Technical terms

Absolute air humidity

Absolute air humidity is defined as a weight of water vapour in unit of air volume. The unit of absolute air humidity is kg/m3.

CFM - Cubic Feet per Minute - flow rate unite

Cubic Feet per Minute. Unit of measurement of the flow of a gas or liquid that indicates how much volume in cubic feet pass by a stationary point in one minute. 1 cubic foot = 28.3 litres.

CO - carbon monoxide

Colourless, odourless toxic gas, produced mainly during imperfect combustion. Exposure to high concentrations can be very dangerous. Sources of carbon monoxide are mostly: imperfect combustion, smoking and automobiles.

CO2 - carbon dioxide

Colourless, odourless gas. It is produced during metabolic activity of living organisms and during combustion process. During respiration process, aspirated oxygen changes to carbon dioxide, air expired by an adult contains about 35 000 to 50 000 ppm CO2 on average. Concentration in an open air in environment is ca 350-400ppm.

DCV - Demand Control Ventilation

Demand Control Ventilation. It is a name for ventilation systems with instantaneous power depending on current quality of indoor air. That leads to significant savings of energy and costs of building operation.

HVAC - Heating, Ventilating, and Air Conditioning

Heating, Ventilating, and Air Conditioning. This is a name for ventilation systems and equipment that shall positively influence quality of indoor air in a certain way.

H2CO- Formaldehyd

Colourless gas with penetrating odour. It is produced during imperfect combustion of materials containing carbon. It is contained in motor vehicle exhaust gases, tobacco smoke. It exists also in atmosphere, where it is produced by effect of sunlight and oxygen on hydrocarbons contained in atmosphere. It often liberates from materials used in houses and flats, such as wood, splinter boards, furniture, carpets, facing materials etc.

IAQ – Indoor Air Quality

Indoor Air Quality relates to quality of indoor air inside buildings, which can be polluted and can negatively influence health and comfort of occupants. IAQ involves wide range of possible types of air pollution, from microbiological contamination, various allergens to chemical contamination (CO, CO2, VOC, Radon). According to the latest studies, quality of indoor air represents higher risk for health than quality of outdoor air.


A nondispersive infrared sensor (or NDIR) sensor is a simple spectroscopic device often used as gas detector.


Parts per million – unit that means one part of the given substance for 999 999 parts of another, i.e. one part in million.


Radon is a colourless radioactive gas, produced during decomposition of radium, which can be located in base of buildings, eventually in some building materials. It is very heavy gas and so it tends to accumulate at ground level. Radon represents very risk factor for human health..

Relativní vlhkost

Relative humidity of air is a ratio between amount of water vapours contained in air and the highest possible amount of vapours at the given temperature. It is defined in percents. Relative humidity can be calculated as a ratio of absolute humidity of air to the highest absolute humidity of air at the given temperature.

Dew point

Usually, the dew point temperature is stated. It is a temperature, to which it would be necessary to cool air down (at constant pressure), in order to water vapour contained in air becomes saturated water vapour. Saturated water vapour condenses during further cooling and becomes dew.

VOC - Volatile Organic Compounds

Volatile Organic Compounds. There are many synthetic and natural chemical compounds called Volatile Organic Compounds (abbreviation VOC).