Absolutely love these curtains.  I have ordered several pairs in several colors.  They are not completely blackout but they do a very good job at blocking most of the light and weather out.  You can definitely tell a difference in the room temperature when they are up, closed or opened. Same with the light.  without the curtains the room was very bright and hot, with the curtains (opened) the room started to cool off and the light was not as bright.  When I closed the curtains, it was a big, big difference, the room cooled off drastically and it was very dark.