One trickle-down effect of the green revolution is the growing recognition that social and economic sustainability should be part of the picture. KRDB of Austin, Texas, aims to cover those bases at SOL (Solutions Oriented Living), a mixed-income community on the city's east side. The parameters are impressive: a 5.5-acre tract of 40 units on 38 lots within walking distance of schools and commerce. Most of the homes will produce as much energy as they use over the course of a year, and 16 units are reserved for families at 40 percent to 60 percent below the city's median household income. “The goal for this project was a broader and more holistic definition of sustainability,” says principal Chris Krager, AIA.

SOL is the design/build/develop firm's largest project to date, and Krager spent two years doing cost-benefit calculations and puzzling together a development model that has many moving parts. Local subsidies of $1.4 million reduced the out-of-pocket costs of the $8 million project, and KRDB traded some profits for security by preselling the 16 affordable units at a below-market price ($150 per square foot) to the local Guadalupe Neighborhood Development Corp. The group, which hopes to hold them in a 99-year land trust, will sell half of those units and manage the others as rentals.

The market-rate homes, constructed with SIPs, rely on passive and geothermal heating and cooling, solar arrays, and other measures to achieve net-zero energy use. Affordable units feature modular construction with 2x6 exterior wall framing and will include solar panels or solar-ready wiring, depending on whether additional grants come through. All the 1,000-square-foot to 1,800-square-foot homes are stylishly modern, with metal roofs and stucco, fiber cement, and wood exteriors.

KRDB broke ground on the houses last December and plans to finish up this summer. “We see this as a transportable model,” Krager says. “We're looking around the country for another city that has the right set of circumstances and incentives to do our next SOL project.”