Is there open source plans?

It seem to me that we could have open source full plans for a few models of cost effective houses.

Then builders and prefab manufacturers could bid on the price and selection of parts to build it.

The houses I see builded here are terribly inefficient. Complex shape and roof lines with a lot of unused space. They are made to look like an old house that was upgraded multiple time instead of being one large rectangle or square with simple roof. Furthermore the ratio of exterior walls to inside space is far from optimum, resulting in larger material and heating cost than necessary.