# Building Fire Evacuation: An IoT-Aided Perspective in the 5G Era
## 4 Preliminary Design of an IoT-Aided Building Fire Evacuation Control System
### Information Sources and Data Transmission
#### 4.2.1 Fire Hazard Monitoring  
To monitor the environmental fire information in a building, various physical sensors are mainly applied. Thermocouples are the most widely used sensor devices to enable the measurement of temperatures in an enclosure space. The range of the measurements varies from 0 to 1700 \({}^{\circ}\)C by type [58]. To measure the indoor carbon monoxide (CO) concentration levels, CO gas detectors can be used [59]. By installing these sensors in spaces and corridors throughout the whole building, identification of the fire origin and its affecting areas can be achieved. In addition, the state of various fire protection systems can be monitored by additional sensor sources. For example, door lock sensors can be installed to monitor fire doors' open or closed status in buildings. The state condition of firewater systems can be monitored by water flow or pressure sensors. Due to the fact that there is a large amount of environmental and equipment state sensor sources and they are installed everywhere inside buildings, flexibility and simplicity of connectivity may be one of the major concerns. Data communication via wireless networks shows its advantages in this aspect. The transmission of these sensor data runs in a small volume of data and has low refresh rate requirements, so narrowband wireless networks for communication, such as ZigBee, NB-IoT, LTE-M, and Lora, can fit their needs. At the same time, the narrowband wireless networks also support communications among massive low throughput IoT devices at a relatively low cost and low device power consumption. However, the prerequisite of using these wireless communication networks for sensor data transmission is that they should be resistant to high temperatures and dense \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Information Needs** & \multicolumn{2}{c}{**Purposes**} \\ \hline Fire hazard & Indoor fire & Temperature (A11) & Measure the hot gas layer (HGL) temperature at corridors to avoid thermal hazards on the evacuation routes. \\ monitoring (A) & environment (A1) & Smoke (A12) & Measure carbon monoxide level at corridors to avoid toxic smoke spreading on the evacuation routes. \\  & Fire protection & Firewater system (A21) & Monitor the state of firewater systems, such as sprinkler systems, indoor fire hydrant and hose reel installation, etc., to avoid malfunction. \\  & system (A2) & Fire doors (A22) & Monitor the state of fire doors to keep the fire compartmentation intact. \\  & Building & Office buildings (B11) & Count the total occupants entering and leaving the building. \\  & entrances (B1) & Residential and commercial buildings (B12) & Count the total number of occupants entering and leaving the building. \\ People & & Elevator lobbies (B21) & Count the inlet and outlet of the occupants on each floor. \\ counting (B) & Building floors (B2) & Staircully exts (B22) & Count the inlet and outlet of the occupants on each floor. \\  & & Corridors and common & Count the inlet and outlet of the occupants on each floor. \\  & Building areas (B3) & areas (B31) & Collect the occupancy information in buildings. \\  & & Rooms and private use & Collect the occupancy information in buildings. \\  & & areas (B32) & Collect the occupancy information in buildings. \\  & Fire emergency & Fire alarm system (C11) & Provide visual alarms and sound alarms to evacuees. \\ Evacuation & system (C1) & Emergency lighting (C12) & Provide light sources to evacuees. \\ guiding (C) & Evacuation & Exit and directional & Inform evacuees of the directions towards the safe evacuation paths. \\  & guidance & sign (C21) & Provide voice-based evacuation guidance to evacuees. \\  & system (C2) & Public address system (C22) & Provide voice-based evacuation guidance to evacuees. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Information needs for building fire evacuation control. smoke in fire environments.