Here are some of the columns I’ve written about this.
The Sun List. — a great graphic in this one about heat gain. You’ll be surprised.
And, just because you made to the end, if you give me your name and email, I’ll send you my Window Covering Decision-Making Guide. It’s got a lot of easy-to-read info on the most common types of window coverings on the market, what they do and what they don’t do. The process to get the guides is a tad ridiculous, I apologize. I am trying to find a new way, but please go through, I know the guide will be useful.