Well, the answer is to do some checks beforehand and here are a couple of pointers.
Getting cheap double glazed UPVC windows are definitely a good idea because the material itself is very durable. UPVC is resistant to corrosion, and it can last for many years. If you are looking for affordable UPVC windows, then here is the chance to learn more
By the way, although the Green Deal covers about 40 or so home improvement categories, unfortunately, it does apply to the installation of double glazed patio doors and windows.