# Ensuring Energy Efficiency of Air Quality Monitoring Systems Based on Internet of Things Technology
## 5 Discussion
### Energy Efficiency Estimation of the Proposed IoT Air Quality Monitoring System  
To assess the energy performance of the proposed air quality monitoring system, a configuration based on the Smart Air sensor, a Zigbee gateway, and a Mini UPS was analyzed. The estimation focused on daily energy consumption, uninterruptible power supply (UPS) efficiency, and projected annual energy use under continuous operation. The assumed parameters for the components were as follows:  
* Smart Air sensor: 0.5 W average power consumption;
* Zigbee gateway: 1.5 W;
* Mini UPS (accounting for charging losses and standby operation): 1.0 W;
* Operational time: 24 h/day; and
* Battery capacity of Mini UPS: 20 W-h.
* Daily Energy Consumption The total daily energy consumption of the system was calculated as follows:
* Smart Air: 0.5 W \(\times\) 24 h = 12 W-h
* Gateway: 1.5 W \(\times\) 24 h = 36 W-h
* Mini UPS: 1.0 W \(\times\) 24 h = 24 W-h  
Total daily energy consumption: 72 W-hBackup Operation Time  
In the event of a power outage, the Mini UPS is responsible for maintaining the operation of critical components. The combined consumption of the Smart Air sensor and the Zigbee gateway is 2 W. With a battery capacity of 20 W\(\cdot\)h, the autonomous operation time provided by the UPS is:  
\[\frac{20\text{ W}\cdot\text{h}}{2\text{ W}}=10\text{ hours}.\]  
This level of autonomy is sufficient for most typical short-term outages in urban environments. The energy efficiency of the Mini UPS can be expressed as the ratio of useful output energy to the total energy consumed for charging and operation:  
\[\text{Efficiency}=\left(\frac{20\text{ W}\cdot\text{h}}{24\text{ W}\cdot\text{h}} \right)\times 100\%=83.3\%.\]  
Annual Energy Consumption  
Assuming continuous operation throughout the year, the projected annual consumption of the system is:  
\[72\text{ W}\cdot\text{h}/\text{day}\times 365\text{ days}=26.28\text{ kW}\cdot\text{h}/\text{year}.\]  
This level of consumption is considered low for IoT-based environmental monitoring systems, especially those capable of real-time multi-parameter measurements. To contextualize the proposed system's energy efficiency, we compared its performance with existing IoT-based air quality monitoring systems. For instance, Ref. [4] reported a daily energy consumption of 100-150 W\(\cdot\)h for a LoRaWAN-based system, while the authors of [21] achieved approximately 90 W\(\cdot\)h/day with optimized data transmission protocols. Our system, consuming 72 W\(\cdot\)h/day (26.28 kW\(\cdot\)h/year), demonstrates improved energy efficiency, which is particularly suitable for battery-powered or resource-constrained deployment. This comparison highlights the proposed architecture's potential for sustainable, scalable air quality monitoring in smart city applications. The evaluation confirms that the proposed system architecture ensures both energy efficiency and operational reliability. With a low daily energy demand, extended backup duration, and UPS efficiency above 80%, this configuration is suitable for long-term deployment in residential, institutional, or smart city environments with limited access to a continuous power supply. Comparative Assessment of Sensor Energy Efficiency and Cost-Effectiveness Using the Integrated Efficiency Index (IEI)  
A Smart Air sensor is a device for monitoring indoor air quality that measures the main parameters of the atmosphere and transmits them to a smart home system or mobile application. LifeQuality sensors are equipped with sensors offering medical measurement accuracy. Non-dispersive infrared sensors provide accurate CO\({}_{2}\) information that is not affected by air pollutants such as aerosols and steam. Industrial-grade digital sensors measure the relative humidity and temperature. Ajax automation devices and scenarios support all these indicators within a given range (Table 6).