We received a few estimates on replacing our metal windows. One company we spoke with said that we wouldn't be happy in a year if we just used replacement windows and would need to replace the whole window. Can you give us your opinion on replacing metal windows with replacement windows?
Amanda, there are various grades of metal windows, but if you have an older home, my guess is that your units are classified as "budget-friendly." There is absolutely nothing wrong with your windows - the issue is more than likely they just weren't very energy efficient even when new. When the company you spoke with said you wouldn't be happy in a year if just the sashes were replaced, that's because the frames would still be a weak point in your home's outer protective envelope.
Modern windows that meet Energy Star requirements have glass that reflects away the sun's heat, but that's just a part of their energy efficient design. The frames are also constructed to keep your home's heat inside during the winter and hot air outside during the summer.
Older windows that might be considered mid or upper level can have their sashes replaced to improve their energy efficiency and their existing frames aren't too much of a liability. However, replacing the sashes on older "budget-friendly" metal or vinyl windows is sort of like making sure your exterior walls have plenty of insulation while the attic has very little or none at all - you'll be losing conditioned air through it.
All this being said, there are ways to make your existing windows more energy efficient without changing the frames. In fact, the National Park Service has an entire article devoted to making historic metal windows more energy efficient. While your windows may not be historic, the same methods can be used. Installing storm windows is one option and adding weather stripping around the frames is another. It is also possible to add another pane of glass to the existing windows.
However, when you figure up the cost of the labor and materials to make the existing frames more energy efficient and then add in the price of the new sashes, the total may not be that much different than installing complete mid-range replacement windows. Don't forget that over time the savings on your utility costs may help pay for replacement windows. And the more energy efficient they are, the quicker the savings can add up. The cost to completely replace the old metal windows may also be partially recouped when you sell your home.