If you’re not interested in replacing your windows, there are a couple of things you can do for your existing windows. You can apply caulking and weather-stripping to reduce air leakage around windows, or apply window treatments or coverings to help reduce heat loss or heat gain. These solutions are never as effective at reducing air leakage or infiltration compared to new windows. You can save more in the long run when you replace windows as opposed to constantly trying to improve them.