  This article discusses the development of an IoT system for monitoring and
controlling various devices and systems from different vendors. The authors
considered key challenges in IoT projects, such as interoperability and
integration, scalability, and data storage, processing, and visualization,
during the design and deployment phases. In addition to these general
challenges, the authors also delve into the specific integration challenges
they encountered. Various devices and systems were integrated into the system
and five real-world scenarios in a university campus environment are used to
illustrate the challenges encountered. The scenarios involve monitoring various
aspects of a university campus environment, including air quality,
environmental parameters, energy efficiency, solar photovoltaic energy, and
energy consumption. The authors analyzed data and CPU usage to ensure that the
system could handle the large amount of data generated by the devices. The
platform developed uses open source projects such as Home Assistant, InfluxDB,
Grafana, and Node-RED. All developments have been published as open source in
public repositories. In conclusion, this work highlights the potential and
feasibility of IoT systems in various real-world applications, the importance
of considering key challenges in IoT projects during the design and deployment
phases, and the specific integration challenges that may be encountered.
