uPVC Windows have captured an ever increasing share of the replacement and new construction window market and with good reason. uPVC windows and doors fill a need for energy efficiency that the old standard single pane aluminum/wood sash window can't handle. As energy costs have raised through the years so has the demand for uPVC windows. Old loose fitting drafty wooden/aluminium windows are a major source of heat loss and air infiltration.
Initially aluminum replacement windows seemed to be a natural choice to replace the old wooden sash. But ultimately aluminum windows are not well suited for residential use. Unfortunately although aluminum is structurally very sound it also conducts cold/heath to the inside of the house causing major problems with condensation causing corrosion and mold growth. That's where uPVC windows come in, the uPVC window material is very similar to wood as far as its thermal efficiency, but it is virtually maintenance free and will newer corrode as aluminium windows.