Stack effect is defined as airflow in shafts induced by indoor-to-outdoor temperature differences that lead to density differences and flow. Due to variable pressures and temperatures between floors in a multi-story building, stack effect can be quite troublesome in the event of a fire emergency.
Did you know that asphyxiation due to smoke inhalation is the lead cause of fire-related deaths? This cause exceeds burns by a 3:1 ratio. This harsh reality is what drives certain building codes such as enclosed elevator lobbies in order to protect occupants from both fire and smoke.
Elevator lobbies provide quite the design obstacle when trying to integrate openness and sunlight into a multi-story building. This atrium area provides a critical first impression for the patrons of the building and a traditional elevator lobby does not allow for much flexibility when it comes to aesthetics.