Multi-Layer Thermal Insulation with Fibrous Vapour Barrier
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Solution Overview
Problem
Existing insulation materials, particularly multi-layer thermal insulation, lack sufficient water vapour permeability and thermal efficiency to effectively upgrade the energy performance of existing buildings from the outside, leading to issues like condensation and increased energy consumption.
Innovation Solution
A water vapour permeable multi-layer thermal insulation is developed, utilizing air-open fibrous materials with a mean flow pore size of 1 to 20 μm as inner separating layers, which allow water vapour passage while restricting mass air movement, thereby enhancing both water vapour permeability and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multi-layer thermal insulation uses water vapour impermeable materials like aluminium foil or aluminised polypropylene film, then thermal resistance is improved, but water vapour permeability deteriorates
Solution Approach 1:
The insulation is divided into multiple alternating layers: water vapour impermeable reflective layers (aluminium foil or aluminised polypropylene film) and water vapour permeable spacer layers (fibrous wadding or air impermeable material). This segmentation allows each layer type to perform its specialized function - the reflective layers provide thermal resistance while the spacer layers provide water vapour permeability paths, resolving the contradiction between thermal performance and vapour transmission.
Solution Approach 2:
The invention creates a composite multi-layer structure combining materials with opposing properties: water vapour impermeable reflective films alternating with water vapour permeable spacer materials. This composite structure achieves both high thermal resistance (from the reflective layers) and adequate water vapour permeability (from the spacer layers), allowing the insulation to simultaneously improve thermal performance while preventing condensation issues.
2Reliability
If glass wool is used for insulation, then water vapour permeability is improved, but thermal efficiency deteriorates
Solution Approach 1:
The invention combines water vapour permeable fibrous wadding (which allows vapour transmission) with water vapour impermeable reflective films (which provide thermal resistance). The composite structure achieves thermal efficiency comparable to or better than solid foam insulation while maintaining high water vapour permeability, eliminating the need to choose between the two properties.
Solution Approach 2:
The insulation system segments the functions of vapour transmission and thermal reflection into separate alternating layers. The fibrous wadding layers handle vapour permeability while the reflective film layers handle thermal resistance, allowing the system to outperform single-material solutions like glass wool in both thermal efficiency and vapour permeability.
3Temperature
If insulation thickness is increased to improve thermal resistance, then thermal efficiency is improved, but structural complexity and space requirements worsen
Solution Approach 1:
The multi-layer composite structure achieves high thermal resistance (R values of 1.40 to 2.00 m²K/W) in a relatively thin profile compared to traditional fibrous insulation. The alternating reflective and spacer layers create multiple thermal barriers and reflection interfaces, providing superior thermal performance per unit thickness, thereby reducing overall insulation thickness requirements and simplifying installation.
Solution Approach 2:
The invention adds the dimension of reflection (radiant heat barrier) to the traditional conduction-based insulation approach. By incorporating reflective films that block radiant heat transfer, the system achieves higher thermal resistance without proportionally increasing thickness, effectively utilizing a different heat transfer mechanism to improve performance.
4Reliability
If artificial ventilation is installed to remove water vapour, then water vapour control is improved, but energy consumption worsens
Solution Approach 1:
The water vapour permeable spacer layers enable the insulation to self-regulate moisture by allowing passive vapour diffusion through the structure. This eliminates the need for active mechanical ventilation systems, reducing energy consumption while maintaining effective water vapour control through the material's inherent permeability properties.
Solution Approach 2:
The water vapour permeable spacer layers act as intermediaries that facilitate passive vapour transmission through the insulation structure. These layers mediate moisture control without requiring external energy input, allowing vapour to naturally diffuse from high to low concentration areas while the reflective layers prevent condensation.
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 solution achieves high water vapour permeability, with a moisture vapour transmission rate of at least 1,200 g/m²day, and high thermal resistance, with R values ranging from 1.40 to 2.00 m²K/W, effectively preventing condensation and improving energy efficiency.
Implementation Method 1
inner layer of an air-open fibrous material which has a mean flow pore size that allows water vapour to move from one side of the inner layer to the other
Implementation Method 2
water vapour permeable multi-layer thermal insulation including at least one inner layer of an air-open fibrous material
Implementation Method 3
restricts mass movement of air from one side to the other of the inner layer to form a barrier to convection
Data Source
AI summary
A water vapor permeable multi-layer thermal insulation (10) includes two water vapor permeable outer layers (16, 18) encapsulating inner air and water vapor permeable layers (14) of insulation material and at least one inner separating layer (12) of an air-open fibrous material interleaved with the inner thermal insulation layers (14) and having a mean flow pore size that allows water vapor to move from one side of the at least one inner fibrous separating layer to the other and through the inner insulation layers yet restricts mass movement of air from one side to the other of the at least one inner fibrous separating layer (12) to form a barrier to convection.