Computational Engineering / module 20
Computation for low-carbon structural design
Where the carbon actually is, why the grid moves it more than the material does, and whether a ranking survives the uncertainty in its own factors.
What you will understand
- Say where embodied carbon sits in a structure and when it is decided
- Compare scheme options on a rate basis at concept stage
- Show that span moves carbon more than scheme choice does
- Explain why mass alone does not determine environmental performance
- Test whether a ranking survives the uncertainty in the carbon factors
- Quote a carbon figure with the provenance it requires
Lessons
Where the carbon is, and when it is decided
The awkward shape of the problem: the biggest lever is pulled at the stage with the least information.
What actually moves the number
Four schemes, five spans, and the comparison that shows which decision matters more.
Does the ranking survive?
The factors are uncertain. Test whether the conclusion depends on them — because that is the only result worth acting on.
Module summary
- The largest reductions are available at concept stage, on the least information
- Every scheme's carbon rises faster than linearly with span
- Across ordinary office grids, span moves carbon more than scheme choice does
- Mass and carbon rank schemes differently — the lightest is not always the lowest-carbon
- A ranking is worth acting on if it survives the uncertainty in the factors; test that
- Structural depth is a carbon quantity too, through building height and cladding
- Every factor quoted needs a source and a date, or it should not be quoted
Teaching basis and review status
These are educational models and exercises. Check their assumptions before using the results. The full technical content and every diagram have not yet been independently verified.
Concrete and steel calculations retain their stated first-generation Eurocode teaching basis. Use the standards and amendments specified for your project; do not mix generations without an appropriate design basis.
Read the lesson register and outstanding review notesCheck your understanding
Check yourself
Why can a lighter structural scheme have higher embodied carbon than a heavier one?
Practice
A composite steel frame produces 562 tCO₂e at a 6 m grid and 1 028 tCO₂e at a 12 m grid. By what factor does doubling the span increase the carbon? Give the factor to two decimal places.
Practice
A scheme uses 1 754 t of material and produces 447 tCO₂e. What is its carbon per tonne of material, in kg CO₂e per tonne, to the nearest whole number?