Declaration of Performance (DoP) and CE Marking: How to Read Them
What the DoP and CE marking mean for windows and doors under EN 14351-1, which values they contain and why you should request them before ordering.
Standards and documents
What Is a Thermal Break in Aluminium Profiles?
How it works
The profile is split into two aluminium parts, an inner and an outer one, joined by an insulating element with low conductivity. This break stops heat from passing straight through the metal, reducing the thermal bridge in the frame.
Why it matters
- Better insulation than plain aluminium.
- Lower condensation risk on the frame: see why windows sweat.
- More comfort, because the inner frame doesn’t get as cold or as hot.
When plain aluminium is enough
Plain aluminium (without a thermal break) is used for fixed panels and partitions, including mirrored double glazing. For windows, balcony doors and entrance doors that separate the heated space from the outside, thermally broken aluminium is chosen.
How to verify
- ask for the Uw value in the system’s Declaration of Performance;
- compare the system and glass being offered, not just the profile;
- ask for installation with perimeter insulation: see installation in 8 steps.
How to compare two aluminium windows
- Compare the Uw from each system’s DoP.
- Compare the glass included in the quote.
- Ask about the system depth and whether the profile has a thermal break.
- Ask about installation: perimeter insulation determines the real result.
Frequently asked questions
Is thermally broken aluminium suitable for winter?
Yes, when the system and glass are chosen well and installation is good. Concrete values are given in the Declaration of Performance.
How does it differ from uPVC?
Both can insulate well; aluminium allows slimmer profiles and larger openings. Read our detailed uPVC vs aluminium comparison.
Can you see the thermal break from outside?
No. It shows only in the profile cross-section and in the Uw value of the Declaration of Performance.
Do facades have a thermal break?
Curtain wall facades are insulated aluminium structures, according to the selected system.
