# System for Indoor Comfort and Health Monitoring Tested in Office Building Environment
## 3 Methodology of the Proposed IoT System Development
### Solution of the Smart IoT System for Monitoring of Indoor Comfort and Health
Each I2C sensor has a unique address that can use up to 127 devices on the communication bus. \begin{table}
\begin{tabular}{c c c} \hline \hline
**No.** & **Sensor** & **Specifications** \\ \hline \multicolumn{3}{c}{Radon, temperature and humidity sensor} \\ \multicolumn{3}{c}{Manufacturer series: RadonEye Plus2 RD200P2;} \\ \multicolumn{3}{c}{Wide measuring range: 0-9435 Bq/m3 (0.1-255 pC/1);} \\ \multicolumn{3}{c}{Power supply: 12 V DC, 65 mA;} \\ \multicolumn{3}{c}{Sensitivity: 1.35 cpm/100 Bq/m3;} \\ \multicolumn{3}{c}{Precision: \(<\)10\%: 4/370 Bq/m3;} \\ \multicolumn{3}{c}{Accuracy: \(<\)\(\pm\)10\%.} \\ \hline \multicolumn{3}{c}{Netatmo Smart Horne weather station} \\ \multicolumn{3}{c}{Manufacturer: Netatmo;} \\ \multicolumn{3}{c}{Temperature measurement range: 0-50 \({}^{\circ}\)C;} \\ \multicolumn{3}{c}{Accuracy: \(\pm\)0.3 \({}^{\circ}\)C} \\ \multicolumn{3}{c}{Humidity measurement range: 0-100\%;} \\ \multicolumn{3}{c}{Accuracy: \(\pm\)3\%.} \\ \multicolumn{3}{c}{CO2 sensor measurement range: 0-500 ppm;} \\ \multicolumn{3}{c}{Recording frequency: every 5 min.} \\ \hline \multicolumn{3}{c}{Development Board Specifications} \\ \hline \multicolumn{3}{c}{Microcontroller—48 MHz SAMD21 Cortex®M0 + 32 bit low power ARM® MCU;} \\ \multicolumn{3}{c}{ARDUINO MKR WIFI 1010} \\ \multicolumn{3}{c}{Board Power Supply (USB/VIN)–5 V;} \\ \multicolumn{3}{c}{Circuit Operating Voltage-3.3 V;} \\ \multicolumn{3}{c}{Digital 1/O Pms;} \\ \multicolumn{3}{c}{Analog Input Pms—7 (ADC 8/10/12 bit);} \\ \multicolumn{3}{c}{Analog Output Pms—1 (DAC 10 bit);} \\ \multicolumn{3}{c}{Radio module—u-b-box NIMA-N/102;} \\ \multicolumn{3}{c}{Communications—WiFi, Bluetooth®, UART, SPI, I2C;} \\ \multicolumn{3}{c}{Microchip® ECC508 crypto chip;} \\ \multicolumn{3}{c}{Arduino IoT Cloud Compatible.} \\ \hline \hline \end{tabular}
\end{table} 
Table 6: \(Cont.\)PM 1, PM 2.5 and PM 10 are measured using the PMS5003 particle sensor, which uses serial UART communication. This sensor uses laser scattering to radiate particles suspended in the air and then collects scattered light to obtain the curve of scattered light changes with time. The microprocessor calculates the equivalent particle diameter and the number of particles with different diameters per unit volume. RadonEye Plus 2 is a device that measures the indoor radon concentration and is designed to connect to a web database and IoT systems. The device is characterized by a pulsed ion chamber and data communication through Wi-Fi (internet) and Bluetooth LE (Android/iOS). The connection of the Netatmo smart home weather station is achieved between the main indoor module and the internet router through Wi-Fi 802.11 b/g/n (2.4 GHz) or is made wirelessly through long-range radio (868 MHz). The IoT system configuration for indoor comfort and health parameter monitoring is shown in Figure 1, while Figure 2 shows the connection of the sensors to the Arduino development board. The real-time environmental monitoring system (air quality) design is based on Arduino MKR WiFi 1010, as specified in Table 6. It is an IoT system that is connected to the Arduino IoT Cloud. An Application Programming Interface (API) enables the integration of this system with other possible ones, thus making the system modular, custom-made and replicable. A preliminary interface for the user was implemented. Figure 1: Configuration of the IoT system for indoor comfort and health monitoring. Figure 2: Sensors connected to the Arduino development board. The following paragraph details the sensors' specifications and their communication. The Sensirion SCD30 module needs a DC supply voltage in the range of [3.3 V; 5.5 V] and uses a maximum current of 75 mA during measurement. The module has I2C and UART communications and PWM output. The Sensirion SFA30 module requires a DC supply voltage in the range of [3.15 V; 5.5 V] and has a maximum supply current of 5 mA during the measurement. For communication, the module has i2C and UART interfaces.