sizing holes for exhaust and fresh air intake pipes
I am building an underground house via poured in place concrete. Walls and roof are 10 inch thick concrete so I have to locate and size holes for exhaust and fresh air intake vent pipes since post drilling of holes is not an option. I need to:
1. size the vent pipes for maximum of 1000 cfm
2. is it possble to do one pipe with concentric exhaust and air intake pipes in one unit?