The state of sustainable steel
Steel serves as the backbone for much of today’s built environment, even as competitive materials win increased interest as products of choice when it comes to green building projects.
But for as much as materials such as wood and insulated concrete forms are positively impacting sustainable construction, steel remains a key component to providing strength and longevity to buildings and other structures worldwide.
Production practices and design strategies over the years have greatly changed the ways in which steel-based projects take shape – and made those construction efforts far more efficient.
These days, an old refrigerator made of steel can be refashioned into a steel beam, and a steel beam from a demolished building can see new life as part of a car door.
Mark Thimons serves as vice president of sustainability for the Steel Market Development Institute, and Brandie Sebastian is manager of life cycle assessment with the Steel Recycling Institute. Both the market development and recycling institutes are business units of the American Iron and Steel Institute, which provides marketing and research for the North American steel industry.
Thimons and Sebastian recently spoke with Proud Green Building about the state of sustainability within the steel industry, how environmental product declarations help developers and the future of steel.
PGB: We hear a lot about sustainable materials in the green building industry. Where does today’s steel stand when it comes to sustainability?
Thimons: Steel is interesting. It’s been around a long, long time. The aspect of steel, the recyclability of steel has been around a long time. It’s occasionally overlooked because that aspect is not particularly new, but it’s an important feature of the product that other construction products don’t necessarily share.
You hear a lot about wood nowadays. If you think about what happens to a wood building or a wood product at the end of life, there aren’t a lot of options. About half of it gets land-filled.
From the standpoint of steel production itself, it’s important to note that the amount of energy required to make steel is considerably lower than it was several years ago. We always use 1990 as a baseline and track the energy reduction and energy used to produce a ton of steel and that energy use per ton has reduced by about 31 percent from 1990 to last year, with accompanying reduction in CO2 emissions. In fact, the reduction in CO2 emissions is a little higher, about 36 percent.
Steel is becoming less environmentally impactful to make. At the same time, there are developments in steel grades, primarily started with the auto industry where much higher-strength steels and more formidable-strength steels are being developed. We’re now starting to look at whether those steels can be used in construction.
From a sustainability standpoint, the characteristic of these steels is interesting in that you can use less steel for a given application because it’s stronger and more formidable. Of course, the less you can use of anything, the lower overall environmental impact.
PGB: A large amount of steel used in commercial structures these days is produced from recycled materials. What has this meant for the industry, particularly from environmental and economic standpoints?
Thimons: It’s a benefit. One of the reasons why steel recycling is so prevalent is it makes sense financially, too. That’s not a bad thing; it’s a good thing to recycle steel and metals in general.
With other products, sometimes the only incentive is the sustainability angle, which can lead to lower levels of recycling if that’s the only characteristic that would drive you to recycle a product.
The use of scrap is integral to the steel-making process worldwide, but especially in North America. Sixty-three percent of steel made in North America comes from recycled steel.
Sebastian: It’s worth noting that all steel produced today has recycled content. Steel scrap is used as an input, a resource in all steel production.
Thimons: Recycled steel is an essential input to the steel-making process. The financial impact comes from whether that resource is less expensive to process and use in the making of new steel versus using natural resources from the ground. In the absence of available steel scrap, there would be an increase in the use of natural drawn-from-the-earth resources. It’s better from a sustainability standpoint, but more efficient financially to use steel scrap than to use additional natural resources.
It’s beneficial for construction companies to harvest steel from buildings to recycle because they can sell it for re-use.
A lot of this is dependent on the price of scrap, which fluctuates over time for various reasons. When scrap is at a particularly high price level, it’s not unusual for demolition contractors to search out buildings that are prime for deconstruction to harvest steel from. Certainly any building that is torn down at the end of its life, the steel is just routinely recycled. I usually say that any steel that ends up in a landfill is by accident because there is no incentive to discard it in a landfill. That’s why the recycling rate of things like heavy structural steel is incredibly high – in the 98 percent range – and for steel products overall at 85 or 86 percent.
Sebastian: Another reason steel is recycled at such high rates is because it’s very easy to separate from other materials. It’s inherently magnetic, so the separation process is easier. When folks are taking down buildings, they set aside steel to be recycled because they can get some money for it as opposed to paying tipping fees and doing things to dispose of it.
PGB: The industry recently has developed a host of industry-wide environmental product declarations (EPDs) for most North American steel construction products. What is driving the development of those EPDs and what does it mean for builders and developers weighing the type of material with which to construct a building?
Thimons: There are a couple of things that drive the development of EPDs. One is a general interest in more transparent information coming from the manufacturing of building products. In reality, one of the strong drivers is LEED. The newer version of LEED – LEED version 4 – allows for credits for LEED certification for various aspects of industrywide or industry average EPDs or product-specific EPDs from a product manufacturer. No question that LEED plays a big part in what we have seen as a proliferation of EPDs from all kinds of products.
Sebastian:LEED is probably the strongest driver, but we’re starting to see EPD aspects being incorporated into other green rating programs, like GreenGlobe, as well as code-specific to the Green Construction Code and ASHRAE. They’re starting to incorporate environment product declaration avenues in those types of documents. They’ve already had whole-building life cycle assessment aspects, but we’re now seeing the EPDs there as well.
PGB: With so many different EPDs out there, is there a difference in steel EPDs and others?
Thimons: One of the controversial aspects of life cycle assessment and EPDs is they have been over the years focused on sort of a fixed list of environmental impacts that experts know how to calculate and measure. One of the contingents we make, and it’s not just us, is that some other products – specifically wood products – don’t fall neatly into the impact categories that are typically measured. There are impacts from the use of wood products – things like land use, biodiversity, end-of-life disposition that aren’t typically included in wood product EPDs. The Sierra Club, of all people, has actually weighed in on this and essentially made those same comments that there are a lot of impacts that aren’t measured or reported for wood products.
For steel we’re not aware of any impact of steel making that we don’t report on. We have a very comprehensive list of impacts, including some that are not typically reported on or required to be reported on.
PGB: Steel was in the spotlight at Greenbuild 2016, the world’s largest showcase of sustainability. What was the message conveyed about steel and its significance to the green building industry?
Thimons: It always starts with recycling and recyclability. In more recent years, our emphasis is on providing wholly transparent information about the environmental impact of using steel in construction. We get a lot of input from architects and designers. Of course, architects are one of the large contingents at Greenbuild, and we get a lot of input that that’s what they’re interested in.
When they’re designing buildings, they want to know what is in the product, they want to know the potential environmental impact for the product and they want to know that for all the products they’re going to use or potentially use.
Much of our effort over the last year or two has been geared toward answering that concern or request, providing as much transparent information as we can on the environmental impacts of steel.
PGB: What is the future of sustainable steel?
Thimons: There are a lot of things going on in the development of new steels, primarily now in automotive, to develop new grades of steel to allow for the more efficient design of buildings. By efficient, I mean using less material to get the same end results. That’s clearly going to be more of a focus in the next five to 10 years. There is a continual focus on reducing the amount of energy to produce steel.
The recycling aspect is obviously going to continue. If anything, the nature of the production process in North America is such that the consumption of scrap on a percentage basis is likely to increase. We think the strengths of steel now in the area of sustainability are going to continue and be further refined. Steel has been around for more than 100 years and in some ways reached maturity in its use, but we’re finding some increasing and exciting aspects of steel driven by sustainability issues.
The potential use of automotive steel in construction wouldn’t have happened if not for some of the drivers in sustainability.
We also have some interesting and long-term research ongoing. Some of it is in conjunction with government agencies, looking at the very nature of steel-making and at radical ways to make steel in the future that would require significantly lower energy inputs and lower C02 emissions.
Those aren’t short-term projects, but they are important projects.
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