Organic Insulating Forms for Passive House Curtain Walls
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Solution Overview
Problem
Curtain wall systems face challenges in achieving effective thermal separation and air-tightness, leading to issues like condensation, thermal bridging, and increased energy consumption, which are exacerbated by thermal bridging and air leakage, making it difficult to meet the Passive House standard for energy efficiency and comfort.
Innovation Solution
A unitized curtain wall system with pre-assembled, pre-glazed aluminum framed units and organic shaped insulating forms that interconnect adjacent panels, providing compressible thermal separation and air movement control, while using advanced sealing components to meet the Passive House certification criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional curtain wall systems are used with standard framing members, then installation is simpler and cost is lower, but thermal bridging occurs and energy efficiency deteriorates
Solution Approach 1:
The patent implements nested thermal insulation within the curtain wall framing by placing continuous rigid insulation boards inside the aluminum frame cavities, and additionally nesting compressible foam insulation within the same cavities to fill gaps and wrap around thermal bridge paths. This multi-layer nested insulation approach blocks thermal transmission through the framing members while maintaining a compact structure.
Solution Approach 2:
The patent uses composite construction by combining different materials with complementary thermal properties: continuous rigid insulation boards (such as polyisocyanurate or poly styrene) are combined with compressible foam insulation (such as polyethylene or rubber foam), and both are integrated with thermally broken aluminum framing members. This composite approach creates a multi-barrier thermal resistance system that significantly reduces thermal bridging.
2Productivity
If unitized curtain wall systems are used for factory assembly, then installation speed and quality consistency improve, but achieving effective air and water seals becomes more challenging
Solution Approach 1:
The patent incorporates pre-compressed foam gaskets and sealants within the factory-assembled curtain wall units before shipment. These compressible sealing elements are positioned at all joint interfaces and penetration points to accommodate dimensional tolerances and structural movements that occur during installation, ensuring reliable air and water seals are maintained despite the challenges of field assembly.
Solution Approach 2:
The patent uses flexible membrane weather barriers and liquid-applied sealants as thin film layers within the curtain wall assembly. These flexible films conform to the complex geometries of the unitized framing and provide continuous air and water resistance planes that maintain sealing effectiveness despite minor variations in assembly tolerances or building envelope movements.
3Loss of energy
If thermal insulation is increased to meet Passive House standards, then energy efficiency improves, but condensation risk increases due to unfavorable thermal conditions
Solution Approach 1:
The patent introduces a vapor retarder or vapor barrier layer as an intermediary membrane within the curtain wall insulation assembly. This vapor barrier is positioned on the warm side of the insulation to prevent moisture-laden indoor air from penetrating into the cold insulation and condensing. The vapor barrier acts as a mediator that allows thermal insulation to be increased for energy efficiency while simultaneously preventing condensation by blocking moisture migration.
4Strength
If aluminum framing members are used for curtain walls, then structural strength and durability improve, but thermal bridging through the metal frames increases heat transfer
Solution Approach 1:
The patent segments the continuous aluminum framing members by inserting thermal break elements at regular intervals and at connection points. These thermal breaks divide the thermal conduction path into separate segments, forcing heat to travel through multiple insulation barriers rather than continuously through the metal frame. The aluminum framing is segmented into exterior and interior portions connected only through thermally insulating materials.
Solution Approach 2:
The patent introduces thermally insulating intermediary materials between the interior and exterior portions of the aluminum framing members. These intermediaries include rigid insulation boards integrated into the frame cavities, foam injection insulation, and thermally broken connection elements. The intermediaries mediate the thermal transfer by providing high thermal resistance paths that significantly reduce heat conduction through the structurally strong aluminum frames.
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 achieves significant energy efficiency, reducing thermal transmission rates and maintaining healthy indoor humidity levels, thereby enhancing occupant comfort and reducing energy costs, with the PHACTOR II system being the first aluminum curtain wall system certified to the Passive House standard worldwide.
Implementation Method 1
Organic shaped insulating forms are disposed laterally between top and bottom horizontal rail components of adjacent curtain wall panels
Implementation Method 2
The forms are compressible to permit flexing vertical movement of the curtain wall units while reducing air movement in a horizontal cavity formed between the top and bottom horizontal rail components
Data Source
AI summary
A unitized curtain wall system includes pre-assembled, pre-glazed aluminum framed curtain wall units. Vertical mullion components and top and bottom horizontal rail components interconnect adjacent curtain wall panels. The curtain wall units are suspended from one or more upper anchors installed on an upper floor slab. The bottom horizontal rail components are engaged with top horizontal rail components of adjacent, lower curtain wall units forming a continuous beam scheme for vertical mullion components and configured to accept lateral loads. The gravity loads of curtain wall units are supported by one or more floor anchors. Organic shaped insulating forms are disposed laterally between top and bottom horizontal rail components of adjacent curtain wall panels. The forms are compressible to permit flexing vertical movement of the curtain wall units while reducing air movement in a horizontal cavity formed between the top and bottom horizontal rail components forming a stack joint.