People living in developed societies spend a large part of their lives indoors. This makes the quality of indoor environments an important factor for people’s well-being, comfort and health. To determine and evaluate parameters that influence the quality of life inside buildings a holistic concept called indoor environmental quality becomes increasingly important. This work therefore explores reliable technologies that can be deployed at low cost and low overall footprint in order to make the monitoring of indoor environmental quality widely available. Within the scope of this contribution the design and development of a sensor device for a comprehensive assessment of indoor environmental quality including the measurement of the main parameters determining air quality is described. In particular, the work focusses on methods for gauging carbon dioxide concentrations and so-called volatile organic compounds. To achieve this, two technological approaches have been developed, validated, and combined. A photoacoustic-based detection approach was used to develop a miniaturized, selective gas detection module for carbon dioxide. Furthermore, nano-scaled, functional metal oxide particles have been used as central building block of a microsystem to determine VOC levels and composition. With the help of wireless communication technologies, the developed devices have been converted into sensor nodes and the resulting wireless gas sensor network has been deployed at a secondary school for several months. The analysis of the data has demonstrated that maintaining good indoor air quality in densely occupies indoor spaces is difficult, especially when relying on passive ventilation and high building standards.