There are window films available at the apron stores (Lowe's, HD) which will block out some of the UV rays which create the heat in a room. I did a room at my son's house which was my new grandson's some years back. The film looks to be "mirror-ish" from the outside, and definitely darkened the room from the inside. Putting it on was very easy once I did a few panels. There are other types of this film also available from other sources.