When the design of the replacement air supply mode is adopted, the following provisions shall be complied with:
1. The net height of the room should be greater than 27m；
2. The heat source is mainly personnel, equipment (computers, photocopiers, etc.), lights, and the density of personnel does not change much, the amount of personnel activity is light, and the cooling load per unit area of the air-conditioning area should be less than or equal to 120W.
3. The location of the pollution source and the heat source is similar, and the concentration is not large and stable
4. The wind speed at the human ankle should not exceed 02m/s；
5. There should be no other airflow organization in the air-conditioned area.
Displacement ventilation is a special case of lower air supply, the principle is that the cold air layer is sent into the heat and humidity load and pollutants by the action of heat buoyancy lift, the dominant airflow of displacement ventilation is mainly controlled by the indoor heat source, and the upper indoor area can form a vertical temperature gradient and concentration gradient, rather than relying on the wind speed to produce the air supply range, so it is suitable for the area with heat source or heat source and pollution source association, year-round cooling area. When hot air is fed in or the air supply speed is large, it no longer belongs to the category of displacement ventilation, and is a general downward air supply method. In the outer area of the building where there is a large demand for heat load in winter, it is not suitable to use a replacement ventilation system. Comfort air conditioning systems that require strict dust content in indoor air are also not suitable for use.
In areas where displacement ventilation is adopted, if there are other airflow organizations, the effect of displacement ventilation will be greatly affected.