Embodied carbon comparison of two structural schemes for an office building

Kestrel Place Developments is building a six-storey office of about 7,200 m² gross internal area in Manchester, on a 7.5 x 9.0 m grid with a central concrete core. The developer's parent company in Frankfurt has a company-wide target on upfront embodied carbon for new buildings, and its tenants increasingly ask for the figure in their leasing decisions.

The structural engineer has two candidate schemes: - scheme A, a reinforced concrete flat slab frame on pad foundations; - scheme B, a steel frame with composite metal-deck slabs on the same foundations type.

The developer wants to know which scheme has lower upfront carbon, by how much, and how confident that answer is. A previous consultant gave a single number for each scheme from a quick tool, and the two numbers were 6% apart. The board does not know whether 6% is real or noise.

You will: - set the scope and method in line with EN 15978 life-cycle modules and the IStructE guidance on calculating embodied carbon; - size both schemes to preliminary level; - take off quantities for substructure, frame, floors and core; - calculate modules A1 to A5 for both schemes using a stated database such as ICE and product EPDs where you have them; - run a sensitivity and uncertainty analysis on the choices that matter most; - write a recommendation with benchmarks.

Done means both schemes have quantities you can defend, carbon figures in kgCO2e per m² with the module breakdown, a sensitivity chart that shows whether the difference survives the uncertainty, and a recommendation the board can act on.