Steel is a metal alloy composed mostly of iron, with up to 2% carbon, as well as some other alloys, depending on the type of steel. It is strong and flexible, allowing for many different applications.
70% of the world’s iron is produced in blast furnaces that are powered by dirty coal.
Iron and steel production accounts for 11% of CO2 emissions worldwide (not including methane emissions). Indeed, for every metric ton of steel produced, 2.33 metric tons of CO2 are produced – and potentially 3.05 metric tons when including methane emissions.
Currently, most steel from demolished buildings is collected and sent to a recycler to melt down and form new steel. While this reduces the amount of raw materials needed to produce new steel, recycling steel is very carbon intensive. Consider the miles that the steel may be transported to a recycler, the energy required to melt the steel down, and then the energy to produce new steel.
Steel reuse, on the other hand, is a game-changer.
Steel reuse entails the removal of structural beams and columns and using them in new projects. Incredibly, up to 97% of the embodied carbon in a reused steel member can be avoided. (Embodied carbon is the amount of carbon emitted in the creation of a construction material.) Reuse is also 10 times less carbon intensive than steel recycling. The 180 Piccadilly Square project (right) in London reused 450 metric tons of structural steel.
…So why isn’t steel reuse as much of a thing?
In the UK, 99 percent of structural steel is recovered, but only 13% is currently reused. One key need is a supply chain of reusable steel members. If demolition (or deconstruction) contractors could capture this steel, this would create an environment conducive to reuse. Moreover, steel is generally bolted together, which makes it inherently demountable. (SCI)
Okay, so steel can be reused. How can we test it to make sure it’s still building-worthy?
Organizations like the UK’s Steel Construction Institute provide guidance on how existing steel members can be tested for strength. …This can also be applied to steel created for a cancelled project. Below is a synopsis of the process:
A building is selected for potential steel reuse, comprised of demountable components of good quality
The firm that will own the material stock (the different steel components) establishes a business case with the demolition (or deconstruction) contractor
This is the amount (and type) of steel likely to be captured from the demolition/deconstruction process.
The firm acquiring the reusable steel documents and arranges the members in preparation of testing.
The tests can include destructive and non-destructive methods, and allows the stock holder to confirm material integrity in preparation for sale
Along with documentation of their characteristics, testing history
Augmentations to the members may be made in accordance with design needs
According to the Steel Construction Institute, “(g)enerally, a structural designer specifies certain material characteristics (which have been assumed in the design process), which are then confirmed as actually
used in the structure by the declaration of properties.
With reclaimed structural steel, the relationship is reversed, so that the design verifications are based on conservative assumptions regarding the material properties, or based on more precise declarations if the material has been tested.”
Steel from other markets (such as international sources) could be reused as well if it meets certain standards.
In Europe, building types are classified in “consequence classes,” which relate to the consequences of structural failure and the associated risk to human life and economic impact. In the steel reuse protocol, SCI states that reclaimed steel can be used for Class 1 (structures with less stringent demand, like agricultural buildings), and Class 2 (applicable to general buildings like residential and commercial structures up to a certain height.) Class 3 buildings are deemed the most high-risk, and therefore should not use reclaimed steel. Moreover, SCI recommends not to use steel in structures exposed to fatigue (like bridges, for example). (Do they hold this value in their updated protocol?)
While “consequence classes” are used in Europe, we use “risk categories” from the International Standards Organization’s Table 1504.5. They are not quite-1-to-1, however, based on European recommendations, reclaimed steel can be used in
—Residential, commercial, and educational buildings up to 15 stories
–Individual floors as large as ~54,000 sq. ft.
–Parking garages as large as 6 stories
Okay, so steel can be reused in a number of building types and sizes. But why would anyone choose old over new in their construction?
Construction costs have continued to increase over the last few years, with the president’s tariff war not helping at all. In the first half of 2025, approximately 16% of contractors had projects cancelled, postponed, or scaled-back due to tariff-related impacts. And beyond spending on public nonresidential properties, construction declined by nearly 4% between July 2024 and July 2025. In fact, construction backlog increased to nearly 9 months in July 2025, according to the organization Associated Builders and Contractors. More than 80% of members received notices from their suppliers that material costs were increasing.
Nearly 25 percent of steel is imported to the US, with the bulk coming from Mexico and Canada. Meanwhile, nearly half of all aluminum is imported, mostly from Canada. This means construction costs with new materials are increasingly volatile. Deconstruction and reuse of steel has the opportunity to shield the industry from this with the localization of sourcing – saving time and money.