Rain Screen Siding Guide
Walls that can drain and dry last a lot longer than walls that stay wet. An air gap between the siding and sheathing lets both dry independently.
There are many ways to create an air gap between yhr back of the siding and the drainage plane of the wall (WRB, exterior insulation, surface of ZIP Sheathing), here are at least a few options.
Size up the Job
Why a rain screen wall is important to the energy and durability detailing on a Passive House.
As the 2015 IECC works into jurisdictions, required R values will eclipse what you get between the studs. In more areas, insulating on the outside of houses will become reality.