis start-up that’s bringing green to the masses with LEED Platinum–rated prefabricated homes for urban infill sites throughout the city—and maybe other markets in the near future.

With 90 percent or more of its homes built in a modular housing factory 75 miles away, including builder-specified expanded foam insulation in the walls and no-VOC interior paints, EcoUrban can deliver a near-finished home for about $100 per square foot, excluding land. The result: houses ranging from a 1,000-square-foot, one-level, three-bedroom model in the $130s to a 1,900-square-foot stacked modular in the mid- to upper $200s—prices normally found only in the city’s outlying suburbs, not close-in neighborhoods. The quality of the 2x6 insulated shell, derived from off-site construction, enables the builder to maintain a practical yet highly effective approach to energy and resource efficiency. “Because the homes are so tightly built [from the factory], it brings us a long way toward green” before any ­on-site mechanical and finish work is done, says Nate Forst, head of project development. “Prefab is the way of the future for home building, anyway, and it lends itself to green.”

Once the homes are assembled and closed up (a process that typically saves weeks in cycle time, ­further enhancing affordability), the builder calculates and right-sizes a conventional (if high-­efficiency) forced-air HVAC system, complete with insulated and sealed ductwork. That combination results in much lower cooling costs­—during St. Louis’ sweltering summers, for instance—a benefit and cost savings not achievable with conventional construction nor for others at EcoUrban’s price point. “The utility costs are almost negligible, and the homes are comfortable and healthy,” says Forst.

Meanwhile, site-applied finishes, including bamboo flooring, fiber-cement exterior claddings, and recycled-content engineered decking, also earn credits under the just-released LEED for Homes rating system, a significant step up from the market’s HBA-sponsored green building program standards or ­Energy Star. “This is an ­active green building market, and we want to be the leader,” says Forst.

The most significant factor in achieving LEED certification and being sincerely green, however, was leveraging the scattered, narrow infill lots in some of the city’s older neighborhoods, primarily the result of teardowns. “There’s a push to get back to downtown St. Louis,” says Forst. Close-in lots in neglected or aging neighborhoods have become affordable and thus ripe for reinvestment. “It’s still a fringe opportunity, but there’s momentum.”

By design, and because of its prefab approach, buyers can find their own infill lot or EcoUrban Homes will help buyers find lots for its trio of available plans. The builder is using its first house, completed last summer, as a furnished display to spur interest and sales, and it has two more homes under construction to promote its other models. “Building any more spec homes than that doesn’t make sense in these market conditions,” says Forst.

The off-site building and on-site finishing scheme also allows EcoUrban to either maintain the modern aesthetic it offers off the shelf or adhere to more traditional exterior materials, such as brick, to complement existing homes in a given neighborhood. “The homes are very easy to adjust to a given taste,” says Forst.

Such flexibility, combined with a prefab, green ­approach that suits infill parcels and meets high-performance building ­standards, has Eco-Urban Homes attracting attention within and outside its home base. The company has been approached to modify its smallest plan for stacked rental housing on another urban parcel and has taken notice of similar LEED-friendly opportunities in Chicago, Denver, Nashville, Tenn., and Austin, Texas.—R.B.

Learn more about markets featured in this article: St. Louis, MO, Austin, TX.