Reading through the manual on Buildings, it seems that the CF values for buildings are a flat value regardless of the size of the building's foot print.
As an example, in regular battletech, a Building's CF is on a per hex basis, so a 1 hex building has a CF of X, and a 4 hex building has a CF of X per hex, and would only require the destruction of 2 hexes to eliminate.
However, in AS it appears that a buildings CF is that amount regardless of how large the building is. a Building that is 2" x 2" (rough equivalent of a Standard BT hex) is X, a 4" x 4" building (or 4 BT hexes) is still the same CF.
In fact, this makes large buildings easier to destroy in AS as a unit merely needs to get close to any point of the building and start hammering away, even if that point is the furthest point from another part of the building also taking damage.
Just wish to ensure I am not missing something here.