uPVC vs. Aluminium windows
Energy efficiency: how do they compare?
uPVC is a natural insulator. The multi-chambered frame design traps air within the profile, creating an effective barrier against heat loss without requiring any additional technology. For north-facing rooms or properties in exposed locations where heat retention is the priority, uPVC offers the most exceptional levels of thermal efficiency.
Aluminium is naturally thermally conductive, which means the metal itself will transfer heat. However, modern thermal break technology has closed this gap considerably.
In reality, you cannot quite achieve the same exceptional level of energy efficiency from an aluminium window as you can from a triple-glazed uPVC window. However, for many homeowners the energy performance of modern aluminium is more than sufficient.
Modern aluminium windows and uPVC windows from Everest will comfortably beat the requirements of current building regulations and will significantly reduce your heating bills compared to older or single-glazed windows.
Strength and durability
This is where aluminium has a clear and significant advantage. Aluminium is one of the strongest frame materials on the market and the frame can support large panels of glass for an unobstructed view.
Aluminium has a lifespan that typically exceeds 40 years. It will not rust, rot, swell, warp or deteriorate, and the powder-coated finish remains stable even in intense sunlight. The frames maintain their shape and operation smoothly for their entire lifetime, with no risk of bowing, flexing or sagging.
uPVC windows have a typical lifespan of 20 to 25 years, though quality uPVC can last longer with proper care.
Similar to aluminium, uPVC will not rot, rust or flake, and it requires no painting, but it can become discoloured over time, particularly in white finishes exposed to UV light.
Over extended periods, uPVC can also become more brittle, and the frames may begin to bow in very large window openings where the material is under greater structural stress.
Both materials are weatherproof, but for coastal locations where windows face increased exposure to corrosive salt water, it is important to note that standard aluminium frames may require a marine-grade finish. Everest don't offer marine-grade aluminium and can't guarantee their frames within five miles of a coastal area. uPVC performs well in coastal conditions without any special treatment, which gives it an advantage in seaside locations.
If long-term durability and structural strength are your priority, aluminium is the superior material (in non coastal conditions).
Design and appearance
The most immediately visible difference between uPVC and aluminium windows is the frame profile.
Aluminium's strength allows for sleek, slimline frames, which means more glass, more light and cleaner views from inside. This is the defining aesthetic appeal of aluminium and the reason it is the preferred choice for contemporary homes, architect-designed properties and large window installations where you want to maximise the sense of space and openness.
uPVC frames are necessarily thicker because the material is less strong than metal and requires more bulk to achieve the same structural integrity. This is not a problem in most standard window sizes, but in larger openings the difference in frame thickness becomes more noticeable.
For traditional properties, the slightly more substantial uPVC frame can actually complement the architectural style, particularly in sash windows or casement windows with Georgian bars.
Both aluminium and uPVC are available in a variety of colours. uPVC also has the option of woodgrain foils for timber effect in country properties.
White remains the most popular colour for uPVC, with grey also being a widely popular choice. Aluminium suits dark grey and black for a striking contemporary finish. Both frame materials are available in a dual-colour finish for inside and outside contrast.
Note that dark uPVC coloured frames are reinforced as they are more likely to bow. For this reason, in double glazing, only white and cream coloured frames can achieve the A+ energy ratings. In triple glazing, all colours achieve an A+ rating.
Maintenance
uPVC and aluminium windows are low-maintenance options that require no painting, staining or varnishing. A periodic wipe down with warm soapy water is all that is needed to keep either material looking clean and fresh.
Security
Both uPVC and aluminium windows offer excellent security when manufactured and installed to a high standard. The security of a window depends as much on the locking system, hinges and glazing specification as it does on the frame material itself.
That said, aluminium's inherent strength does provide a structural advantage. The rigidity of the metal means it is extremely difficult to bend, flex or force, which adds an extra layer of resistance against physical attack. This makes aluminium particularly suitable for ground-floor windows or windows in more exposed positions.
uPVC windows are reinforced internally with galvanised steel, and when fitted with multi-point locking systems, they provide a high level of protection.
For most residential properties, both materials provide more than adequate security. If you want the strongest possible frame material, aluminium has the edge, but a well-specified uPVC window with proper locks and quality hardware is highly secure in its own right.
Cost: what should you expect to pay?
uPVC windows are the most economical option, with aluminium being around 25% more expensive. The lower manufacturing cost of uPVC, combined with faster and simpler installation, makes it the more affordable option, particularly for larger projects where multiple windows are being replaced at once.
Aluminium windows carry a higher upfront cost that reflects the material, the manufacturing process and the broader range of colour and finish options available. However, the longer lifespan of aluminium, often exceeding 40 years compared to 20 to 25 years for uPVC, means fewer replacements over the lifetime of your property.
For homeowners planning to stay in a home long-term, aluminium can prove more cost-effective despite the higher initial outlay. Read more about how much windows cost.
