Can you share the calculation for the airflow of the room? I'm planning to do a familiar farm.
But mine will have some swamp coolers (since my area reaches outside ambient temperature of upto 48 deg Celsius in the summer).
For 17 / 19-series Bitmain, expect up to 500cfm of expelled air per miner (credit @philipma1957).
So if you're running 20 of the above, your exhaust fans need to be capable of moving 10,000cfm (20 x 500). You should consider also that the exhaust fans may lose efficiency over time (e.g. as dust builds up on the blades) so it would be sensible practice to allow a margin on top of this (so 10,000cfm + 15% = 11,500cfm for 20 miners).
Depending on the country, the fan capacity may be quoted differently e.g. meters per minute or meters per hour - but there are plenty of calculators and formulas online to convert into cfm.