Indoor air quality is a crucial factor in providing people with a healthy environment that does not impact productivity and well-being. Air quality is determined by air temperature, humidity, and pollution. Air temperature in rooms can be regulated with heating and cooling systems, humidity with humidifiers, and pollution with room ventilation. However, not everything is so simple. These factors are interconnected and dependent on each other, making seemingly simple air quality control a nuanced and subtle regulation system.

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For example, the moisture in the air needs to be evaluated in relative terms, because the saturation of moisture in the air varies depending on the air temperature. For instance, in a closed room, there may be 10 litres of water in the air, which at +20 °C air temperature constitutes 30% relative humidity. Such humidity is healthy for humans and does not harm the eyes, skin, or respiratory system. However, if the room's air temperature is raised to +24 °C, the relative humidity at the same absolute humidity will be only 22%, which significantly dries out the skin, eyes, and airways. Air ventilation is also a significant source of drying during the heating season; for example, the relative humidity of outdoor air at -10 °C is 50%, but when this air is heated to +20 °C, its relative humidity decreases to only 8%. Therefore, when considering air quality, it is essential not only to regulate these indicators with available technical solutions, but also to prevent over-heating, over-cooling, and over-ventilation of buildings.

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