Ask five installers whether uPVC or aluminium windows are better and you will get five different answers, usually shaped by whatever they happen to sell. The truth is that both are good products in 2026, and the right choice depends on your house, your budget and how long you plan to stay. Here is a straight comparison based on what we see fitting both around Dunstable, Houghton Regis, Leighton Buzzard and the villages in between.
uPVC is still the more affordable option. For a typical three bed semi in Dunstable with eight to ten windows, a supply and fit job in white uPVC usually lands somewhere between £5,000 and £8,000. The same house in aluminium tends to sit between £9,000 and £14,000, depending on the system, colour and glazing spec.
That said, the difference is not as wide as it was ten years ago. Coloured or woodgrain uPVC adds 15 to 25 percent to the base price, and once you are into anthracite grey foiled uPVC with slim sightlines, you are not far off an entry level aluminium system. If colour and slim frames are what you are after, it is worth getting both quoted rather than assuming aluminium is out of reach.
Modern uPVC has a natural advantage here because plastic does not conduct heat. A standard uPVC window with double glazing will typically achieve a U value of around 1.2 to 1.4 W/m²K, and triple glazed versions can get down to 0.8. Aluminium used to be the cold option, but thermally broken frames with a polyamide barrier have closed the gap, and a good aluminium window now achieves 1.2 to 1.6 with double glazing.
In practice, the glass unit matters more than the frame material. Ask what the whole window U value is, not just the centre pane figure, and check the frame includes a proper thermal break if you go for aluminium. Both materials will comfortably meet current Building Regulations of 1.4 W/m²K for replacement windows, and a FENSA or CERTASS registered installer will certify the job either way.
This is where aluminium really earns its price. Because it is stronger, the frames can be much slimmer, typically 40 to 60mm compared with 70mm or more for uPVC. On a large picture window or a set of bifolds, that difference is obvious. Aluminium also comes in almost any RAL colour, with the option of a different colour inside and out, and it suits the flat roofed and mid century houses you find around parts of Dunstable and Luton.
uPVC has improved a great deal, and flush sash and mechanically jointed options now do a convincing job of imitating timber on older properties. For a standard semi or terrace with casement windows, most people would struggle to tell the difference from the pavement. Where uPVC still falls short is on very wide openings, where the frames have to bulk up to carry the weight of the glass.
Both need little more than a wipe down and an occasional check of the hinges and seals. A decent uPVC window should give you 20 to 30 years, though cheaper white profiles can discolour slightly and hardware tends to be the first thing to wear. Aluminium, with a powder coated finish, is generally expected to last 40 years or more and is fully recyclable at the end of its life.
On resale, aluminium can add a bit of kerb appeal to a higher value or architect designed home, but on an average Bedfordshire semi you are unlikely to recover the extra cost when you sell. Choose it because you want it, not as an investment.
If you want the best value on a typical family home, uPVC wins on price and thermal performance and is the sensible default for most replacement jobs. If you are extending, fitting large sliding or bifold doors, or you want slim grey frames on a modern looking house, aluminium is worth the extra and will look right for decades.
Plenty of homeowners mix the two: aluminium on the rear extension and bifolds where the big glass is, uPVC on the front and upstairs where nobody looks closely. A good installer should be happy to quote for both without pushing you either way.
Not with modern thermally broken frames. A good aluminium window now sits within a few tenths of a U value of uPVC, and the glass specification makes more difference than the frame material.
Expect to pay roughly 50 to 80 percent more for aluminium on a like for like job, though coloured uPVC and slim profile systems narrow that gap. Always get both quoted for your specific house.
Usually not, as replacing windows falls under permitted development for most houses. The exceptions are listed buildings, flats and conservation areas, where you should check with Central Bedfordshire Council first.
Tell us about your job and we will get back to you the same day to arrange a free, no-obligation survey.