Open source software for building/designing a house?

Question

Are there any open source tools for building or designing houses? Does it have many features, like calculating costs or simulating extreme weather conditions/aging, etc?

I had the idea to start up a project like this, or join it; I think it would be really neat, but I couldn't find anything on it.

Answer 1

Here's a list of opensource alternatives to autocad.

Answer 2

Red Hat Magazine ran a story a few years back that covered building a house start to finish using an open source philosophy. It includes a few paragraphs on available software tools.

Answer 3

For external views (with weather lighting etc) google sketchup is good.
For engineering drawings any free cad will do, look at the intellicad based ones on windows