# System for Indoor Comfort and Health Monitoring Tested in Office Building Environment
## 4 Results and Discussion
A significant variation in TVOCs was registered from 18 July 2023 to 21 July 2023, when several experiments were carried out in the CATL, leading to temporary values of up to 1000 ppb, which might indicate high chances of experiencing health symptoms. The remaining monitoring period was characterized by values falling in the recommended intervals of approximately 100 ppb (indicated with a blue line in Figure 12). A proper  
Figure 10: Variation in CO\({}_{2}\) over the preliminary testing period in Office 2 measured using Netatmo weather station. Figure 9: Variation in CO\({}_{2}\) over the preliminary testing period in Office 1 measured using the IoT system. ventilation system and better insulation should be installed, especially in the Chemical Analysis and Testing Laboratory, in order to prevent possible pollutants from spreading to other offices. Figure 13 shows the variation in HCHO over the testing period inside Office 1. All of the registered values fell below the permissible exposure limit of 0.75 ppm according to [41], usually 0.02 ppm on average. The spike of 0.07 ppm, which was registered due to the unpacking of new equipment, is lower than the PEL suggested by the California Department of Health and was registered on a different day than the period with high TVOC values. However, this peak exceeds the maximum formaldehyde value of 0.05 ppm, which is currently just a recommendation from the European Union. The monitored values indicate that HCHO is not the main chemical component of the monitored TVOCs. The conditions resulting from the formaldehyde-releasing equipment were temporary since this was moved to another laboratory. Figure 11: Variation in CO\({}_{2}\) over the preliminary testing period in PV-testing laboratory measured using Netatmo weather station. Figure 12: Variation in TVOCs over the preliminary testing period in Office 1 measured using the IoT system. The variation in PM over the testing period inside Office 1 is shown in Figure 14, with a display of PM 1, PM 2.5 and PM 10 values as well. The maximum average values over a year period are 10 \(\mathrm{\SIUnitSymbolMicro g}\)/m\({}^{3}\) for PM 2.5 and 20 \(\mathrm{\SIUnitSymbolMicro g}\)/m\({}^{3}\) for PM 10, while for PM 1, there are no limitations. In the case of Office 1, for the monitoring period, there were maximum average values of 13.88 \(\mathrm{\SIUnitSymbolMicro g}\)/m\({}^{3}\) registered for PM 2.5 and 14.94 \(\mathrm{\SIUnitSymbolMicro g}\)/m\({}^{3}\) for PM 10. The values suggest that, generally, the monitored concentrations do not put any individuals at risk. The peaks registered between 21 July and 24 July 2023 are due to a cumulative effect given by the fact that the office space was cleaned in the respective period only on 19 July 2023 as well as on 25 July 2023. In order to test the validity of the IoT system for monitoring indoor comfort and health, a Netatmo weather station was used simultaneously in the same environment. The comparative variation in values registered by the two systems is presented in Figure 15.  
Figure 6:0 Variation of PM over the preliminary testing period in Office 1 measured using the IoT system. Figure 6:1 Variation in HCHO during the preliminary testing period in Office 1 measured using the IoT system. The comparative variation in CO2 shows very similar registered values, proving the functionality of the newly developed IoT system. Generally, the IoT system shows slightly higher values (6% higher, on average) than the Netatmo weather station. This is due to the higher sampling interval of the sensors included in the IoT system, which measures the envisaged parameters each minute, while the Netatmo weather station registers a value once every 5 min. Being a commercial and widely used weather station, Netatmo has been placed on several office premises in order to determine the comfort of the users and the variation in CO2 depending on the purpose of the monitored office as well as on the occupancy rate in each room.