The 34 mm polyamide thermal break physically separates the inside from the outside of the aluminium profile, eliminating the thermal bridge and bringing Uw down to 0.95–1.3 W/m²K. Complete guide: which Alumil Supreme and Smartia systems we recommend, how to choose between 34 mm vs 52 mm break, and what prices to expect in 2026.
What is a thermal break and why does it matter for aluminium
Pure aluminium conducts heat ~200 times better than PVC. Without any treatment, an aluminium profile would become a cold radiator in winter and a heat collector in summer — the exact opposite of what you want from a modern window.
The thermal break solves this problem fundamentally. It is a 6.6 polyamide insert reinforced with glass fibre, cast or pressed between the two halves of the aluminium profile. This:
- Stops heat transfer between inside and outside
- Eliminates condensation on the window frame
- Reduces building heat losses
- Enables nZEB and passive house certifications
Without a thermal break, aluminium is suitable only indoors — partitions, showrooms, garages — where the temperature difference between the two faces of the profile is not significant.
With vs without thermal break: direct comparison
| Feature | Aluminium without break | Aluminium with 34 mm break | Aluminium with 52 mm break |
|---|---|---|---|
| Uf profile (W/m²K) | 5.5–7.0 | 2.0–2.5 | 1.3–1.6 |
| Uw complete window | 3.5–5.0 | 1.4–1.8 | 0.95–1.2 |
| Condensation on frame | Frequent | Absent | Absent |
| Exterior use | No | Yes | Yes, including passive houses |
| nZEB certification | No | Possible with triple glazing | Yes |
| Relative cost | Low | Medium | Premium |
Alumil systems available at Neofort BIZ
Alumil Supreme SF85 — maximum performance
34 mm polyamide with Kooltherm inserts and insulating foam. Uf = 1.6 W/m²K, Uw = 0.95–1.1 W/m²K with triple glazing 4-16-4-16-4.
Technical specifications:
- Profile depth: 85 mm
- Gaskets: 3 rows co-extruded EPDM
- Hardware: 4-point locking, RC2 burglar resistance
- Maximum glazing: 52 mm (triple Low-E possible)
- Colours: all RAL colours + wood effect via electrostatic painting
- Certified by Passive House Institute (PHI)
Recommended for: premium homes, modern villas, nZEB projects, renovations with high energy requirements.
Alumil Smartia S67 — optimal value for money
Standard 34 mm polyamide. Uf = 2.0 W/m²K, Uw = 1.2–1.4 W/m²K.
Technical specifications:
- Profile depth: 67 mm
- Gaskets: 2 EPDM rows
- Hardware: 4-point locking
- Maximum glazing: 40 mm (double Low-E)
- Colours: complete RAL catalogue
Recommended for: apartment buildings, offices, commercial spaces, medium-to-high budget projects.
Alumil Smartia S350 — sliding systems
Tilt-and-slide and lift-and-slide system with thermal break. Ideal for terraces and living rooms with large exterior openings.
- Openings up to 4.5 m width per panel
- Uw = 1.2 W/m²K
- RC2 anti-burglary hardware
How to choose between 34 mm and 52 mm polyamide
Choose 34 mm (Smartia S67) if:
- You have a reasonable budget and want good performance
- You are building or renovating a standard home
- You have no nZEB or passive house certification requirements
Choose 52 mm (Supreme SF85) if:
- You are building an nZEB or passive house
- Your designer has specified Uw < 1.0 W/m²K
- You want to completely eliminate condensation and thermal bridges
- You have large windows (> 2 m²) where heat loss matters significantly
Installation matters as much as the profile
The best thermal break window becomes useless if installed incorrectly. At Neofort BIZ we always use:
- Blaugelb Triotherm+ precasings — eliminate the thermal bridge at the installation zone
- Pre-compressed tape on the outside — wind and water sealing
- Anti-vapour tape on the inside — vapour diffusion barrier
- Warm Edge spacers in the glass — eliminate thermal bridge at glazing perimeter
Without these 4 elements, nZEB certification is not possible, regardless of the profile quality.
Request a quote for Alumil aluminium windows
Send us your dimensions and opening types and we will reply with a complete quote within 48 hours.
WhatsApp: +40 752 443 435
Hours: Monday–Friday, 10:00–18:00
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