Steel is ubiquitous in commercial buildings, found in everything from rebar in concrete footings to metal roofing. If protected from moisture and corrosion, steel will last 100 years or more, and at the end of its service life, it can be recycled back into structural components with no loss in performance. There are few materials that combine the strength, ductility, durability, and versatility of steel.
This performance comes at a high environmental cost, however. The iron and steel industry is one of the world’s largest industrial energy consumers, and one of the largest emitters of CO2 in the world. Steel production accounts for about 6.6% of the world’s anthropogenic CO2 emissions, according to the World Steel Association. That is more than cement at 5%, which is often demonized for its carbon emissions.
But the U.S. steel industry has been gradually improving its environmental footprint while improving product performance along the way. To better understand these industry changes and limitations, and how architects and engineers can optimize the use of steel to improve its sustainability, one has to know more about how steel is made.