If you arrive here for the first time, you should know that this article takes part in a series of design considerations for cleanroom HVAC calculations. Previous considerations you should have clear to proceed with the cleanroom air balance are the following:
The Air Balance
The air balance for a cleanroom or a set of them for an individual Air Handling Unit (AHU) system is quite simple.
First of all, we can calculate the airflow supply to the room. This is obtained normally from the number of air changes required, or the heat gains of the room.
When we supply a determined amount of air into a cleanroom, some part of it will not return to the system due to the leakages. In the opposite way, it could be possible that a certain amount of air of any next overpressurized room can be infiltrated into our room. This air will be added to the air return ducting system.
Even, our room can have an outdoor exhaust, as, for example, a dedicated extraction for a washing machine. In this case, we will consider this amount of air in the same category. That means we will not add this air to the air return ducting system.
Through the leakage calculation, and the pressure requirement we can determine the minimum amount of required fresh air.
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