With gray clouds overhead and a biting wind whipping across Tucson's desert hills, many Arizonans early this Saturday are indoors, sleeping in. Yet, the roar of a concrete mixer beckons a hardy group of volunteers who huddle against the chill while drinking coffee and hot cocoa at a house construction site in a new development.

Ladders and scaffolds, piles of sand, bags of cement, and debris crowd the house construction site. The walls of the home are up, and the stuccoing is about to begin.

Before the work day starts, however, the group convenes in the backyard, away from the din of the mixer, and forms a circle. They bow their heads in prayer, asking for safety during the day's work and for blessings upon the house and the family that will occupy it.

It is a familiar Habitat for Humanity construction project, save one thing: You won't find lumber scraps and leftovers. That's because the blueprints didn't call for 2-by-4s, but for 22-inch-thick straw bales for the walls. In fact, the straw makes up 13 percent of the construction materials.

The straw-bale home, constructed by volunteers with Habitat for Humanity, Tucson, is part of a model project to demonstrate how straw can be coupled with solar energy to build better homes at a lesser cost for low-income families. Habitat Tucson was chosen by the city government to partner with the Tucson Urban League for the model super-insulating, straw-bale home effort. Habitat also received a grant from the National Urban Consortium to help with the construction costs.

Low cost, low maintenance A house of straw? It's no longer just for the three little pigs. As modern research has discovered, straw-bale homes provide temperature insulation three times greater than conventional new homes. ...