Natural ventilation can be controlled. With certain heat gains emitted from the process to the interior of the building and the outside temperature varying throughout the year and throughout the day, a different airflow is needed to ventilate the building. Depending on the geographic location of the plant, temperature differences over the year can reach as much as 60°C, and daily differences of 20°C. Particularly due to diurnal temperature differences, it is difficult to rely on manual control here.
The main task of the control is to open enough supply and exhaust vents, that is, to produce such a ventilation flow to ensure the desired temperature in the working areas and under the roof.
Another task of the control system is to maintain the correct ratio of the area of supply vents to the area of exhaust vents, to keep the pressure neutral zone inside the building at the desired level. This is important for fire reasons and so that supply and exhaust vents do not interchange their functions.
The added value of automatic control is the ability to remotely monitor the ventilation system in the hall. In addition, temperature sensors and sensors of the difference in pressure between the air inside and outside the hall usedfor control, give data, the archiving of which can be used to analyze energy consumption and events unusual for production.
All of the above ventilation situations in the building can be predicted and calculated using the nv-calc program. The choice of control criteria dependson the type of production and the priorities adopted for the comfort of people and the proper operation of equipment.
For designers of natural ventilation, nv-calc is a convenient tool for creating guidelines for control. It is enough to make calculations for different outdoor temperatures and indicate which air intakes and vents should be open and which closed at a given temperature to avoid, for example, possible freezing of piping systems in winter.