I have a shop where I work on projects that need to remain relatively clean, or when I want to stay out of the heat during the summer (think 110F plus). It houses many of my tools and machines as well as my workstation (computer). I wanted to make sure that I had at least a few windows without sacrificing wall space, so I opted for 3 windows above the doors. They let in a lot of light which is nice, but also a lot of heat. The rest of the shop is insulated and an AC unit is in the back wall. The shop stays about 20 degrees cooler/warmer than the outside with the insulation. During the winter, the sunlight through the windows provides enough heat for daytime work without a heater, nighttime requires a heater to keep the shop above freezing since some of the machines are water cooled. The summer though is a different matter, the windows let in too much heat. The sunlight runs right across the side of my head in the morning, annoying to be sure and hot.
My cure? Acrylic inserts. I took some 3mm acrylic that I had and cut it on the laser cutter to a size the would fit in the window frame, but be able to be removed. I left the protective blue film on the acrylic after cutting, although I am thinking that window tint might be more effective, for now though this is working well.