Yes, a roller blind creates a still air barrier to reduce heat transfer from the hot side to the cold side. A still air space can be a very effective method of insulation. A Reflective Blind creates a still air space between your room and the glass, this still air space, although not as effective as some bulk insulations, such as one of the foams, makes a significant contribution to the insulation of your room from the heat outside. Additional still air barriers created by your conventional blinds and curtains can add to this advantage.