We have evaporative ducted it is good and cost effective, but it will only keep the inside temp around 10 degrees lower than the outside and you do need to have windows open for it too work effectively. Like feeb said when it gets extreme it won't give you the ice box cooling effect.
If you don't get good flow through already you might want to ask a tech type person to check if it will run effectively with out air flow through the house.
You might end up better off with another sort of cooling?
Good luck