# Ensuring Energy Efficiency of Air Quality Monitoring Systems Based on Internet of Things Technology
## 4 Results  
Comparison of Different Types of Sensors and Their Power Consumption in Air Quality Monitoring Systems  
Choosing the right sensor for an air quality monitoring system is an important factor for determining the accuracy of measurement, battery life, and total cost of a system. The power consumption of sensors is one of the key parameters that must be taken into account when designing such systems, as it affects their autonomy and efficiency (Table 1). Different types of sensors are used to monitor air quality. Dust sensors (PM\({}_{2.5}\) and PM\({}_{10}\)) measure the concentration of fine particles in the air. Among them, optical sensors are highly accurate, due to the use of laser light to count the particles, but they are characterized by relatively high power consumption. Piezoelectric sensors have lower power consumption but provide less accuracy because they measure the changes in the mass of the filter on which the particles settle. Gas sensors are used to determine the concentration of gases such as CO\({}_{2}\), NO\({}_{2}\), and SO\({}_{2}\). Electrochemical sensors exhibit high sensitivity due to chemical reactions, but they can also be sensitive to interference. Semiconductor sensors change their conductivity when exposed to gases, making them an affordable, low-cost option, although their selectivity is lower compared to other types. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sensor Type** & \begin{tabular}{c} **Principle of** \\ **Operation** \\ \end{tabular} & \begin{tabular}{c} **Power** \\ **Consumption** \\ \end{tabular} & **Advantages** & **Disadvantages** \\ \hline Optical Dust Sensor & Laser scattering & High & High accuracy & \begin{tabular}{c} High power \\ consumption \\ \end{tabular} \\ Piezoelectric dust sensor & Changing the filter & Low & Low power & Low accuracy \\ \begin{tabular}{c} Electrochemical Gas \\ Sensor \\ Semiconductor Gas \\ Sensor \\ Temperature and \\ humidity sensor \\ \end{tabular} & Chemical reaction & Average & High sensitivity & \begin{tabular}{c} Sensitivity to \\ interference \\ \end{tabular} \\ \begin{tabular}{c} Semiconductor Gas \\ Sensor \\ Temperature and \\ humidity sensor \\ \end{tabular} & \begin{tabular}{c} Change in \\ conductivity \\ \end{tabular} & Low & Low cost & Low selectivity \\ \begin{tabular}{c} Temperature and \\ humidity sensor \\ \end{tabular} & Resistance change & Very low & \begin{tabular}{c} Low cost, high \\ reliability \\ \end{tabular} \\ \begin{tabular}{c} TSI (Optical Dust, \\ Industrial) \\ \end{tabular} & \begin{tabular}{c} Laser \\ scattering \\ \end{tabular} & High (2–5 W) & High accuracy, industrial & High power consumption, high \\ \begin{tabular}{c} Aeroual \\ (Electrochemical/ \\ Optical) \\ \end{tabular} & \
\begin{tabular}{c} Chemical \\ reaction/laser \\ scattering \\ \end{tabular} & Average (0.5–2 W) &
\begin{tabular}{c} High accuracy, \\ modularity \\ \end{tabular} & High cost, requires calibration \\ \hline \hline \end{tabular}  
* **Note:** Data for TSI and Aeroual are based on the typical specifications of industrial sensors (e.g., the TSI DustTrak for PM\({}_{2.5}\)/PM\({}_{10}\) or Aeroual Series 500 for gases and dust). Power consumption is estimated for those portable models suitable for IoT systems.  
\end{table} 
Table 1: Comparison of the power consumption of different types of sensors. Temperature and humidity sensors also play an important role in air quality monitoring systems. Resistive sensors, which change their resistance depending on temperature or humidity, are an energy-efficient and low-cost option. The power consumption of sensors is influenced by several factors. The principle behind their operation determines their basic level of power consumption: for example, optical sensors require more energy due to their use of laser radiation. The frequency of measurement is also a critical parameter--the more often measurements are taken, the more energy is consumed. The presence of additional functions, such as a backlight or display, increases power consumption.