Our design process is collaborative between all those involved, with us sending out sketch-up models to all concerned during the design. This way our PHPP guru and MVHR designer can have their input into the frame - so improvements to cold bridging details can be incorporated by modifying details around junctions. MVHR duct holes are also all pre-cut in the frame, so they can all be in the joist zone. The alternative, conventional industry approach is for the MVHR ducts to be worried about after the event - meaning ducts have to be boxed out in corners of rooms etc