Hi! I searched the forums and didn't see this one. I am putting up some tension-rod window coverings at my teenagers school bc last night at back to school night, it was still 90 degrees in there. BIG tall bank of windows facing the south and the blinds seems to act as a heat conduit. I used Outblack on my own huge (204") kitchen window and it works amazingly at both heat and cold.... BUT it is dark when it is down. There is something called Thermoblock which supposedly lets in light, but not the heat, but I was holding the bolt in my hands, thinking, it just feels too wimpy to do the job. I bought 1 +/- yard of each to 'try' but I figured someone here as already gone down this road. It is supposed to hits the 90's all week, so I am trying to quickly turn this around for the kids. Any suggestions? Thanks!