Which observation is a typical sign that a fire is ventilation-limited?

• A. You can't see through windows and interior surfaces are heat damaged
• B. Windows are wide open and the room is cold
• C. TIC shows no heat
• D. There is no smoke

Answer: (A)

Ventilation-limited fires burn in a space where available oxygen is too low for the heat in the room to be sustained at high levels. The heat and smoke build up because combustion is starved of air, so you see dense, obscuring smoke and intense radiant heat that damages interior surfaces. When smoke is so thick that you can’t see through the windows and the interior surfaces are heat-damaged, that combination is a classic sign of a ventilation-limited condition—the space is holding hot, smoky air due to restricted ventilation.

If windows were wide open and the room felt cold, that would indicate better ventilation and less likelihood of a ventilation-limited scenario. A TIC showing no heat or there being no smoke would imply little or no active fire, not a ventilation-limited one.