GBSI (Global Building Systems, Inc.) has created a new way to frame a house made of thick foam walls reinfornced with steel members. The process is so lightweight that panels can be carried around by two workers. Then, once set in place, the interior walls can be covered in sheetrock and the exterior walls can be covered in any type of siding/stucco/brick you like. This video shows the constrcuction process and the advantages of the system:
In the video, the inventor claims that a 1,400 square foot house goes from 3.5 tons for A/C (standard construction) down to 0.5 tons for the GBSI system. Heat goes from 120,000 BTUs down to 14,000 BTUs. This page indicates that annual heating/cooling costs for a 1,500 square foot home are $300. That same page indicates a cost-per-sqare foot of $58, compared to $64 for SIPs. One quote from the video:
Anybody can have a net zero energy building. You have to be rich though. The key is to make it affordable, which is what we've done.