This month, I want to focus on some “tips and tricks” when conducting size-up of a building using a thermal imager (TI). Structural size-up in firefighting is a critical, ongoing assessment of the fire scene that begins on arrival and continues until the incident is under control.
It involves gathering and analyzing information about the building, occupancy, fire conditions, and other factors to determine the best course of action and ensure firefighter and civilian safety. A thorough size-up informs the incident commander’s decisions regarding resource allocation, attack strategy (offensive or defensive), and potential hazards.
Here’s a step-by-step guide to help you.
1. Preparation: Ensure all personnel are trained in TI operation. Familiarize yourself with the Tl’s controls and any advanced settings. Establish safety protocols and proper communication procedures.
2. Initial assessment: Start scanning or conducting a 360-degree assessment of the building as soon as possible while maintaining situational awareness. Use the TI to scan the exterior surfaces for any heat signatures. Identify areas with abnormal heat patterns indicating fire or hot spots and extension. Take into consideration the angle and direction of the sun, which is creating heat called solar loading. Scan across the roof level, observing any chimneys and roof vents, looking for thermal clues. Again, watch for any solar loading created by the sun, which will give you false readings on the TI. Be cognizant of the various types of building/roof construction materials you are scanning, as they will display different emissivity values, which will affect your TI readings. Scan all the building sides to locate potential entry and egress points. Doors and windows that are white hot should be considered infeasible for safe entrance. Do not rely on any temperature measurements on your TI, as these can be very inaccurate. Scan down to the crawlspace and basement levels, observing any windows and possible fire conditions below grade. Try to determine if the fire is below or above grade or in the upper level/upstairs/ attic areas.
3. Structural evaluation: Look for signs of structural compromise, such as large or spreading heat zones, at the same time evaluating smoke and fire conditions (color, volume, and behavior). Note any areas where heat is concentrated, which may suggest active fire or structural weakness. Check for the presence of hazardous materials, special conditions, propane, fuel oil tanks, and overhead powerlines.
4. Occupancy considerations: Observe the time of day when assessing the potential for occupants, their location, or any indications of trapped occupants. Vehicles parked in the driveway and children’s toys and bicycles in the yard could give clues as to how many occupants. Never assume the structure is empty until a 100% clear has been given on an allroom search.
1 An observation of a heated attic vent and three darker windows. (Photos courtesy of Bullard.)
2 3 A darker window (top) indicates little heat; the broken window (above) shows two whiter areas, indicating heat.
5. Ongoing monitoring: Continuously monitor hot spots as fire conditions evolve. Adjust firefighting tactics based on TI feedback. Record findings, including hot spots, fire origin, and fire spread. T