Thermally Broken Fenestration Frames for Bi-Metallic Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aluminum fenestration systems experience the bi-metallic effect, where exterior and interior extrusions expand differently due to temperature differences, causing interference with frames and difficulty in opening/closing doors or windows.
Innovation Solution
A fenestration system with a central extrusion and thermal breaks, using retainer clips and thermal barriers to couple exterior and interior extrusions, along with insulators to mitigate thermal conduction and reduce temperature differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum is used for exterior and interior extrusions, then structural longevity and corrosion resistance are improved, but thermal conduction increases causing the bi-metallic effect
Solution Approach 1:
The aluminum fenestration system is divided into separate exterior and interior extrusions that are thermally decoupled. Thermal breaks (insulating barriers) are inserted between the exterior and interior aluminum components, segmenting the thermal path while maintaining structural continuity. This allows each aluminum extrusion to maintain its structural integrity while preventing heat transfer between them.
Solution Approach 2:
Thermal break materials serve as intermediary elements between the exterior and interior aluminum extrusions. These thermal breaks act as mediators that physically connect the two aluminum components structurally while thermally isolating them, preventing the bi-metallic effect without compromising the structural longevity of the aluminum framework.
2Loss of energy
If thermal breaks are added to reduce thermal conduction, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The thermal break components are merged with the extrusion assembly as integrated units. Rather than adding separate, complex thermal isolation systems, the thermal breaks are incorporated into the extrusion design itself, creating a unified structure that provides both structural support and thermal isolation in a single assembly.
Solution Approach 2:
The thermal breaks serve multiple functions simultaneously: they provide thermal isolation to reduce energy transfer, maintain structural connectivity between exterior and interior extrusions, and prevent the bi-metallic effect. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in system complexity.
3Temperature
If exterior extrusion is heated to elevated temperatures, then thermal radiation from sun is utilized, but bi-metallic effect increases causing interference with door operation
Solution Approach 1:
The thermal expansion problem is extracted and isolated to the exterior extrusion by thermally decoupling it from the interior extrusion. The thermal breaks allow the exterior aluminum to expand and contract freely in response to temperature changes without transmitting these dimensional changes to the interior extrusion and door assembly, thereby maintaining smooth door operation despite high exterior temperatures.
Solution Approach 2:
The thermal isolation changes the thermal parameters of the system by preventing heat transfer from the exterior to the interior extrusion. This parameter change ensures that the interior extrusion and door assembly remain at stable temperatures regardless of exterior temperature fluctuations, maintaining consistent dimensional stability and operational ease.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively reduces thermal conduction and minimizes the bi-metallic effect, enhancing structural integrity and ease of operation by maintaining consistent extrusion lengths.
Implementation Method 1
One disadvantage to the use of aluminum in windows and doors is that it is a highly conductive material. Conduction is heat transfer which can be controlled by the addition of low-conductance thermal barrier materials.
Implementation Method 2
Due to convection and thermal radiation from the sun or warmer ambient temperature in contrast to indoor temperatures, the exterior extrusion can be heated to an elevated temperature, such as 170° F., which causes the exterior extrusion to expand and bow relative to the interior extrusion
Implementation Method 3
an insulator positioned between the exterior extrusion and the central extrusion
Data Source
AI summary
A fenestration is disclosed comprising a plurality of frame members. At least one of the frame members comprises an exterior extrusion, an interior extrusion, a central extrusion intermediate the interior extrusion and the exterior extrusion, and a thermal break to couple the exterior extrusion and the central extrusion.