Replacing the old glazing units with like for like glass; or upgrading to more energy efficient glass, is much more economical and environmentally friendly than fitting new frames. The savings can run into thousands of pounds. However, this all depends on the age and state of the current frames and the type of window. For example a bay window costs a lot of money thus replacing the glass would cost a fraction of the amount. If the window is in good condition then replacing the glass is definitely worthwhile and will give you many more years out of your windows. Imagine if your car clutch was faulty, you would not buy a whole new car if the condition of the current one was ok. The concept for windows is just the same.
We do always aim to give honest advice, so if you are unsure just give us a call and we can recommend the best solution to your problem.