This study has been developed to help structural engineers in our practice understand the impact of their design decisions on the embodied carbon of the resulting building. This piece of work is shared in the hope that it will provoke discussion and is not intended to provide design solutions!
It is more interested in sensitivity to design decisions (materials, grids etc) than absolute accuracy in the final figures.
As a baseline scheme we took a generic 8000m2
six storey building with a 9m x 9m column grid designed for an imposed load of 4+1kN/m2
and developed concrete, steel and timber solutions using the most conventional approach for each of these materials (concrete flat slab, composite steel beams with metal deck slabs and glulam beams with cross laminated timber slabs).
With these three baseline schemes we then studied the impact of changing each of the different design parameters in turn on the total embodied carbon.
These parameters included structural arrangement, loading, column grid, material specification, foundation type, structural system etc.
Finally, for each baseline scheme a series of parameters were changed together in steps to look at the potential total variation in embodied carbon that could be achieved within each system.
These included some option to get to very low embodied carbon values but these start to require compromises in structural depth, construction programme, column spacing and loading.
The overarching conclusion would appear to be that material choice has rather less impact on embodied carbon than concrete specification, grid choice and loadings.
This encourages us to focus harder on ensuring lean design and sensible grids whatever the material used.