Thirty seniors from Cedar Rapids-area high schools are building an “eco-house.” For the past 27 years, the Cedar Rapids School District and the region’s realtors have joined forces to have students build a home to gain experience in the building trades. This year’s house, though, is different — it’s using “green building” techniques.Dave Smith is the building trades instructor who teaches the kids on the construction site. Smith says they are installing energy-efficient windows and special carpeting. Smith says there is very little plywood in the home.The home’s shingles are laminated and should last 40 years, which Smith says will cut down on the number of shingles which end up in the landfill.Smith says they’ll hold an open house in the spring, showcasing the “green building” techniques to area builders, then the place will be sold. The project was financed, in part, by a 51-thousand dollar grant from the state’s Solid Waste Alternatives program.