Are steel-framed buildings more sustainable than concrete-framed buildings -- or vice versa? This is a question many have asked, resulting in in quite a number of comparisons. The debate was reignited following Larry Silverstein's comments regarding the new WTC enhanced safety measures. Silverstein, the Ground Zero Developer, announced that concrete (2-foot-thick) would encase the core of the building as a measure to provide a higher level of protection in the case of a terror attack or fire. The core houses the building's power systems and elevators. So, from a sustainability perspective, which of the two frames (concrete -- frame and steel-frame) scores higher? Sustainability, as an adjective, will in this context be defined as the innate or intrinsic ability to be defended/upheld. It is important to note that although each material has its own unique benefits, there is need to address which of the two frames will better address future construction needs -- especially when it comes to safety, construction scheduling, and cost. The relevance of further exploring this area of research cannot, therefore, be overstated.Hypothesis: From a construction scheduling, cost, and safety perspective, concrete-framed buildings attract a higher sustainability score.

Modern engineering has made it possible for steel and concrete to be widely used in construction. In the earlier days, most construction made use of thatch, adobe, as well as wood. With the building and construction industry in most parts of the world continuing to experience exponential growth, there is need to determine which of the two materials under consideration is best for structural design of multistoried buildings. When it comes to safety, thick cores or columns of concrete seem to be more effective in protecting against such factors as high winds and debris -- and as Silverstein opined, terror attacks and fire. There is consensus that concrete is relatively fire resistant and can evidently withstand significant temperatures. Fireproofing of steel, on the other hand, is easy and in most cases only requires the incorporation...

The ductility of steel could also come in handy in protecting against high wind loads. It is also important to note that from a structural perspective, steel has some redundancy that could prevent collapse as a result of a bomb blast or earthquake event. On that basis, it is therefore clear that there is need to further interrogate the safety factor as introduced herein so as to determine which of the two identified frames has a higher sustainability score.
Cost is another key issue that ought to be explored, particularly given its relevance in structural planning, development, and construction. On this front, it should be noted that although construction materials are now more expensive than they were a decade ago, the ready-mix concrete cost has largely remained stable. A review of available cost data indicates that from the year 2003, mill prices of structural steel have increased by an average of 50%. This is a significant cost increment, notwithstanding the fact that overall project costs have increased over time. There could, however, be higher labor bills associated with reinforced concrete as the construction period is stretched because of the larger crew requirements -- this is despite the fact that initially, it requires less time to start on the jobsite. Recycled steel is also being favored over virgin steel as it is less expensive. There is need to explore whether the reduced labor costs that come about as a consequence of offsite prefabrication of steel can lessen the cost differential.

When it comes to construction schedule, time is truly money, as the old adage goes. In comparison to structural steel, concrete buildings are deemed faster to build. This is more so the case with proper planning on the part of developers, and with the application of whet is referred to as the 2-day cycle -- a well-known construction process - where an upwards of 15,000 square feet floor space can be "poured" every single day. This is, however, a somewhat labor intensive operation. Cities like Los Angeles and New York…