3. Air evolution in a plant

3.1 Winter conditioning

A room requires a minimum supply of fresh air to meet the hygienic needs of its occupants. As this air is cold and dry in winter, it needs to be heated and humidified. To ensure the comfort and preservation of the building, the flow rate of circulated air can be higher than the minimum flow rate. For reasons of economy, part of the return air is sometimes recycled, as it is warmer than new air.

To facilitate humidification of the fresh air, it is preheated in the BPC preheating coil (figure 25 ), usually preceded by a PF prefilter.

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