Ordered 2 panels of this for my son's room, who has been complaining that it's too bright and hot in his room. It hasn't been sunny since we put it up, so can't comment whether it will keep his room cooler, but it definitely darkens it completely. Pleasantly surprised by the quality (it's heavy). Love the subtle pattern and color. Only negative was the wrinkles out of the package. It says not to iron, but I ironed it (moved quickly but on hot setting).