Tech Talk: Comparing High Performance Building Envelope Assemblies & Systems

Wood and metal stud framing, having mineral fiber or spray foam cavity fill, with additional continuous rigid insulation applied to the exterior face of the wall are used to build insulated envelope walls.  At first glance, this assembly looks to be a reasonably high-performance envelope but they do not fully satisfy the key elements of #’s 1, 2, and 3 as noted above. Field and factory framed assemblies have many components that need expert installation, which is not always achieved and when poorly constructed, energy performance will suffer. The industry is seeing massive price increases for lumber and steel (as well as other components) so these framed assemblies can be expensive.

A second example would be Insulating Concrete Forms (ICFs).  They are extremely strong, durable and provide low maintenance and good insulating qualities, but have high material costs, are more difficult to construct as an infield build and use concrete.  They currently have a limited acceptance in the marketplace. Therefore, ICFs do not score well in meeting the key elements of #’s 1, 2 and 3 as noted above. To explore this further read this article, “Why Building with Concrete is Not Sustainable.”

Metal-faced factory façade panels with various core materials, including EPS, Polyurethane, Polyisocyanurate and Rock Wool have become popular within the commercial building community. These factory produced cladding panels are attractive, have high insulating value and are very constructable.  However, they are mainly limited in their use as wall cladding on buildings, because they do not provide axial load capabilities, e.g., floor on top of a floor and/or roof on top of a wall. Therefore, they must be attached to steel frames that provide the building’s axial load capacities.  They are costly and are used primarily on multi-story buildings located in intense urban settings or on climate controlled industrial buildings.  For the reasons mentioned previously, metal faced cladding panels fall short of being suitable for general building construction, are costly and therefore don’t score well when considering the key elements of #’s 2 and 3 as noted above.

SIPs are very constructible because they are sent to the project site as large wall, roof, or floor sections fully fabricated to length, and width, having window, door, and edge treatments ready for field installation.  SIP HPBEs are highly sustainable because they are made with an Oriented Strand Board (OSB) as their inner and outer structural skins. The strand nature of OSB allows it to be produced from small-diameter trees which are harvested earlier in the growing cycle, allowing for faster cycles of sustainable tree replenishment.  SIPs have a core of Molded Polystyrene (MPS) or Graphite Polystyrene (GPS) insulation manufactured using heated steam and both use a blowing agent with very low global warming potential and no ozone depletion.  Both MPS and GPS are moisture resistant, have stable R-value, are inert —and are both 100% recyclable.