You are welcome.
see the post above this one, I just asked
Dela Where if those cheap emergency blankets would work, as they can be bought for a couple dollars and are silver colored on one side, for the walls and floors.
>>>if those cheap emergency blankets would work<<<
Sure would... All you are looking for is the reflective surface to keep reflecting the light. (like pong...) till it is absorbed by the plants.
You can buy 4’ X 150’ rolls of 1 mil mylar for about $40
NOTE: Don’t completely seal the whole room and then spend the whole day in there working away... crack the window a bit... Not only for your breathing, but because you want to avoid mold behind the mylar.
Also, you will have a higher humidity than your normal house has in the wintertime (transpiration). Watch your plants for water needs as they will dry pretty fast.