Evacuated LDPE Foam House Wrap Thermal Insulation
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Solution Overview
Problem
Conventional house wraps lack superior thermal insulation characteristics and operational efficiency, with existing materials being prone to damage and having inadequate tensile properties, breathability, and moisture vapor transmission rates.
Innovation Solution
A composite house wrap is developed using expanded low-density polyethylene foam with evacuated closed cells, formed by mixing low-density polyethylene pellets with glycerides and a primary blowing agent, followed by curing to dissipate at least 80% of the blowing agent, creating a breathable and durable barrier with enhanced thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional house wrap materials are used, then cost-effectiveness and ease of handling are maintained, but thermal insulation performance is insufficient
Solution Approach 1:
The patent employs composite materials by combining polyethylene foam with breathable membrane layers to create a multi-functional house wrap system. This composite structure integrates thermal insulation (foam layer) with moisture vapor transmission capabilities (breathable membrane), resolving the contradiction between improving thermal insulation and maintaining ease of manufacture by consolidating multiple functions into a single integrated product.
Solution Approach 2:
The patent applies local quality by creating distinct zones within the house wrap structure with different properties: the polyethylene foam provides thermal insulation in specific regions, while the breathable membrane layers handle moisture vapor transmission. This localized functional differentiation allows the material to achieve superior thermal insulation without requiring the entire structure to be complex, maintaining ease of manufacture through specialized zone design.
2Strength
If conventional house wrap materials are used, then ease of handling is maintained, but tensile properties and durability are inadequate
Solution Approach 1:
The patent uses composite materials combining polyethylene foam with breathable membrane layers to achieve enhanced tensile properties. The foam structure provides structural strength and tear resistance, while the membrane layers contribute to overall durability. This composite approach improves strength without significantly compromising ease of handling, as the foam core maintains flexibility and workability during installation.
Solution Approach 2:
The patent applies segmentation by dividing the house wrap into distinct functional layers: the polyethylene foam core provides structural strength and durability, while separate breathable membrane layers handle moisture vapor transmission. This segmented structure allows each layer to be optimized for its specific function, improving overall tensile properties and durability while maintaining ease of handling through modular construction.
3Quantity of substance
If conventional house wrap materials are used, then breathability is maintained, but moisture vapor transmission rate is insufficient
Solution Approach 1:
The patent employs composite materials by integrating breathable membrane layers with polyethylene foam structure. The breathable membranes are specifically designed to allow moisture vapor transmission while the foam structure provides thermal insulation. This composite approach increases moisture vapor transmission rate without requiring excessive structural complexity, as the membrane-foam integration consolidates multiple functions into a unified system.
Solution Approach 2:
The patent utilizes porous materials by incorporating breathable membrane layers with controlled porosity that enable moisture vapor transmission. These porous structures allow water vapor molecules to pass through while maintaining the structural integrity needed for building envelope applications. This approach effectively increases moisture vapor transmission rate without adding significant structural complexity, as the porosity is inherent to the membrane material design.
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 composite house wrap provides improved thermal insulation with an R-value of at least R-6, maintaining cost-effectiveness and ease of handling while offering superior barrier protection and moisture vapor transmission.
Implementation Method 1
The composite house wrap provides improved thermal insulation with an R-value of at least R-6
Implementation Method 2
having tortuous paths of thermal conductivity
Implementation Method 3
expanded low-density polyethylene foam with evacuated closed cells
Implementation Method 4
adding a primary blowing agent comprising one of liquid propane, liquid butane, and combinations thereof, to the mixture and gasifying the blowing agent to expand the low density polyethylene
Implementation Method 5
curing the expanded low density polyethylene until 80%, preferably at least 95% and more, preferably at least 99% or more of the primary blowing agent is dissipated from cells within the expanded low density polyethylene
Data Source
AI summary
A house wrap for a building comprises a reinforcing drainage plane layer configured to face the outside of the building; a breathable, non-perforated barrier film bonded to the drainage plane layer; and at least one insulating layer including a perforated expanded low density polyethylene foam layer, wherein in the expanded low density polyethylene layer at least 80% of the blowing agents are dissipated from closed cells within the expanded low density polyethylene layer, forming evacuated closed cells whereby a partial vacuum is formed within the closed cells of the low density polyethylene layer.