[mrtksn]

I don't know the details but it worked out very well for me. It still lets some heating rays in but its much more manageable, some ventilation is enough now.

These photos shows how much the film dims the visible light: https://dropover.cloud/999162

The photo of the wall shows two areas, one area illuminated by the light passing through the filter and another small area illuminated by direct sunlight through the opening.

It's a window in a small room. The window has a top-open position which provides enough ventilation to take away heat that still manages to get in. Previously, this room was getting unbearably hot and now is much better(still hot on days with no wind though).