Every storey is a slab of building material. Bio-concrete uses microbial
carbonation and captured CO₂ as aggregate; cross-laminated timber (CLT) is
literally biomass — carbon a tree pulled from the air while growing. Both
lock more carbon into the structure than manufacturing them emitted.
Conventional concrete does the opposite: cement clinker production emits
roughly 0.6–0.9 t CO₂ per tonne of cement, so the building is a net source.
net_carbon(t) = embodied_emissions − sequestered(t)
sequestered(t) = storeys · rate_material · min(1, t / t_saturate)
- Storeys built — how tall the tower is; more storeys means more material captured (or emitted).
- Years elapsed — bio-concrete keeps carbonating slowly after construction; timber's carbon was fixed at harvest and stays locked in.
- Material toggle — switches the whole tower's slabs and its carbon balance model.
- CO₂ uptake flow — shows atmospheric CO₂ (grey) drifting down and being absorbed (turning green) into the material; conventional concrete instead emits CO₂ upward.