ORIGINAL RESEARCH article
Front. Built Environ.
Sec. Indoor Environment
Volume 11 - 2025 | doi: 10.3389/fbuil.2025.1688582
This article is part of the Research TopicOverall Environmental Quality And Energy Performance Of Educational Buildings: Strategies To Improve Efficiency, Comfort, Well-Being, and Liveability Indoor and Outdoor SpacesView all articles
Data-Driven Environments: Evaluating IoT Sensors and KNX Protocol for Monitoring Indoor Conditions in Educational Facilities
Provisionally accepted
- Building Services Engineering Department, Faculty of Building Services Engineering, Technical University of Cluj-Napoca, Cluj-Napoca, Romania, CLUJ-NAPOCA, Romania
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Educational institutions face a growing challenge in creating indoor environments that support both student well-being and operational efficiency. This case study, conducted within two university classrooms at the Technical University of Cluj-Napoca, Romania, assesses the reliability of a smart building system deployed to monitor indoor parameters. The system, which features integrated wall-mounted Internet of Things (IoT) sensors communicating via the KNX protocol, is evaluated by benchmarking its performance to that of a professional monitor instrument (Testo 400). The methodology involved a mixed-methods approach, combining quantitative data from the KNX-based automation network and Testo 400 monitor with qualitative feedback from occupants on thermal comfort, humidity, and indoor air quality. While a systematic offset was observed, with the professional monitor yielding higher readings, the KNX system demonstrated notable consistency. The statistical analysis revealed a strong Pearson's correlation (up to 0.98, p<0.001) for CO2 and relative humidity, followed by temperature (up to 0.97). Despite successful thermal comfort maintenance, indoor air quality emerged as a significant concern due to CO2 levels frequently indicating severe ventilation deficiencies. Comparative analysis showed minimum CO2 concentrations fell into EN 16798-1:2019 Category II/III, while maximum concentrations exceeded both Category IV (Red rating) and the ASHRAE 62.1-2022 threshold. Beyond validating KNX's reliability for indoor environmental quality monitoring in this specific context, this case study highlights the critical need for ventilation system upgrades in higher education to effectively control high CO2 concentrations and foster healthier learning environments.
Keywords: Thermal comfort, Indoor air quality, IoT sensors, KNX protocol, Testo 400, Carbondioxide, Educational facilities, Indoor environmental monitoring
Received: 19 Aug 2025; Accepted: 22 Oct 2025.
Copyright: © 2025 Rus, Moldovan, Mârza, Corsiuc and Iluţiu-Varvara. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Raluca Paula Moldovan, raluca.moldovan@insta.utcluj.ro
Dana Adriana Iluţiu-Varvara, dana.adriana.varvara@insta.utcluj.ro
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