im sure this has been answered on here before, but here it goes. I have a home with a converted garage right above 400sqt of space. it has a ductless ac system now. we want to use this as an office/multi purpose room. it has the ventilation at the top, that goes through the attic into outside via piping. as far as a living space, i'd like to just place CO detectors and block the water heater from the children with plantation shutters/ louvered. is it a must to enclose and vent to outside, sealed, being is in such a huge room?