IoT Sensors For Indoor Air Quality. Just A Gadget Or A Useful Device?
<p style="text-align: justify;">Today, we see in the market numerous companies offering multi-sensors for indoor air quality with a trendy aesthetic design and connectivity to smart phone, wi-fi etc. </p><p style="text-align: justify;">In their marketing communication, the manufacturers seem to focus, first of all, on a wide range of measured parameters, from conventional up to quite exotic. Such an extensive range of parameters may perhaps impress the “ordinary consumers”, meanwhile it rather causes sceptical smiles among the specialists in the field of ventilation and indoor air quality, especially when it comes to the private residential sector. </p><p style="text-align: justify;">The conventional values such as relative humidity and CO2 concentration can be used for modulating the airflow in a dwelling, a principle known as demand-controlled ventilation, but what to do with the rest of parameters, knowing that there is no unambiguous link between the measured values and the required ventilation control algorithm?</p><p style="text-align: justify;">Therefore, a legitimate question arises: are these devices a useful thing helping to ensure a healthy air in the buildings, or just another trendy gadget? The answer, in my opinion, depends a lot on the targeted user segment. Let’s look at them one by one.</p><p style="text-align: justify;"><strong>Residential buildings</strong></p><p style="text-align: justify;">In the “average” individual house or an apartment the CO2 level is correlated to the relative humidity. In other words, if you control the humidity then you also control CO2. That is why the existing humidity-controlled ventilation systems ensure already quite a good level of indoor air quality using a limited amount of electronics or no electronics at all.</p><p style="text-align: justify;">For other parameters such as fine particles for instance (dust, pollen, organic compounds), it is not obvious how the ventilation system should react when their indoor concentration exceeds an acceptable level. This increase may be just due to a high concentration of these particles outside and the solution to the problem would be to install additional filters rather than modulate the air flow. Except for some specific cases, the homeowners would not install a sophisticated air cleaning system in the garage or attic of their houses and would opt for a simple, affordable solution. And then, if simple, conventional filters are installed, the permanent measurement of the parameters no longer seems necessary.</p><p style="text-align: justify;">As for the connectivity of the sensors, I agree that it allows the inhabitants to see the air quality status on their smart phones. But being realistic, I believe that they would play with this applications couple of times and then pass to more interesting things…</p><p style="text-align: justify;"><strong>Commercial buildings</strong></p><p style="text-align: justify;">In the non-residential sector such as offices, business centres, shopping malls, schools etc., the situation is quite different. The size and the complexity of the ventilation or air handling systems used this sector can justify additional equipment and control algorithms related to improving the indoor air quality, for instance, switching on some specific filters when they are required. In this case, a wider range of the measured air quality indicators could be of use. Moreover, the connectivity of the sensors can also provide a meaningful contribution.</p><p style="text-align: justify;">First, the signals from the sensors can be transmitted via wi-fi or a field bus and used directly as a feedback for the automatic control of the ventilation or air handling units. </p><p style="text-align: justify;">In addition to that, we can go beyond the real time control of the ventilation system. The measured values can be transmitted and stored in the Cloud for monitoring and further analysis. A dedicated software (AI?) could detect correlations between indoor air quality and numerous factors related to the building and then give recommendations to the owner or operator regarding the subjects such as arrangement of workspaces in an office, optimal class scheduling in a school, use of better construction materials for refurbishment in a business center, preventive maintenance etc.</p><p style="text-align: justify;">We can also wonder if the Edge and Cloud technologies will replace the widely used today field buses (Modbus, BACnet, KNX, etc.) and in which perspective. But It is another debate…</p><p style="text-align: justify;"><strong>From quantity to quality</strong></p><p style="text-align: justify;">In conclusion, I would say that in the field of indoor air quality, as in many other areas, the availability of numerous sensors is necessary, but still not sufficient to the success of an IoT application. To make it successful we would need some additional tools (software, algorithms) allowing us to bring the system to a new quality level providing healthier indoor air, better energy efficiency, security, comfort, and other things visible by the customer. And a closer collaboration between multi-sensor manufacturers, IoT specialists and HVAC producers will contribute, in my opinion, to the development of such solutions in the longer run.</p><p style="text-align: justify;">#IoT, #IAQ, #indoorairquality, #buildingautomation</p><p style="text-align: justify;"> </p>