We have a two story house with a wall of windows in the living room, which is open to the second story. The windows face the sun all afternoon and it gets very warm, even with AC on. I use SunCalc to check when the sun is beaming into the living room. If the AC is on, I want the windows closed during that time. If it's winter, I may elect to open them during that time to help with heating.
I close them again in the evening when it is darker outside than it is inside so my neighbors can't see in.
The windows can also cause glare on the TV screen. I haven't implemented this yet, but I think I'll have the blinds close when the TV is on if the sun is coming in from that direction.
Lastly, I have the blinds close when we are not home. Maybe this makes no difference, but the UV from the sun causes the floor, furniture, paint, etc. to fade over time. No need to let more UV in if we aren't home to enjoy it.
