Variable Vapor Barrier for Building Moisture Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vapor barriers, such as polyethylene films, are effective in preventing moisture condensation during cold and dry conditions but increase the likelihood of condensation during hot and humid conditions, and fail to facilitate drying in wall cavities when exposed to uncontrolled moisture events.
Innovation Solution
A variable vapor barrier material with a moisture permeance that changes based on ambient humidity, composed of E/X/Y copolymers, organic acids, and optional ethylene- or propylene-containing polymers, allowing for low permeance at low humidity and high permeance at high humidity, forming a monolithic membrane that is waterproof and vapor-permeable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional vapor barrier such as polyethylene film is used to prevent moisture diffusion during cold and dry conditions, then moisture condensation is reduced in the interior wall cavity space, but moisture condensation likelihood increases during hot and humid conditions when moisture flow is from outside to inside
Solution Approach 1:
The vapor barrier material dynamically changes its permeance properties in response to ambient humidity conditions. The material transitions from a low-permeance state during cold, dry winter conditions to a high-permeance state during hot, humid summer conditions, allowing it to adapt its function to match changing environmental requirements and prevent condensation across different seasons
Solution Approach 2:
The physical or chemical parameters of the vapor barrier material change in response to humidity variations. Specifically, the material's permeance parameter increases with ambient humidity, enabling it to maintain appropriate moisture blocking properties during cold conditions while becoming more permeable during hot, humid conditions to prevent interior condensation
2Reliability
If a vapor barrier is installed to control moisture flow from interior to exterior during winter, then moisture condensation is prevented, but the barrier fails to facilitate drying during uncontrolled moisture events like water leaks into the wall cavity
Solution Approach 1:
The vapor barrier dynamically responds to different moisture scenarios by changing its permeance. During normal winter conditions, it maintains low permeance to prevent condensation. During uncontrolled moisture events like water leaks, the material transitions to high permeance states, facilitating rapid drying of the wall cavity by allowing moisture to flow outward through the barrier
Solution Approach 2:
The vapor barrier material autonomously adjusts its permeance properties based on ambient humidity conditions without requiring external control systems. When humidity increases due to moisture events, the material automatically becomes more permeable to facilitate drying, and when humidity decreases, it automatically returns to a low-permeance state to prevent condensation
3Reliability
If a vapor barrier with low moisture permeance is used to block vapor diffusion, then moisture condensation is prevented during cold conditions, but vapor permeation is blocked during hot and humid conditions where moisture flow is from outside to inside
Solution Approach 1:
The vapor barrier's permeance parameter changes in response to ambient humidity. During cold, dry conditions, the material maintains low permeance to effectively block vapor diffusion from the interior. During hot, humid conditions, the material's permeance parameter increases, allowing vapor to pass through and preventing condensation on the interior side of the insulation
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 variable vapor barrier effectively prevents moisture diffusion in dry conditions while allowing vapor permeation in humid conditions, facilitating drying and maintaining insulation performance, reducing the risk of moisture-related damage in buildings.
Implementation Method 1
a variable vapor barrier for moisture control of buildings formed from a material or composition having a moisture permeance of less than 0.1 perms (grains/h·ft2·inches of Hg) at less than 50% average humidity... and a moisture permeance greater than 4, or greater than 10 perms, at greater than 60% average humidity
Data Source
AI summary
Disclosed is a variable vapor barrier for moisture control of buildings comprising or formed from a material having a moisture permeance of less than 0.1 perms (grains/h·ft2·inches of Hg) at less than 50% average humidity, such as from 10 to 50% or 20 to 40%; and a moisture permeance greater than 4, or greater than 10 perms at greater than 60% average humidity, such as from 60 to 90%, or 70 to 80%. Also disclosed are articles comprising the variable vapor barrier and methods of their use.