The concentrations of carbon dioxide and humidity in crowded rooms are often too high. The average classroom frequently has more than 20 pupils, and the air in the room often becomes stuffy as a result. Investigations in classrooms have shown that especially in winter months the recommended carbon dioxide (CO2) concentrations are often significantly exceeded. Ninety percent of the way into the teaching time, the carbon dioxide concentration exceeded the reference value of 1,000 ppm. In 25 percent of the classrooms, the average value was as high as 2,000 ppm.
Carbon dioxide is an odourless, tasteless gas which is produced when we exhale. Large amounts of this gas cause people to feel unwell, lose their concentration, and become less productive. Especially in areas where lots of people convene, such as meeting rooms, conference rooms, and classrooms, the carbon dioxide concentration in the air should not exceed 1,000 ppm.
Good indoor air quality can be guaranteed with a ventilation system controlled with the indoor air sensor from ABB. Modern new builds and restored buildings have good thermal insulation thanks to energy-saving legislation. The insulation of windows, roofs, and walls leads to lower air exchange values, with the benefit that thermal energy is not lost, but with the disadvantage of increased carbon dioxide concentrations indoors, alongside increased humidity.
The figures show how important it is to have a good indoor environment: Europeans spend on average 90 percent of their time indoors – at home, at work, or in vehicles (car, bus, train). Depending on their age and activity level, people inhale ten to 20 cubic meters of air per day. This corresponds to a mass of 12 to 24 kilograms of air – significantly more than a person consumes through food and drink. Indoor air plays an even bigger role in our health than outdoor air, which is often cited as a source of problems. For this reason, the air indoors should not be polluted with harmful substances. If humidity levels are too high, hundreds of types of bacteria, fungi, and molds can grow indoors, leading to respiratory diseases, allergies, and asthma and weakening the immune system. That’s why good indoor air quality supports a healthy well-being.
The indoor air sensor measures carbon dioxide concentrations in the air, as well as humidity, air pressure, and temperature. The current status of all four values can be viewed at a glance on the display. Upper limits for carbon dioxide and humidity levels can be set with the keypad. When the thresholds are exceeded, the display turns red, and a relay is also activated. At that point, the windows automatically open or a ventilator switches on in order to return the indoor air to an optimal condition. This can also be set using the keypad. The indoor air sensor continues to monitor the values and switches the relay off again when the levels drop below the set values. The windows close and the ventilator switches off.
In buildings without electrically operated windows or ventilators, a Busch-iceLight or Busch Infolight can be installed. The LED lights are linked to the indoor air sensor and signal when windows should be opened or closed or ventilators switched on or off.