Other ways to keep you house cool in summer are to use silver-sided window shades or outside awnings which let in diffused light, but not hot, direct sunlight.
Get the right sized ones, and they will let in light directly in the winter, but not the summer.
Do a web search for "passive solar" for more info than you will ever need to know. Typically, passive solar design needs to be built into a house, but much of it can often be done with just some awnings.
