Blog 10. Part 2

What is a Thermal Break?

The example shown here is from a box section of extruded aluminum used in a large hinged access Aluminum Clad Wood & uPVC Doors and Windows. The large cavity in the base frame is to allow the manufacturer to fit in all of the various mechanisms and electronics involved to operate the unit, thus the framework has to be fairly large. Without having thermal breaks installed it is highly likely that condensation would form on the inside of the frame due to its large surface area.

Polyamide thermal break which is designed to be slotted directly into the aluminum extrusion and then rolled together to maintain strength, effectively separating the internal section of the metal frame from the external. In this respect the thermal break also forms part of the physical structure of the doors & windows profile.


The polyamide thermal break prevents heat loss by conduction through the frame. However, convection and radiation are also methods by which heat can be transferred; therefore the cavity between the two polyamide thermal breaks is filled with PIR foam insulation to prevent both radiated and convicted heat transfer between the inner and outer metal profiles. This effectively maximizes thermal efficiency. Silicone bubble seals which are used to make the frame airtight, as a poor seal between the fixed and opening elements will also contribute to heat loss from the building.


During the design process, manufacturers should be able to test the effectiveness of their designs using thermal modeling software. This demonstrates the behavior of the architectural glass facade and its thermal performance before incurring significant tooling costs.