Decentralised vs. Central Ventilation...
Decentralised Ventilation is mechanical ventilation for one room only. Central Ventilation is
mechanical ventilation of more rooms by once device.
Central Ventilation is provided by units with bigger dimensions than units for decentral ventilation, since these has to supply higher air volume. Units for central ventilations are usually located in the technical room where they are not annoying the users by high noise level and they are not blocking any space. Central ventilation systems require ducting for supply and extract air, which are often difficult to place in the way to do not disturb. Central ducting systems require cleaning every year, which is complicated. Cost investment of the installation of ducting and theirs covers are usually in the same level as the purchase price of the ventilation unit. Another aspect is regulation and controlling of these systems in order to achieve minimum operation costs and distribution of the air to there where is needed. The advantage is, that suction and exhaust does not have to be located on the outside wall and if so, there are always only two openings.
Decentralised Units are used for ventilation of one room only. Theirs dimensions vary from very small ones located in to the wall, to bigger ones with dimensions similar to smaller radiator. These units ventilate only selected rooms and when needed. Theirs advantage is, that these units can be operated according to sensors of quality of the air (Air Quality sensors -AQS), typically by CO2 sensor or relative humidity sensor. Thanks to the sensors the unit ventilates only when the concentration of pollution in the air is above set level – this means “ON DEMAND”. This ensure, that the energy consumption during ventilation is at minimum level, about 35% lower than ventilation without sensors.
More powerful units can supply in to the room bigger air volume of the air in case of need than central units and thus can ventilate the room faster and better.
It is necessary to consider more suitable solution for each specific project.