They sound like buzzwords, but they’re serious: embodied energy and embodied carbon. It takes energy to produce structural materials, it generally releases carbon as well. So every piece of a building that we build has a physical cost in energy and released carbon as well as an economic cost. A good discussion of embodied carbon as it relates to structure can be found here: “Structural Design and Embodied Carbon.” Since different materials have different amounts of embodied carbon and since different structural frame types require different amounts of different materials, the amount of embodied carbon varies noticeably with the frame type. It also helps when reading this article to keep in mind that steel-frame buildings have a lot of concrete on them (in foundations and floor slabs) and concrete-frame buildings have a lot of steel in them (as reinforcing). The difference between steel and concrete buildings is therefore less stark than you might expect.
Wood is arguable the best material on both counts, as its use removes the carbon in the material from the atmospheric carbon cycle and its production generally requires less energy than other structural materials. Unfortunately, it is not so good when we judge by other criteria, including structural strength, fire-resistance, and life span. These other aspects can be improved by moving away from traditional stick-built wood framing, for example, by using heavy timber construction, but that also increases the cost.
There is no easy answer, but seeing as how the production of cement is a major contributor to the release of greenhouse gases, this topic is not going to go away.
