So we currently have a slab on grade home drawn using a frost protected shallow slab and vented roof assembly in climate zone 7. The plan is to use mini splits as the heating and cooling. We had also hoped to use a Zehnder HRV. 

Current issue is that plans don’t allow for ducting to reach all the necessary rooms. An interior chase doesn’t really work well either with the layout. 
Could we create a insulated chase in the attic/trusses? Or run those Zehnder ducts at the bottom of the insulation? We plan to insulate the attic to an R-70+. 

Thoughts and ideas greatly appreciated!