Just went through some of this myself. The R value of very good triple pane glass is R5 or so. About the same R value as a wall made of 2x4s with no additional

Just went through some of this myself. The R value of very good triple pane glass is R5 or so. About the same R value as a wall made of 2x4s with no additional. Or about the same a 1” of extruded foam. So… pretty poor.