There are a lot of reasons why people may come to need a window replacement. They could be beginning to invest in double or triple glazing windows to help them save money in the long. There are a number of problems with double glazing which can occur, such as trapped condensation between double glazed window panes or damaged seals, which can require work or replacement as well. Then there is also the aesthetic factors to consider as well, with people wanting to change the look of the exterior of their home.
Replacing is typically done as some form of an exchange arrangement, whereby your previous windows are exchanged for your desired window product, which can help to greatly reduce the costs of the new windows. In fact, replacing undamaged double glazed windows which have trapped condensation with a new set can be done quite easily for under £50 virtually anywhere in the UK.