Structral Insulated Panels, or SIPs are touted as a great green alternative. They're thick, they're built in a factory so there's superb quality control, and they let you put the walls up quickly. There's very little thermal bridging, and they use far less wood than conventional framing. So what's even greener? SIPs with straw as insulation, or bioSIPs.
It's an intriguing idea. I'm going to tour the EcoHome in Niagara next week, to see if it's for us.