I know that vaulted ceilings are designed to let light in to the foyer but they also let in heat.
I've always felt like it is wasted space. I think that it would have been a better use of space to make the master bedroom larger. The level of heat that comes off the window is ridiculous. So I decided that it needed to be covered with black out shades. There were two problems with my solution.
The first is that it is very expensive to cover a 60 inch window and the other is that it has to be hung up and there is no easy access.
The solution that I found was to buy mini blinds and turned them into roman shades. I found some blinds on the clearance table at Lowe's for $15. They were two inches short. But I felt that I could compensate with fabric to close the space in the window.
Jo Ann's Fabric had black-out on sale for 40% off so I purchased a couple of yards. I had some Tan colored fabric at home that would be a good choice. Then I removed all the slats from the blinds, all but 10. I doubled them up for strength. and hand sewed around the slats spaced about 10 inches apart. This way I would have 5 folds. I think it came out pretty well and it does reduce the amount of heat that comes in.
Kit pulled the ladder from under the house and I held it as he cursed the heat and the drill as it was installed. The only downside is that I do have to get on a step ladder to adjust it.