Thermal Break Windows Explained: How PA66GF25 Strips Save Energy.

What is a thermal break?.

A thermal break is an insulating barrier placed between the interior and exterior aluminium profiles of a window or door frame. Without it, aluminium's high thermal conductivity would transfer heat directly through the frame — making the room hot in summer and cold in winter.

Why PA66GF25?.

PA66GF25 stands for Polyamide 66 reinforced with 25% glass fibre. This material was chosen as the industry standard for several reasons:

• Thermal conductivity: 0.3 W/m·K vs aluminium's 160 W/m·K — a 500× reduction
• Structural strength: The 25% glass fibre reinforcement ensures the strip can handle wind loads and operational stress without deforming
• Temperature resistance: Stable from -40°C to +80°C, covering all climate zones
• Durability: Does not degrade, corrode, or lose performance over the lifespan of the window

How much energy does it save?.

A window with PA66GF25 thermal break strips typically achieves a U-value (Uw) of 0.8–1.5 W/m²K, compared to 5.0+ W/m²K for a non-thermally-broken aluminium frame. This translates to:

• Up to 60% reduction in heat loss through the frame
• Lower heating and cooling costs throughout the year
• Compliance with strict energy codes like Australia's NCC Section J, EU's EN 10077, and North America's NFRC ratings

PINDÉ's thermal break approach.

All PINDÉ systems use PA66GF25 thermal break strips as standard. Our flagship A120 Casement Window features a 35.3mm wide strip — one of the widest in the industry — with an integrated full-window rubber seal for dual thermal insulation.

Combined with triple EPDM rubber sealing and triple-glazing capability (up to 130mm), the A120 system delivers exceptional thermal performance for the most demanding climates.

Key takeaway.

When comparing aluminium window systems, always check the thermal break width and material. PA66GF25 is the gold standard — anything less compromises long-term performance. The wider the strip, the better the insulation.