We are researching options for our windows on our house which was built in San Francisco in 1924. It is hard to trust different contractors trying to sell us different things. The question is: is it significantly more energy efficient to replace the windows with brand new vinyl ones compared to repairing and weather stripping existing ones? some of the sashes on some existing ones are actually not the right width, and someone told us that just getting the right width piece would go a long way. On the other hand, folks who sell new window installation only tell us that of course it's so much more energy-efficient to get double pane windows. And someone is arguing that since the house is (unfortunately) not that insulated anyways, new windows will only make a small difference. I need some opinion from a neutral person.