Two hypothetical buildings with different leakage characteristics were used to study the effect of the opening of stairwell doors on a top-injection stairwell pressurisation system. A flow network program called SMOKESIM was used to perform the simulations. It was found that roof leakage plays a role in whether the design number of open inside stairwell doors should be placed at the top or the bottom of the stairshaft for the most critical design. The data obtained also show that a much bigger fan size is needed when the smoke control system is designed with the outside door open than when a number of inside doors are open. The results also help assess the usefulness of published leakage data in the design of top-injection stairwell pressurisation systems.

KEYWORDS: stairwells, doors, performance, pressurised stairs, leaking, properties, computer programs, calculating, roofs, location, fans, sizing, smoke ventilation, pressurisation, designing.