replacement glass in existing frame
I usually lurk on a different forum, but I have a question that I hope you can help with. We have two large fixed glass windows (about 5-ft x 4-ft) above our front door. The frames are good, and are mahogany, like the rest of the window frames in the house. The windows do not leak water or air, but nonetheless, there is a cold draft off of them in the winter.
I suspect that the best solution would be motorized cellular blinds to cover the windows in the winter, but my husband thinks replacing the glass in the windows would help. We currently have 3/8-in. double with low-E coating, and a glass company could replace with 5/8-in. low-E. We live in New England, and these windows are sheltered, but face north. My question is whether this would be worthwhile. For example, when replacing the glass in an existing frame, how does the installer ensure an air tight seal?
Thanks so much for your help.