Hi Afurber This is a long established question and believe it or not comes up on every single project we do. Steel and concrete are the fundamental materials of the majority of construction projects and on each project we always look at the pros and cons of each. The factors usually considered are: ability to span long distances, weight, stiffness, depth of structure, ability to integrate services, fire protection issues, durability, maintainability, speed of erection, fabrication cost, programme (time) implications, sustainability, embedded energy, acoustic properties, availability in the market, cost (of course) and a few others. These all get assimilated into the overall project ‘equation’ and a decision is reached. In the UK office buildings tend to be most economic (less expensive) in steel and residential/hotel in concrete. How’s that?