Plastics fact sheet - Domestic windows

PVC-U frame windows

Wood frame windows

Aluminium frame windows

What’s it made of?

Glazing, PVC- u frame, steel reinforcement, steel/stainless steel/aluminium (hinges and locks)

Glazing, Softwood or FSC certified hardwood frame, paint, glues, dowels, filler, wrapping foil, rubbers, steel/stainless steel/aluminium (hinges and locks)

Glazing, aluminium frame, polyamide thermal break, polyester powder paint, steel/stainless steel/aluminium (hinges and locks)

Plastic content

55%-65% of frame can be plastic, with other % made up of steel reinforcement, fittings etc (frame can make up 22.9%-28.2% of total window)

<1%

8-17% (of frame) can be plastic; the total frame makes up around 20% of total window

Where is plastic used?

Frame profiles are PVC-U, and can be reinforced with polyurethane foam or glass fibre extruded into the PVC-U material. The surface of frames can be laminated with PVC foil, coated with PMMA (polymethyl metha acrylate) or painted. Seals can be made from plasticised PVC, EPDM (ethylene propylene diene monomers) or TPE (thermoplastic elastomers)

Potentially in glues and paints, as well as trickle vents and small parts of hardware like stops on friction hinges and locking systems.

Plastic used for thermal breaks, and use of polyester powder paint to coat the aluminium profiles

Embodied carbon

Research suggests that the lowest embodied carbon option 52kg CO₂e per m²[1]

Research suggests that the lowest embodied carbon option is 40kg CO₂e per m₂ of double-glazing[2]

14-24% reduction of the embodied impacts of PVC windows[3]

Research suggests that the lowest embodied carbon option is 76kg CO₂e per m2[4], 29-49% increase in embodied impacts of PVC windows[5]

Recycled content

 Up to 40%

 0%

 Up to 50%

Waste management

The RecoVinyl scheme has been set up to co-ordinate the collection and recycling of post-consumer PVC building products. PVC-U can be shredded and compressed into pellets. This recycled 73,700 tonnes of PVC from window profiles in 2018. [6]

There are concerns with legacy additives and work ongoing on the restriction of lead

Timber can also be recycled or used as biomass for energy recovery.

Aluminium will be sent to metal recyclers where it will be sorted into alloy grades which allow it to be recycled into specific product types. The aluminium is re-melted in the smelter. Aluminium has high recycling rates, which can be between 92% and 98% for architectural aluminium

Cost

Average price for new windows (per casement window) -£600-£1800[7]

50% more than PVC-u[8]

25% more than PVC-u[9]

Life span

18-30 years[10] [11]

25-65 years[12], typically 55-65, up to more than 3.5 times than PVC-U[13]

25-80 years[14], typically 45 years[15]

Maintenance period

6 months cycles of cleaning with solvents[16]

Painting every 5 years and staining every 3 years[17]

20 years for re powder coating. Windows should be wiped clean every 6 months[18]

Thermal performance

Thermal conductivity is excellent thanks to the low conductivity of the polymers; however, PVC-U windows rely on a metal frame inside for rigidity, and this can cause the thermal conductance to rise[19]

Thermal conductivity is the lowest among the three materials[20]

Thermal conductivity is poor, the highest of the three materials; however, the implementation of thermal breaks can decrease its thermal conductivity and reduce thermal bridges[21]

Benefits

Low initial cost

Easily installed

Lowest embodied carbon option

Usually high quality

Long life span

High level of recycling (up to 95%)

Little maintenance required

Drawbacks

High plastic content

Relatively short lifespan (18-30 years)

Low level of recycling- 3%

Higher cost than typical PVC-U window

Wood frames are the most demanding in terms of maintenance

High embodied carbon