I suggested insulation in the floor so that the warm air downstairs won't rise, making the home more energy efficient. This should also keep the upstairs temperature in check during the summer when it's already hotter up there due to radiant heat. Fiberglass batts won't do much of anything to stop radiant heat from moving around and through the fiberglass, which is why I suggested foam. My attic had R-19 bats when I bought the home, and I gutted it to put in foam. I have a little renovation left to do before that goes in, but I was very surprised at how reasonable the cost is. I'm having the entire underside of my roof (shotgun style house) sprayed at 5" deep, and the estimate is just over $1500; not much more than fiberglass would cost. I'm also not venting; just spraying the foam directly on the underside of the roof.