uPVC or aluminium windows? For ordinary windows in a house, choose uPVC: at the same size it costs less, and the warmest profiles reach a Uw of 0.73 W/(m²K). Choose aluminium when uPVC is not enough: floor-to-ceiling glazing, wide lift and slide doors, slim frames or a specific RAL colour. The table below helps you decide for your own home.
uPVC or aluminium windows: comparison table
| Criterion | uPVC | Aluminium (Aluprof) | |---|---|---| | Insulation, Uw of the whole window | from 0.73 (Kömmerling 88 MD), from 0.75 (Salamander bluEvolution 82) | from 0.95 (MB-79N); MB-104 is the system for passive houses | | Price at the same size | lower | higher | | Large glazing | up to the limits of the profile | floor-to-ceiling windows, corners without a post (MB-86) | | Frame width | wider | slimmer, more glass in the same opening | | Colour | white as standard; foil outside with white inside, or the same colour on both sides | any RAL colour, always the same on both sides | | Sliding doors | tilt and slide (PSK) and lift and slide (HST); coloured PSK doors have a smaller maximum width than white ones | large, heavy lift and slide doors | | Maintenance | wipe the seals, adjust and lubricate the hardware once a year | the same | | Unheated rooms | not relevant | MB-45 without a thermal break, only for interior partitions and unheated conservatories |
uPVC profiles are 76–88 mm deep. MD versions have a third, central seal, so they resist wind and driving rain better and reduce noise. In aluminium, a thermal break between the outer and inner part of the profile keeps the heat in. Without it (MB-45), a window is only suitable for unheated spaces.
When is uPVC enough?
- You are replacing windows in a house or flat, and the openings are a normal size.
- You are on a budget and want the best insulation for the money.
- You are building an energy-efficient house. 82–88 mm profiles with triple glazing give the lowest Uw values we offer.
- You want woodgrain, anthracite or grey windows. On uPVC the colour is a foil from the profile brand's range (VEKA, Kömmerling, Salamander, Gealan).
When is aluminium the better choice?
- You are planning floor-to-ceiling glazing or a corner without a post. That is what Aluprof MB-86 (ST, SI, AERO) is for.
- You need lift and slide doors for a wide patio opening.
- You want a slim frame and as much glass as possible.
- You have a specific RAL colour in mind, for example to match the facade. Powder coating can be any shade, but always the same inside and out.
- You are building a passive house with large glazing. Then look at MB-104.
We cover large windows and sliding doors in more detail in our article on fixed glazing, corner windows and sliding doors.
The middle ground: uPVC with aluminium cladding
Kömmerling 76 MD AluClip and 88 MD AluClip have a uPVC profile inside and aluminium cladding on the facade side. Insulation and price stay closer to uPVC, while from the outside you see an aluminium surface. It is a good option if you like the look of aluminium but your windows are a normal size.
What do we check before we send a quote?
We have worked with windows since 1997 and have completed more than 5,000 orders. For every enquiry we check that each window can be made in the chosen material and system. An opening sash must be at least 450 mm wide, and a door leaf can be at most 2300 mm high (a taller opening gets a fanlight). If uPVC cannot handle a size, we tell you straight away. If a cheaper system will do the job, we tell you that too.
Whatever the material, we do not offer installation. You fit the windows yourself or with a fitter you choose and pay separately. For a detailed comparison of both materials in figures, read uPVC or aluminium.
Price both versions with your own sizes
The simplest way to decide is in the window configurator: build the same project in uPVC first, then in aluminium, and compare the prices, which you see straight away. The systems are described on our uPVC windows and aluminium windows pages. We prepare a quote including delivery within 3 working days, and production takes 3–8 weeks from payment.