I live in an old School House. The Windows are 8' x 5.5' and I have a total of 176 panels. They are original to the bldg. and are single pane. I was wondering if I put another pane of glass up against those if they would be sufficient to stop the MANY air leaks that I have. The Frames are Metal. This is a DIY project and due to a loss of over 25% of our income I must do this as inexpensively as I can. If I have to go with double pane does anywhere know where outside of retail I can get that much glass? Thanks in advance for any assistance that you can give to me.....Dana