Developing Barrier Layers to Minimize Volatile Emissions from Structural Insulated Panels (SIPs)

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Developing Barrier Layers To Minimize Volatile Emissions From Structural Insulated PanelsJohn C. LittleDepartment of Civil and Environmental EngineeringVirginia TechEva MarandDepartment of Chemical EngineeringVirginia TechThe most common Structural Insulated Panel (SIP) configuration uses oriented strand board (OSB) and expanded polystyrene foam (PSF) in a multi-layer, sandwich-like structure. SIPs have the potential to radically improve the quality, durability, energy efficiency, environmental performance, and affordability of housing. Despite these impressive benefits, degradation of indoor air quality is a negative consequence of using engineered wood products to create tighter building envelopes. For this reason, we will develop and deploy nanocomposite clay/polyurethane barrier layers to significantly reduce, or perhaps even eliminate, emission of volatile organic compounds (VOCs) from SIPs into indoor air. VOC diffusion barriers have never been used in building materials, but the approach holds considerable promise because polyurethanes can be tailored to give a diverse range of products such as foams, coatings, adhesives, rubbers or thermoplastic elastomers. By significantly reducing VOC emissions from SIPs, we will eliminate the primary environmental drawback of an otherwise exceptionally attractive building technology. The ability to understand, predict and consequently minimize the negative impact of SIPs and other building materials on indoor air quality will be extremely valuable. We have demonstrated that emissions of VOCs from several single-layer material systems can be predicted using a mathematical model, and will now employ an analogous fundamental approach to develop and validate a multi-layer model that can be used to predict emissions from SIPs. The model will include a non-linear sorption and porous diffusion model that accounts for migration of polar VOCs such as hexanal, as well as a model that accounts for for hindered diffusion in the nanocomposite barrier layers. If the proposed nanocomposite barrier layers are proven to work in SIPs, they can be applied to reduce emissions from many other consumer products and building materials. The ability to reduce or even eliminate indoor air contaminants at the source will revolutionize the indoor air field allowing fresher, healthier and more productive indoor environments, while at the same time lowering energy consumption by enabling tighter "energy-saving" building envelopes.