MOS VOC “air quality” sensors – long-term stability and use for residential ventilation control

At DTU BYG, the research related to Metal Oxide Semiconductor (MOS) sensors for measuring Volatile Organic Compounds (VOC) dates back to 2014. Our research, as well as other studies published in the literature has shown that MOS VOC sensors are useful to detect high pollution events such as cleaning, painting or high occupation density. These abilities seem to make MOS VOC sensors suitable to complement ventilation control systems, especially with respect to residential ventilation. Demand controlled residential ventilation systems in Denmark are often humidity controlled. This type of control could be complemented by MOS VOC sensor to detect pollution events not related to humidity increase. In addition, the cross sensitivity of MOS VOC sensors to relative humidity could be utilized to potentially replace traditional humidity sensors and save some costs. However, the questions that obviously come from the practice: “Are the MOS VOC sensors reliable and stable enough to be applied in practice?” “Are there any benefits with respect to energy efficiency and indoor environmental quality?” still remain unanswered. Studies on long-term performance of MOS VOC sensors exposed to real life environments are lacking. Some producers test their sensors in laboratory environment, but such data are not publicly available. Data about the influence of ventilation control based on MOS VOC sensors on energy efficiency in Danish context are also missing.
The present project aims to give answers to above mentioned questions by defining following objectives:
1) Investigate long-term stability of Metal Oxide Semiconductor sensors exposed to typical residential environment.
2) Determine sensor properties – sensitivity, linearity, hysteresis by comparing their signal with a reference measurement.
3) Implement at least two tested sensors in a prototype of a ventilation control and demonstrate its functionality.
4) Evaluate developed MOS VOC based control with respect to indoor environmental quality and energy use.