The insulation thread had me thinking more and more about adding a radiant barrier in my attic. I recently moved my office from our main level upstairs into a room that I have always had trouble heating and cooling. The room is adjacent to my attic and was finished out when I built the house. The attic in the summer gets unbearable. I have a power gable vent, perforated vinyl soffit and ridge vents. The new office has the standard batt R19 on the knee walls and ceiling. It's about 15 degrees hotter up here than downstairs. The room is about 700 sqft and has 2 HVAC vents and 1 return. One wall has 2 large windows facing west with full sun all day. I'm looking for opinions on properly heating and cooling this space. Would a radiant barrier like AtticFoil.com make any difference? I am not opposed to reinsulating this space or even adding a second HVAC unit if I have to. I just don't want to spend the money on the wrong thing up front and have to turn around and spend more because the first thing did not work.