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
Frequently Asked Questions
What is the thermal break in aluminium joinery and why is it needed?
The thermal break is a glass-fibre-reinforced polyamide 6.6 insert pressed between the two halves of the aluminium profile. It stops temperature transfer, eliminates condensation on the frame and enables nZEB compliance. Without it, aluminium conducts heat ~200 times better than PVC.
What is the difference between aluminium with and without a thermal break?
Aluminium without a break has Uf 5.5-7.0 W/m²K and frequent frame condensation — suitable only indoors. With a 34 mm break, Uf drops to 2.0-2.5; with a 52 mm break it reaches 1.3-1.6 W/m²K and allows nZEB and passive-house certification.
Which Alumil system has the best thermal performance?
Alumil Supreme SF85, with a 34 mm polyamide, Kooltherm inserts and insulating foam, reaches Uf = 1.6 W/m²K and Uw = 0.95-1.1 W/m²K with triple glazing. It has 85 mm depth, RC2 anti-burglary, Passive House Institute certification and all RAL colours.
Can aluminium without a thermal break be used outdoors?
It is not recommended. 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. Outdoors it causes condensation and large heat loss.
Looking for aluminium doors in Sector 1 Bucharest? Complete guide 2026: Alumil systems, th…
Read →Aluminium JoineryWhere can I order aluminium doors in Sector 1 Bucharest? Complete guide 2026Looking for aluminium doors in Sector 1 Bucharest — for a villa, new block, office or comm…
Read →nZEB SystemsWhat Windows Should You Choose for an nZEB House in Romania? Complete Guide 2026Complete technical guide for nZEB windows in Romania 2026: mandatory minimum values, recom…
Read →