uPVC windows, vinyl siding or rigid vinyl windows as they are often called around the world are made from unplasticised polyvinyl chloride. Whereas timber frame windows are obviously made of wood. Both window types have their drawbacks and advantages.
Unplasticised polyvinyl chloride is a plastic. And it is this fact that is at the heart of the problems with uPVC windows. Plastics are notoriously hard and expensive to recycle or dispose of safely. In many countries unwanted plastic just ends up in landfill sites. Vinyl windows are made from PVC. The US Environmental Protection agency classes the dioxins that are given off in the production of PVC as carcinogens. Furthermore, if vinyl windows are burnt they give off carcinogenic dioxins. This is worried news if you consider the possibility of house fires and also the reality that many fires occur in landfill sites where the majority of unwanted uPVC ends up.
In contrast timber frame windows are much easier to dispose of at the end of their life. The wood can be recycled, burnt to make energy or allowed to biodegrade. The only environmental problem with timber frame windows is that timber is a precious commodity and deforestation is a very real threat to the future health of the planet.
Putting aside the environmental issues surrounding uPVC windows and timber frame windows, it is clear that in other respects vinyl windows are better. Timber frame windows are subject to continuous damage by the extremes of weather. Too much rain will make the wood rot. Too much humidity will make the wood swell and too little moisture will make the wood shrink and crack. It is necessary to constantly be repairing timber frame windows to ensure they last.
Whereas, uPVC windows are imperfect to the changing conditions of the weather: they will last for over 25 years with minimal maintenance required.
Timber frame windows are bad insulators. They let out a lot of heat in the winter and allow in a lot of heat in the summer. In comparison uPVC is a good insulator. Installing uPVC window frames with double glazing will significantly reduce your heating and cooling bills.
Wooden frame windows provide a soft target for house breakers. It takes only a matter of seconds to open a timber frame with a pry bar. Compare this with uPVC windows which provide no place for a pry bar to gain purchase and are very difficult to force open. Furthermore double glazing is not easy to smash through. On top of that most new uPVC windows come with multi-point locking systems as standard.
Finally, in America, Ireland and the UK homes with uPVC windows are generally easier to sell and go for more money. In short because of the energy saving and improved security aspects of uPVC windows they make a house a more desirable investment.
Thus, it is hard to decide which is more important – the environmental concerns with uPVC windows or the obvious financial benefits that they confer. The future for these type of plastic windows may depend on such recycling processes as Texiloop developed in Europe and Vinyloop developed in Japan which can safely recycle plastic without releasing polluting dioxins into the environment. At the moment these technologies are very expensive. It is a shame because the insulating ability of vinyl windows means that they can be used to reduce the emission of greenhouse gases from powerplants that burn fossil fuels to generate electricity.