Carbon impact from insulation is quite low. Foam insulations (specifically SPF) typically have a smaller impact on carbon than mineral fibre due to their manufacturing process—there is no need to dig up raw materials (e.g. rock or sand), transport them hundreds of kilometres, melt them at extremely high temperatures, then transport bulky board stock to its destination. In conjunction with the higher amount of carbon created through manufacturing, board stock also generally needs a control layer behind the insulation, the transportation of which leads to an even higher impact on the carbon footprint of the entire building enclosure. This being said, if the use phase of the building is included, all insulation products save carbon, so the differences between the insulations are negligible.
Transporting SPF is quite efficient, as a set of 0.9-kg (2-lb) closed-cell SPF comprises 10.6 m3 (4500 fb) of insulation, and a set of 0.2-kg (0.5-lb) open-cell SPF comprises 42 m3 (18,000 fb). That being said, the amount of board feet per truckload of SPF can range between 425 m3 (180,000 fb) for 0.9 kg of closed-cell SPF and 1699 m3 (720,000 fb)
for 0.2 kg of open-cell SPF. These amounts are at a minimum 9:1 transportation ratio of board stock insulation to a traditional closed-cell SPF insulation system. Not accounted for in this ratio is the control layer membrane that must be installed in conjunction with the basic board stock insulation product. Transporting SPF results in fewer trucks on the road, which in turn results in lower carbon emissions and reduces the flow of everyday traffic and onsite congestion.
Throughout this author’s 15 years in the construction industry, some architects have been heard to say they will not put “plastic on their walls.” Yes, using SPF means ‘plastic’ is being placed on walls, but it provides a function—namely, water control, vapour control, air control, and thermal control. Board stock—whether foam or mineral fibre—also uses plastic in production, for packaging. Packaging is useful for shipping, but does not have a function afterward, except to keep the product together. In other words, plastic is being used regardless of the insulation type, but with board stock it is diverted to the landfill once the product is installed. A quick calculation estimates there can be more than 650 m2 (7000 sf) of wasted plastic packaging per truckload (based on an R-20 board packaged and shrouded). There is potential for the plastic packaging to be recycled, but the chances of this happening are quite small.
IAQ is always a concern for potential clients determining whether SPF insulation is a viable choice for a project, perhaps because of the ‘astronaut suits’ applicators must wear to install this type of insulation system. However, there is no need to worry—when the SPF system is installed, the occupied space should be vacant and ventilated for 24 hours or another time frame identified by the manufacturer. There are even SPF products available that meet the GreenGuard Gold certification for IAQ. The off-gassing from this type of SPF insulation system is on par with and sometimes even lower than any other type of mineral fibre insulation readily available.
As the famous saying goes, “There is no bad insulation, just bad application.” As a building science practitioner, this author follows that motto, striving to understand the benefits and challenges of all insulation. In a world of self-promotion, it is very important to understand all aspects of a material’s performance and how it interacts with the dynamic environment.
Manufacturing of SPF is very different from mineral wool, as manufacturing of SPF happens onsite by trained professionals, whereas MW is created in a large, static facility. Insulations are not equal, and aspects of performance should be judged based on a system (i.e. building enclosure system) approach. Foam products/systems have the potential to char or burn, but the chances are very low, and following building codes will limit the potential risks. Finally, chemicals have changed over the past few years, and can be environmentally responsible, with a negligible impact on air quality.
At the end of the day, if emotions are involved, it is hard to change the thought process of the designer, but it is in the best interest of the industry to do research and due diligence when specifying construction products and/or building systems.
Rockford Boyer is the technical manager, building enclosure at Elastochem Specialty Chemicals. He has a diploma in civil engineering, a degree in architecture (building science option), and is currently completing the Master of Building Science program at Ryerson University. Boyer has more than 15 years of experience in the enclosure design field, including five years with AMEC, Earth and Environmental and 10 years with Roxul Insulation. He can be reached via e-mail at firstname.lastname@example.org.