Put simply, vinyl windows will not affect your home air quality because they do not offgas in the home, and their environmental impact is minimal if the supplier is carefully chosen and the vinyl is recycled at the end of the window?s use.
Vinyl is composed of an equal portion of fossil fuels and common salt, making it more environmentally friendly than most plastics that are composed exclusively of fossil fuels. The portion of vinyl that comes from oil is less than .3 percent of annual oil and gas consumption worldwide and about 10 percent of annual salt consumption worldwide. While this is not the most desirable and is certainly not sustainable in the long term, the good news is that the raw materials are the worst part of vinyl windows.
Manufacturing and transportation
The vinyl industry has been under constant scrutiny over the past 20-30 years by government, environmental groups, and consumers, and as a result the manufacturing process has improved considerably. Currently, the vinyl production process is essentially a closed-loop process, which means that nearly all waste created in the manufacturing process goes back into the production process rather than a landfill. Further, the embodied energy in vinyl windows is fairly low compared to alternatives like aluminum. the lighter vinyl material uses less energy to transport to its final destination when compared to heavier materials like aluminum.
Offgassing is not a big issue, as the offgassing experienced with vinyl windows is mostly due to the paints and finishes applied to the vinyl and not the vinyl itself. For this reason, it is important to choose your window supplier carefully.
Durability and maintenance
Vinyl windows are very durable -- more durable than wood windows (but less durable than fiberglass or aluminum windows). This aspect adds to its ?green factor? as the fossil fuel use during production and shipping is spread over a longer lifespan.
The vinyl, if removed from the window, can be recycled at the end of its use, though most people do not do so currently. It is estimated that only 1% of vinyl is properly recycled, but it is certainly possible to do so. The recycling process releases small amounts of harmful chemicals in the same way that any plastic is recycled today. The benefit here is that it can be recycled if you have the desire to do so (which you should!), just like aluminum windows. In this sense, these products differ from wood or fiberglass products, which cannot be recycled and must therefore be replaced with manufacturing.
All in all, vinyl products are not great for the environment, but they are not going to negatively affect your indoor air quality and are a viable, fairly green option if the manufacturer is chosen carefully and the product is recycled at the end of its use. We install vinyl windows from Serious Materials when customers are constrained by cost and cannot afford to install fiberglass windows.
To take a step back, I would ask you to consider the reason you would like to install new windows. If it is to create an energy efficient home, I would say that windows are usually not the best way to accomplish that goal. At Recurve, we frequently field calls from customers about windows, and once we create an energy model for their home they decide to put their money where they can have a much greater energy and environmental impact (not to mention comfort and health benefits) by investing in things like air sealing, insulation, and HVAC optimization. Before investing in any home performance solution it is always advisable to invest in a home energy audit so that you can be confident you are making the best choice for you, your family, and the environment.