Nearly 200 members of the United Nations Framework Convention on Climate Change (UNFCC) are parties to the Paris Agreements, an international treaty adopted in 2015 with the long-term goal of mitigating global temperature rises through substantial reductions in emissions. Canada signed the treaty in its first year and passed the Canadian Net-Zero Emissions Accountability Act into law in 2021, committing to a 40% to 45% reduction in greenhouse gas (GHG) emissions by 2030 and net-zero GHG emissions by 2050.
These bold commitments will have significant ramifications for the building industry, which currently accounts for nearly 40% of global annual GHG emissions. The time for environmentally friendlier building materials and decisions is now.
Indeed, environmental factors are now a dominating factor in the decision-making process. The easiest way for an engineer to determine the environmental impact of a building material is through its Environmental Product Declaration (EPD).
International Organization for Standardization (ISO) 14025:2006, Environmental labels and declarations, defines an EPD as a Type III declaration that “quantifies environmental information on the life cycle of a product,” from raw material extraction and manufacturing through installation, use and maintenance to disposal; while ISO 14040:2006, Environmental management – Life cycle assessment – Principles and framework, details the independently verified life cycle assessment (LCA) data upon which Type III declarations must be based, with strict standards for conducting an LCA.
EPDs are completed by third-party sustainability consultants and verified by third-party certification organizations. In recent years, they have been increasingly requested by builders, architects, engineers and contractors, to help reduce their projects’ carbon emissions.
Product-specific vs. industry-wide
There are different types of EPDs to designate groupings of products.
Sector or Industry-average EPDs are developed by industry associations to represent products from multiple vendors within the same sector (e.g. glass-mat gypsum boards, with data averaged from 51 facilities across Canada).
In recent years, EPDs have been increasingly requested to help reduce projects’ carbon emissions.
Single-company, product-specific EPDs are more common. Their LCA may take a cradle-to-grave or cradle-to-gate approach; the former, which accounts for emissions caused by the product’s continued use and eventual disposal, provides a more complete view.
The ability to pinpoint areas for improvement only comes about through product-specific EPDs. A sector EPD, for example, could help an engineer choose spray foam insulation over hydrofluoroolefin (HFO) extruded polystyrene (XPS) in their specifications, but it wouldn’t help them or the contractor source the best closed-cell spray foam insulation.
Defining environmental impact
EPDs detail the impact of a product in six different categories:
1. Global warming potential (GWP)
GWP measures greenhouse gases’ (GHGs’) ability to trap heat in the atmosphere, in comparison to carbon dioxide (CO2). Methane, for example, has a GWP of 25, as its impact is 25 times greater than that of CO2. EPDs report the GWP of a product as the culmination of all CO2 and GHG emissions from its production and use. Closed-cell spray foam, for example, offers a significant reduction in GWP compared to other insulation products.
2. Ozone depleting potential (ODP)
ODP measures a product’s ability to destroy the ozone layer—which protects living things from the sun’s ultraviolet (UV) rays—in comparison to chlorofluorocarbons (CFCs).
3. Acidification potential
Regarding the combustion of fossil fuels, this is the potential for the release of sulphur dioxide (SO2) and nitrogen dioxide (NO2) to increase the concentration of hydrogen ions in soil (which can reduce nutrients) or water in the atmosphere (which can cause acid rain).
4. Eutrophication potential
This on the other hand is the potential for a product’s nitrogen and phosphorus emissions to enrich nutrients in soil or water, which can cause excessive propagation of algae and reduce oxygenation levels, which can negatively affect plant life and groundwater through contamination.
5. Smog formation potential
This is the potential for the product’s emissions to be trapped at ground level and exposed to certain climatic conditions and sunlight. This chemical process can form ground-level ozone, a pollutant that affects respiratory systems.
6. Resource depletion
This is a measure of the depletion of abiotic resources in the Earth’s crust, along with the energy required to transport and process these resources during the product’s life cycle.
Assembly comparisons should include other materials required for the building envelope.
The larger context
Beyond such technical details, the larger context is also important. Assembly comparisons should include other materials required for the building envelope.
Closed-cell spray foam insulation, for example, provides the assembly’s thermal insulation, air barrier and vapour barrier. It significantly reduces the embodied carbon of a building envelope by replacing three products, where more traditional assemblies use mineral wool, fibreglass and full-surface membranes.
There is certainly more to environmentally conscious building design than reducing GWP. Products that help a building save energy result in lower operating carbon emissions over that building’s lifetime. A tighter building envelope benefits everyone.
Embodied carbon in building materials is responsible for 10% of total annual GHG emissions worldwide. As environmental policies and laws change to reflect emission-reduction mandates and society moves towards more sustainable materials, EPDs will become increasingly relevant and promote further use of LCAs and energy modelling.
To reduce the environmental impact of entire construction projects, a centralized database of product-specific EPDs would be of great benefit, helping engineers and architects make better-informed and sustainable decisions.
Mickel Maalouf is a LEED Green Associate and senior representative for sustainable building science with Huntsman Building Solutions.
(This article originally appeared in the January/February 2023 issue of Canadian Consulting Engineer.)
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