With complex building designs fire engineering techniques can be used to justify for example, open atria within a building. For simple atrium designs basic zone model calculations can be performed to analysis the time taken for smoke to fill down to head height on the top storey, which can then be assessed against the time taken to evacuate that storey.

For more complex designs, Fusion Fire Engineering can use Computation Fluid Dynamic (CFD) software packages to model the development of fire within a building design and the movement of heat/smoke around that design.

Fusion can also use CFD models to justify deviations from standard natural ventilation systems in residential common corridors, or for smoke clearance systems in basement car parks.