R-value of half-inch glass
I'll bet someone here knows the answer to that question. We came across 7 sheets of 3'x5'x.5" tempered glass from the front of a remodeled bank. They weigh about 60 pounds per sheet.
I tried googling the answer to no avail.
In the middle of a major home-remodel, we substituted one of the panes for an exterior door that had to go. Great view and the houseplants love it!
To us, it seems as good thermal-wise as the double-pane insert with enclosed blinds in our front door. In other words, a hand on the glass in sun is as warm on one as the other. In some late frosts earlier this spring, only once did it have a spot of frost on it.
We'd like to use several of these in a sun-room addition if they are at least close to double-pane in R-value.