As much as I love Blender, I don't think Blender is very good for "design". It lacks parametric solid modeling primitives and operators. I've tried many times to do architectural modeling in Blender. It's good for sketching and rendering stuff like that, but not so much for "design". It's just not streamlined and is missing too much fundamental stuff. Some day, I'd love to see Blender improve in that regard! Someone recently made an addon called "archimesh". There's also "sverchok", a parametric modeling plugin. I suppose that could be used for design. And of course, if you're writing your own python scripts, the sky's the limit.
I think with a couple basic improvements, Blender could crush as a design tool:
1) Comprehensive solid modeling tools, including quality measuring tools for volumes, surface areas and lengths.
2) Some kind of plugin or extension to allow for composable, parametric "widget" type object groups. So you'd have a parametric wall section composed of parametric material pieces. The window unit would be a parametric composition of parametric subcomponents, like layers of glass, a tweakable frame, etc. A window widget would know to boolean cut through a wall. Archimesh does this kind of thing, but it's buggy and still in beta, and not so general purpose. Maybe Sverchok and some python would do it.
Along with Blender's excellent constraint and modifier system, these would go a long way.
Edit: I Just remembered that there was (and maybe still is) a long term push for "node based everything". I think this might fulfill #2.
I think with a couple basic improvements, Blender could crush as a design tool:
1) Comprehensive solid modeling tools, including quality measuring tools for volumes, surface areas and lengths.
2) Some kind of plugin or extension to allow for composable, parametric "widget" type object groups. So you'd have a parametric wall section composed of parametric material pieces. The window unit would be a parametric composition of parametric subcomponents, like layers of glass, a tweakable frame, etc. A window widget would know to boolean cut through a wall. Archimesh does this kind of thing, but it's buggy and still in beta, and not so general purpose. Maybe Sverchok and some python would do it.
Along with Blender's excellent constraint and modifier system, these would go a long way.
Edit: I Just remembered that there was (and maybe still is) a long term push for "node based everything". I think this might fulfill #2.