Air Change Cfm Calculator

The rate at which air is exchanged (in the premises) represents another method of measuring ventilation capacity & effectiveness. Air exchange rate is typically expressed in Air Changes per Hour – “ACH”. Air changes per hour can be estimated by determining the total air supplied to, and removed from, the premises “total air exchange” or the outdoor (fresh) air supplied to, and removed from, the premises “outdoor air exchange”.

This table provides suggested air changes per hour (ACH) under normal conditions based on good experince.

Assembly rooms	4 – 8	Hairdressing salons	10 – 15
Bakeries	20 – 30	Hospitals – sterilizing	15 – 25
Banks/Building Societies	4 – 8	Hospitals – wards	6 – 8
Bathrooms	6 – 10	Kitchens – domestic	15 – 20
Bedrooms	2 – 4	Kitchens # – commercial	30 minimum
Billiard Rooms *	6 – 8	Laboratories	6 – 15
Boiler Rooms	15 – 30	Launderettes/Laundromats	10 – 15
Cafes and coffee bars	10 – 12	Laundries	10 – 30
Canteens	8 – 12	Lavatories	6 – 15
Cellars	3 – 10	Lecture theaters	5 – 8
Changing Rooms Main area	6 – 10	Libraries	3 – 5
Changing Rooms Shower area	15 – 20	Living rooms	3 – 6
Churches	1 – 3	Mushroom houses	6 – 10
Cinemas & theatres *	10 – 15	Offices	6 – 10
Club rooms	12 minimum	Paint shops (not cellulose)	10 – 20
Compressor rooms	10 – 20	Photo & X-ray darkrooms	10 – 15
Conference rooms	8 – 12	Public house bars	12 minimum
Dairies	8 – 10	Recording control rooms	15 – 25
Dance halls	12 minimum	Recording studios	10 – 12
Dental surgeries	12 – 15	Restaurants	8 – 12
Dye works	20 – 30	Schoolrooms	5 – 7
Electroplating shops	10 – 12	Shops and supermarkets	8 – 15
Engine rooms	15 – 30	Shower baths	15 – 20
Entrance halls & corridors	3 – 5	Stores & warehouses	3 – 6
Factories and workshops	8 – 10	Squash courts	4 minimum
Foundries	15 – 30	Swimming baths	10 – 15
Garages	6 – 8	Toilets	6 – 10
Glasshouses	25 – 60	Utility rooms	15 – 20
Gymnasiums	6 minimum	Welding shops	15 – 30