I like prefab house alot. Normally, prefab house requires several aspects: -
1. It’s aesthetic requirement.
2. It needs to look nice, cute and preferably small and clients are normally young couples or younger generation that prefers high-tech stuff.
3. Its’ well-thought and neat consideration of the living conveniences that pre-fabricated into the house.
4. Its’ easy to construct and installation cuts down the construction time
5. It can be seen and modified easily at range provided by the designers, and made to save up time.
6. It can even grow and assembled with several prefab modular houses depending on site area.
In short, it has to be user friendly, good looking, cost effective and a huge time saver from all aspect from design decision to site construction. I would love to get myself one of these in the future. Maybe design one for myself and turn it into a product to share or sell. My comment on zeroHouse would be the roof~! It should allow sun to come through. Glass or trellis is better solution then metal deck.
"The zerohouse was the only winner of a 2007 TSA Studio Award. The Studio Award category encompasses all unbuilt and theoretical work. Images of the house will appear in the October 2007 issue of Texas Architect magazine, and the house will be presented at the TSA convention in Austin. http://texasarchitect.org/news_detail.php?news_id=116&sess_id=c717d8987367465ea523cad06eb1f537" 
Passage from http://www.spechtharpman.com/Images from http://www.zerohouse.net/