+1 to roller black outs. I have one on my office window (just a cheap Ikea job). That is West facing and even in the warmer spring we had a week or so ago, with it open my office was uncomfortably warm. On the next, even warmer day, I kept it closed and the room was positively chilly.
It could also be the type of window(s). My office only has one, but it's a tiny room and the window is 6' tall by 2.5' wide, so the glass to wall to room size ratio is relatively big but it is a new double glazed number.
+1 to roller black outs. I have one on my office window (just a cheap Ikea job). That is West facing and even in the warmer spring we had a week or so ago, with it open my office was uncomfortably warm. On the next, even warmer day, I kept it closed and the room was positively chilly.