3M makes a promising looking film. UV and high intensity LED safe, adhesive backed. 98.5% reflective.
https://multimedia.3m.com/mws/media...ta-sheet.pdf?fn=Specular Film SFP-D50A DS.pdf
That stuff looks like you would have to wear sunscreen and solar eclipse glasses just to be in the room!
One thing that has been tickling our brains is how we are going to cool the room over the winter. Since right now we are using the duct work and the AC from the house. We were thinking of a portable AC unit. Roughly 15,000 BTU should do it. I would want to oversize it so it wouldn't be running constantly and dehumidifying the room. I am bringing this up since I do believe making the room more reflective would make it so it would be hotter in there. Right now I am surprised with the fact that it is staying perfect temps without having control over it.
We also did some research on making/obtaining/purchasing packaging for seeds, you know just in case we want to sell seeds or something later on. Found some awesome pictures and came up with some awesome ideas on names and such. The artwork and drawing we have taken care of by a friend here...just need to source a printer to make the packaging.
Time to go chop and hang some plants!