Down a long and meandering dirt road surrounded by woods and sky, with the promise of water drifting in the summer air, the “green” house that Kel House built appears around a final curve, overlooking Penobscot Bay. Using an insulation technology called , or structural insulated panels, the 1,500-square-foot home is constructed not with the typical timber framing of a post-and-beam building but with panels of rigid foam laminated between layers of structural board.