uPVC and the environment, plainly.

uPVC is a plastic made from salt and fossil feedstock. It lasts a long time in a window, it needs no paint, and it insulates well. It can be recycled, but in North America most of it is not yet. Its chemistry has real critics, and they have fair points.

What it is made from.

PVC is polyvinyl chloride. More than half of the polymer's weight is chlorine, which is made from salt. The rest comes from ethylene, which is made from natural gas or oil. So PVC uses less fossil feedstock per kilogram than most plastics, but making chlorine takes a good deal of electricity.

The *u* stands for unplasticized. Flexible PVC, the kind in cable sheathing and flooring, is softened with plasticizers. Window profiles contain none, which is why they are rigid.

Unplasticized does not mean free of additives, although that is often said. A window profile contains heat stabilizers, impact modifiers, and pigment that protects it from ultraviolet light. The stabilizers are the part to ask about. Older profiles, in Europe especially, used lead-based stabilizers. Current ones use other systems.

How long it lasts.

This is the strongest point in uPVC's favor. It does not rot and it does not corrode. It needs no paint or sealer over its life, so there are no coatings to renew and no solvents used in renewing them.

A long life spreads the impact of making the window over more years. But be clear about what wears out first. In any modern window, of any material, the parts with the shortest life are the gaskets, the hardware and the sealed glass units. A frame only delivers its full service life if those parts can be replaced in it. Ask whether the glass can be changed from inside, and whether gaskets and hardware are kept available.

What happens at the end.

uPVC is a thermoplastic. It can be ground up, melted and extruded again, more than once. Two things are true about how that works in practice.

• Factory scrap is recycled as a matter of course. Offcuts from profile extrusion and window fabrication are clean, of known makeup, and have a ready use. Recycled material usually goes into the core of a new profile, with new material on the visible faces.
• Old windows are harder. A window taken out of a building is a frame, glass, steel reinforcement, gaskets and hardware, and these have to be separated. Parts of Europe have collection schemes that do this at scale. North America mostly does not yet, and old vinyl frames here usually go to landfill. Old frames that contain lead stabilizers add a further complication for recyclers.

So recyclable is accurate. Recycled depends on where the building is and who takes the old windows away. On a replacement project, that is a question for the demolition scope.

Operational energy against embodied impact.

Every window has two environmental accounts. The embodied account is spent once: making the materials, building the window, shipping it. The operational account runs every year: the heating and cooling energy the window loses or saves.

Windows are where the building meets the sun and the cold. They admit free heat in winter and unwanted heat in summer, and they lose more heat per square foot than the wall around them. Over decades of heating and cooling, the operational account has usually been the larger of the two. That is the case for choosing on thermal performance first. uPVC helps there, because the frame conducts little heat and its chambered profile is part of how a window reaches a low whole-window U-factor. The energy guide has the detail.

Three cautions keep this honest.

1. The comparison that matters is between two real options. Compare two windows that both suit the project, on both accounts. A frame with lower embodied impact and a worse U-factor can lose over the building's life. The reverse can also be true.
2. Most of a window's weight is glass, not frame. A triple carries more embodied impact than a double in any frame material. The energy it saves has to earn that back.
3. The grid is getting cleaner. As it does, each unit of energy saved avoids less carbon, and the embodied account matters more.

The tool for the embodied side is an Environmental Product Declaration, a third-party verified statement of a product's life-cycle impacts. Ask for one. Where a manufacturer has none, an industry-average declaration for the material may be the closest thing available, and it should be labeled as such.

The fair criticisms.

• Chlorine chemistry. Vinyl chloride, the building block of PVC, is a known carcinogen. The risk is in manufacture and transport, not in the finished window. It falls on workers and on communities near the plants, and it is controlled by regulation, not removed.
• Fire and burning. Burning PVC gives off hydrogen chloride, which is corrosive and irritating. Uncontrolled burning can also form dioxins. On the other side, PVC is hard to ignite and tends to stop burning when the flame is taken away.
• Additives. Lead and cadmium stabilizers are a legacy problem in old profiles, and they follow the material into recycling.
• Fossil feedstock. Less than most plastics, but not none.
• End of life. Until take-back is common here, the low real recycling rate is a fair point against it.
• Restricted lists. Some green building programs and some owners keep lists of restricted materials, and PVC is on several of them. Check the project's requirements before the windows are specified.

The other materials, fairly.

Material	In its favor	The fair criticism
uPVC	Long life, no repainting, low heat conduction	Chlorine chemistry, additives, weak recycling of old windows in North America
Aluminum	Recycles well, with a real scrap market. Strong and slim	New metal takes a great deal of energy to make. Conducts heat, so it relies on thermal breaks
Wood	Renewable, stores carbon, insulates well	Needs its finish maintained. Sourcing should be certified
Fiberglass	Stable, low heat conduction	Cannot be remelted, so recycling routes are limited

No frame material is clean on every count. Compare whole-life figures for the actual windows being considered, and weigh them with service life, maintenance and thermal performance.

Certified thermal ratings for every Vistaza type and glass are on the energy page. For the parts of a window that set those ratings, start with the energy guide.