had ours replaced about 28 years ago that had argon gas filled between a double pane to keep the heat outside during summer days....................it worked until it didn't as all of the gas leaked out. iirc, it was anderson windows. the bigger issue is that replacement windows aren't made like new install type...............doesn't have the flange on them.............unless you remove the brick or other exterior coverings to do so. no amount of caulk will ever keep the dirt and heat/cold from coming in. to me they cost more and are worth it..............just ask my wife! 6 windows @ $10,000...........what a joke! 1 was a 5x6 another 5x8, 3 were 3x5 and 1 was 2x3