Material Transparency for LEED v4: EPDs and HPDs for Metal Studs
Editor’s note: Guest blogger Anne Hicks Harney, of Long Green Specs, is our partner in providing product vetting services. Harney offers guidance on writing green specs and on finding products for LEED v4, WELL, and beyond. This is the first post in a series focusing on transparency documents for specific product categories.
Material transparency—where manufacturers disclose vital sustainability information about their products—can be a confusing topic. We are looking for environmental impacts and health impacts of material content while also being worried about sourcing concerns and social equity. It can be hard to find a place to begin. And many folks think it isn’t worth starting as there are no ideal products available anyway.
The only solution is to start somewhere, start anywhere. With that frayed strategy in mind, let’s go ahead and choose something—anything—to talk about: let’s start with metal studs.
Metal studs: ahead of the game
We are starting with metal studs because this portion of the marketplace is ahead of the game when it comes to transparency. The Steel Marketing Development Institute got on board with tracking environmental impacts early. They were among the first to develop environmental product declarations, or EPDs, which are documents that disclose the carbon footprint and other environmental impacts of a product.
In 2015, this trade association developed the “North American Product Category Rule (PCR) for Designated Steel Construction Products,” which covers fabricated structural steel, cold‐formed steel sections, and concrete reinforcing steel used or sold in North America. The development of this PCR—which sets the rules for how you must run a life-cycle analysis and develop an EPD—meant that an EPD that applied to all steel construction products made in North America could now be created.
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The Steel Recycling Institute developed an “industry-wide” EPD, which averages the impacts across lots of different manufacturers, in February 2016. (See our FAQs on EPDs to understand all these acronyms a little better.)
Four major manufacturers on board
Then most of the major steel stud manufacturers followed suit. Now you can find “product-specific” EPDs by the following folks:
If you are looking for a disclosure point in LEED v4 under the Building product disclosure and optimization (BPDO) – environmental product declarations credit, limiting your products to these four manufacturers should result in multiple products that meet requirements.
Realize that these EPDs typically cover metal studs and tracks, headers, shaftwall studs and tracks, connectors, clips, channels, and trim accessories. On a typical job, you will manage to get five disclosure documents from each manufacturer, hitting your LEED limit for the manufacturer and getting 20% of the way to the BPDO disclosure option with one product family.
And if you are looking for manufacturers that have a demonstrated commitment to disclosing environmental impacts, you have found them as well.
Steel’s health impacts: who knew?
We can also look in this category for disclosure of health impacts. While they were at it, most metal stud manufacturers developed Health Product Declarations—HPDs, which disclose ingredients and their toxicity—as well. These vary in quality and version, but they provide a good illustration and some valuable lessons.
- Clark Dietrich has self-declared, version 1.0 HPDs disclosed to a level matching material safety data sheets of 1,000 and 10,000 parts per million (ppm). Note that these HPDs are not LEED v4 compliant.
- Cemco has self-published version 2.0 HPDs, disclosed down to 1,000ppm.
- MarinoWARE has a self-published version 2.0 HPD disclosed down to 100 ppm.
- MBA Building Supplies has a self-published version 2.1 HPD disclosed down to 100 ppm.
What we learn from these HPDs is that steel is made mostly of steel (86%–99%) and zinc (0.4%–10%), and then a number of toxic chemicals that are under 1% in total content.
Steel itself is relatively benign, zinc is an aquatic toxicant and endocrine disruptor, and then the balance of these chemicals run the gamut of carcinogens, organ toxicants, reproductive toxicants, and developmental toxicants.
In one of the HPDs, the manufacturer helpfully explains that its stud products are classified as non-hazardous per the Occupational Safety and Health Administration (OSHA) but then further points out that “processes such as cutting, welding, or brazing to modify or install the product can result in hazardous and/or combustible dust or fumes.” Clearly, all stud products will be cut, welded, or modified as a part of the basic installation process, and this is when these chemicals are released onto the project site.
Let’s reward manufacturers for transparency
In LEED v4, there are two ways to get points—through disclosure alone (one point) and through optimization (one additional point). With EPDs, to get the optimization option, you have to show that 50% of products have environmental profiles that are better than average.
From what we have learned from the HPDs, we realize that there is no opportunity to optimize for health impacts, but can we optimize for environmental impacts?
Not really. We can compare our EPDs from these various manufacturers, and we find that three of them are below average for global warming potential, or GWP (i.e., the carbon footprint is higher than that shown in the industry-wide EPD). Only one, on paper, is superior: the winner is MBA Building Supply. It beats the GWP of the industry average by under 10%, though, which means the difference is basically noise. (Learn more about the perils of comparing EPDs here.) It turns out we can’t optimize for environmental impacts either.
To truly attempt to reduce embodied carbon in your building, performing a whole-building life-cycle assessment will likely achieve more real action than simply choosing one stud over another. But we should applaud the metal stud manufacturers for providing the wealth of disclosure documentation that they have, and we should reward them by limiting the metal studs we use on our jobsites to only those that have disclosure documentation available.
Next time, we will cover all of this metal stud with some gypsum board. Stay tuned.
Anne Hicks Harney, FAIA, has more than 30 years of experience, focusing on high-quality design imbued with a solid technical and sustainable foundation. At Long Green Specs, she provides sustainability-focused construction specifications and building material expertise to architectural firms across the country. She was chair of the AIA Materials Knowledge Working Group and is a member of the USGBC Materials & Resources Technical Advisory Group. In 2016, she was awarded FAIA and LEED Fellow.
Published May 22, 2018