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Introduction»Articles»4 examples of how to choose the right type of sensor for each room
4 examples of how to choose the right type of sensor for every room
For an immediate assessment of indoor air quality in terms of how stale it is, the first and correct choice is monitoring the concentration of carbon dioxide (CO2).
The term CO2 is well known not only among experts in the field of air conditioning and ventilation in general but also among end customers. The concentration of carbon dioxide is indeed a very good indicator of stale air.
WARNING, however, its measurement is not suitable everywhere. What sensor to choose in specific spaces? Below are the four most common cases.
1. So-called stale air
These are spaces where people frequently move/stay. Examples of such spaces can include:
bedrooms, children’s rooms
living rooms
offices
meeting rooms
classrooms
shopping centers
cinemas, theaters, …
In all of the above-mentioned spaces, the concentration of carbon dioxide gradually rises (among other substances) due to the breathing process of the people present. In such spaces, the best choice is a sensor monitoring the concentration of CO2. It is sufficiently accurate and stable over the long term thanks to the optical sensor.
Principally, a person exhales not only CO2 but also so-called VOCs – Volatile Organic Compounds. These are various chemical substances of organic origin in a gaseous state at normal room temperature, which are primarily the main cause of unpleasant feelings associated with stale air – reduced concentration ability, drowsiness, fatigue, headaches, dizziness, or even nausea. Wherever the predominant source of pollution is people present, CO2 is an excellent indicator of stale air.
The situation there could then look roughly as depicted in the graph on the right.
2. Spaces where CO2 is not the main pollutant
For the choice of monitored variable for effectively controlled ventilation of a given space, we can use a simple rule: first, we need to determine the predominant source of air pollution and then choose the appropriate type of sensor accordingly.
Examples of such spaces can include:
gyms
fitness centers
dressing rooms
toilets
Often, it is quite a large space for people to “stale” it, or they stay there for a relatively short time. Nevertheless, this space can become polluted during their stay, perhaps due to specific activities (odors, sweat, deodorants, cleaning agents, etc.). In such a space, the concentration of CO2 may be at a relatively good level, but the air has an odor or smell, and therefore ventilation is necessary.
In other words, in the above-mentioned spaces, another source of pollution may prevail over the standard breathing process. If we placed a CO2 sensor here, it might not show significantly high concentration values.
The predominant, more indicative indicator of air pollution is indeed the concentration of VOCs. The situation in such a space could then look roughly as depicted in the graph on the right.
A suitably placed VOC sensor will solve the problem excellently.
3. Other sources of odors and smells
The third type of space where air quality needs to be monitored is the indoor environment where there is a significant source of pollution that is not caused by people themselves – the source of pollution is not breathing, metabolic processes, sweating, etc.
This source of pollution can be some materials, chemicals, or technological processes such as:
cooking and frying
various technological processes
fumes from cleaning or disinfecting agents
fumes from perfumes, scented candles, etc.
fumes from furniture, floor coverings, etc.
fumes from paints, ceilings, etc.
Examples of spaces can include:
professional kitchens, restaurants
canteens
newly built/renovated houses and buildings
principally spaces where chemicals are handled, etc.
Here we could mention the same graph as in point 2, so the VOC sensor is the best fit here.
In spaces where multiple sources of pollution mix (e.g., a combined living room with a dining room and kitchen), the best choice is a combined CO2 + VOC sensor.
4. High humidity
Among other important indicators of indoor air quality, of course, is the relative humidity of the air – RH.
This mainly concerns:
bathrooms
laundries
and, for example, kitchens
In such spaces, without proper ventilation, mold can begin to form relatively quickly, especially in the winter months, in corners, in window joints, and so on. Rust can appear on metal objects.
Effectively controlled ventilation with a suitably placed humidity sensor usually satisfactorily resolves this issue.
A suitably chosen sensor can not only solve the quality of the indoor environment in the monitored spaces, but it also allows for effective management of the ventilation system and thus potential energy savings.
