Thermal break windows: Polyamide technology vs. P&D

thermal break windows example

Aluminum is, in most ways, the perfect material for structural fenestration systems. It is powerful, light, weather-proof, and needs very little maintenance. However, aluminum is also a good conductor of heat. 25%–30% of residential heating and cooling energy used came from heat gain and heat loss through windows. Therefore, manufacturers need a thermal break (Thermal Barrier or Thermal Strut) of aluminum to reduce energy consumption. There are currently two principal types of thermal barriers used for thermal break windows globally: Polyamide Thermal Barrier Strips and Pour & Debridge (P&D).

What are thermal break windows with the Pour and Debridge method?

P&D thermal barriers history started in the 1950s. The polyurethane-based Pour&Debridge (P&D) thermal barrier system was developed in North America. This system uses a two-part polyurethane that manufacturers pour into and cure within a “dog bone” structural cavity in the finished aluminum extrusion. After that, manufacturers condition the cavity surfaces using either the Azo-Brader or the Lancer machinery to limit the metal bridge that acts as a conductor of hot or cold temperatures on the exposed surface.

However, in the 1970s, manufacturers saw that P&D systems had a propensity to shrink, exposing many installed aluminum windows and doors to water penetration. Due to the “dry-shrinkage” problem, some European manufacturers tried to look for alternatives. A unique method for extruding plastics to develop an alternative to the P&D application was developed in Germany. These applications contained Polyamide 66 with 25% glass fiber reinforcement (PA66GF25). 

What are thermal break windows with polyamide technology?

These revolutionary pressure extruded polyamide insulating strips join two separate aluminum extrusions into one thermally broken frame. Manufacturers precisely extrude polyamide thermal barrier profiles to achieve the desired profile shapes and geometries. The process can hold very tight tolerances with extremely repeatable output. Polyamide thermal break has a higher melting point than PVC or polyurethane used in other systems. Since its thermal expansion coefficient is very close to aluminum, the bond between it and the extrusion maintains excellent structural integrity through a wide range of temperature fluctuations.

Polyamide insulating profile provides a true composite assembly that features strong structural integrity. Also, there are no thermal expansion issues due to much closer expansion coefficients between Polyamide and Aluminum. The polyamide strip is a mouldable composite material. Its fibers are oriented in all three dimensions to ensure appropriate strength. As such, manufacturers can use these strips across all types of fenestration, including oversized and impact-resistant systems. Therefore, polyamide thermal barriers are the best for thermal break windows. 

Comparison between P&D and Polyamide Thermal Barriers Thermal Conductivity 

The polyamide profile has almost an IDENTICAL expansion coefficient with aluminum alloy. The composite needs to remain intact over time. Hence, the thermal barrier’s choice and performance play a key role in the structural composite assembly. The aluminum window and door systems must withstand constant wind load and thermal conditions (expansion and contraction). Due to the large difference in expansion coefficient, Thermal Break Windows with P&D will experience thermal shrinkage in some cases. That will lead to possible leakage and loss of composite strength.

Thermal Break Polyamide strips feature elastic composites with strong shear values, no thermal or dry shrinkage, making the thermally broken aluminum systems strong and safe assemblies. Comparing to P&D, extruded polyamide thermal barrier strip provides 2.5 times more separation when the same size is called for.

Thermal Comparison between Polyamide Strips and P&D Polyamide insulating profiles come in various shapes/geometries and widths. Both solid and hollow chamber polyamide strips are available to meet customers’ specific requirements. And the wider the polyamide strips, the better heat, and sound insulation. 

thermal break windows example
Thermal break windows and a comparison between technologies

5 advantages of polyamide technology in thermal break windows

Resistance to heat, humidity, corrosion, and UV radiation

Polyamide Profiles will withstand heat in fenestration systems better than any other system, resulting in improved structural integrity and better thermal break windows. It has good resistance properties; even up to 200° C. Polyamide also absorbs the water contained in the environment’s humidity. Another characteristic is that it is resistant to corrosion and UV radiation due to the polymer and processing method’s intrinsic properties and its carbon black content.

Identical expansion coefficients

The Polyamide struts and the aluminum frames have almost identical coefficients of expansion. As a result, thermal break systems resist thermal cycling, which occurs in actual building conditions better than any method available in today’s market. 

Improving Uf-values

The polyamide struts have the ability to increase the separation between the inside and outside aluminum extrusions. Hence improving thermal insulation or Uf-value. Uf value indicates the amount of heat that passes through a window profile. If your windows have standard aluminum profiles with P&D polyamide, a building may develop condensation or even mold. Besides the resulting high repair costs, household mold also aggravates respiratory problems such as asthma. Therefore, thermal break windows with polyamide struts are the best option to improve thermal insulation. 

Polyamide is a plastic that insulates more than 500 times better than aluminum, so thermal break profiles have a much lower Uf value – and transmit much less heat or cold. As a result, a building stays warmer in winter while keeping the heat outside more easily in summer.

More design possibilities

The use of polyamide strut allows for endless new product designs. With this method, the two separate aluminum extrusions can easily have different paint or anodize a combination, offering unparalleled design flexibility and finish options for each use. 

Different windows with the same aluminum profile

The polyamide has the ability to make various windows and door systems with the same aluminum profiles by merely substituting the polyamide profile. You can use differently sized and shaped polyamide insulating struts to achieve that. 

Both polyamides and P&D are accepted worldwide as the premier choices for thermal protection. Polyamide thermal breaks windows have been in use in Europe for decades. P&D is the main system used for thermal barriers in North America. However, many American organizations support Polyamide thermal barriers as one of the best methods for improving aluminum fenestrations’ energy usage. Polyamide struts will be more and more popular in North America for thermal break windows and door systems. Starlight Corp offers the best thermal break assembly machines for polyamide thermal break insertion for aluminum profiles.