Phased Evacuation: The fire floor, the floor above, and the floor below evacuate first. Other floors receive an "alert" tone and evacuate later if the threat spreads (standard for skyscrapers). Step 4: Draft the Grid and Populate the Intersections

To visualize how this works in practice, consider this simplified excerpt of a matrix for a commercial building: Input / Cause Visual/Audible Alarm (Local Zone) Visual/Audible Alarm (Adjacent Zones) HVAC Fan Shutdown Elevator Recall Fire Door Release Central Station Notification X X X X X X Smoke Detector (Floor 2) X Alert Tone X X X Duct Smoke Detector (AHU-1) X X Waterflow Switch (Zone 1) X X X X X X Testing, Commissioning, and Maintenance

A fire alarm cause and effect matrix is essential for several reasons: