|
|
 |
|
|
|
|
|
| |
Exhaled carbon dioxide affects the indoor air quality (IAQ)When breathing in, a human absorbs oxygen from the air and releases carbon dioxide, water and volatile organic olfactory substances into the air when exhaling.
The air inhaled contains 21% by volume oxygen and 0.035% by volume carbon dioxide, the air exhaled contains 16% by volume oxygen and 4% by volume carbon dioxide.
Thus, in interior rooms that are not ventilated, the carbon dioxide content rises continuously depending on the number of persons in the room, whereas the oxygen content barely changes.
In a fully occupied and insufficiently ventilated room, the carbon dioxide concentration rises from 0.035 to 0.14% by volume, however, the oxygen concentration drops only from 21.0 to 20.9 % by volume. | |  | | | Carbon dioxide causes tirednessAlthough carbon dioxide is toxic for humans only from a concentration of 2.5% by volume, it does affect a person's well-being and fitness at a much earlier time:
Carbon dioxide causes tiredness starting from a concentration of 800 ppm (0.08% by volume)!
In 1858, Max von Pettenkofer already proposed a maximum value of 1000 ppm carbon dioxide for schools („Pettenkofer maximum value“). In order to ensure the continuous observance of this limit value, which is still effective today, the standard DIN 1946-6 requires an outside air volume flow of 30 m3/h per person. DIN1946-2 defines 1500 ppm carbon dioxide as the hygienic guidance value for interior rooms.
In view of today's building standards and the high impermeability of building walls, this value cannot be reached by occasional airing or tipping of windows, neither in conference rooms nor in low-energy houses.
Constant ventilation by means of open windows increases energy consumption, the ensuing draft results in colds and is considered unpleasant. | | | | | Demand-controlled ventilation is the answerIn order to maintain indoor air quality (IAQ), demand-controlled ventilation (DCV) is needed in such rooms and buildings, and this is possible with the carbon dioxide measuring system offered by J. Dittrich Elektronic:
The infrared carbon dioxide measuring system MF420-IR / -LC determines the concentration of carbon dioxide in the room air and supplies this value - either via an intermediate limit monitor or directly - to a ventilation system, which controls the supply of fresh air as needed.
This saves energy, decreases costs and increases the well-being of all persons present.
Carbon dioxide is considered the leading substance for the pollutants that can lead to „sick building syndrome“. It is assumed that the occurrence of these symptons can be reduced by 70 to 85% through increased air-conditioning controlled on the basis of the carbon dioxide content in the air.
|
|
|
|
|
|
|
|
