As advertised by the XPS manufacturer, there was a significant reduction in the total GWP due to the removal of HFC–134a. However, the GWP of the new XPS insulation is still two to three times higher than an equivalent GPS insulation. Although improvements have been made to XPS insulations formulation, the environmental attributes still rank it at the top compared to various other insulations (Figure 4). Material selection matters when developing sustainable houses with low embodied carbon and operational carbon. With a low embodied carbon and the preference of utilization by industry stakeholders interested in developing green buildings, GPS insulations are a good option for sustainable insulation and can be selected for a NZER or NZE house.
Over the past decade, there has been an explosion in demand from stakeholders within the construction industry, inquiring about the impacts to the environment from manufactured products. Individuals can view these impacts from an individual product environmental product declaration (EPD) or base it on an industry-wide average EPD. This document is a signal from a manufacturer or association representing various manufacturers and their commitment to measuring, and hopefully reducing, the environmental impacts of a product; it tells the life cycle story from the extraction of raw materials to the end-of-life use. Unfortunately, EPDs are single documents and there is no combined report which allows an individual to quickly compare products.
Builders for Climate Action have developed a tool called Building Emissions Accounting for Materials (BEAM). This tool allows an individual to calculate the approximate carbon emissions of their building, based on materials they typically choose, and see how those emissions can be reduced through a selection of alternative materials. To use the tool, an individual must simply input the dimensions of their building—low-and mid-rise residential buildings only—and a comprehensive list of all available materials will populate for each building assembly. Each material will have a carbon emissions value, which gives an opportunity to quickly compare materials and select a material fit for the scope of the project.2
Conclusion
This article sheds light on the importance of constructing houses with low operational carbon emissions through energy usage, as well as embodied carbon emissions through manufactured materials. As Chris Magwood from Builders for Climate Action notes, the building industry is good at reducing operational carbon emissions, however, the industry needs to stop developing high embodied carbon emission buildings and move toward low (moderate to zero) embodied carbon emission buildings, or store carbon instead over the next decade to limit the advancement of climate change. EPDs and tools such as BEAM help industry stakeholders evaluate and select which low carbon emission materials can be incorporated into sustainable buildings which meet the needs of current and future generations. Selecting foam insulation materials with low embodied carbon provides a platform for the development of an energy-efficient house with low operational carbon, and ensures embodied carbon has been limited as well.
Notes
1 Learn more about the Proposed Rule 23—Protection of Stratospheric Ozone: Listing of Substitutes under the Significant New Alternatives Policy Program (SNAP), www.epa.gov/snap/fact-sheet-proposed-rule-23-protection-stratospheric-ozone-listing-substitutes-under.
2 More information about Building Emissions Accounting for Materials (BEAM) can be found at BEAM Estimator, www.buildersforclimateaction.org/beam-estimator.html.
Author
Tyler Simpson is a certified passive house designer and principal and founder of TWS Building Science. Rooted in and driven by a passion for building science, design solutions, and products represented by the firm allow the occupants to truly experience how a building should feel and perform. TWS Building Science is focused on providing high performance building enclosure solutions to building owners and industry professionals to achieve better built buildings that last for generations.
