Air Changes Per Hour

Below is a list for average air-changes per hour (ACH) required to properly ventilate different building types. ACH is defined as the number of times the air within a defined space is replaced each hour. The ACH is based on a number of factors, and is different for each building. However over the decades that we’ve been designing ventilation systems, we’ve come to use these ranges and averages to help make some quick calculations.

Read on to find the ranges, and average ACH for more than 30 common building types.

Building Air Changes per Hour Chart

Building Type ACH RangesAverage ACH
Beater Room3030
Boiler Room30 – 6045
Bottle Pasteurizing20 – 3025
Box Annealing2020
Breweries Fermenting Room20 – 3025
Compressor15 – 2017.5
Dye Houses10 – 1512.5
Electric Furnace60 – 12090
Engine Room3030
Forge Shop3535
Foundry – Core Rooms40 – 6050
Foundry – Cupola Building30 – 4035
Foundry – Moulding Section20 – 3025
Foundry – Pouring Section20 – 3025
Galvanizing Room15 – 2017.5
Gas Producer Building10 -2015
Generating Room2020
Glass Furnaces60 – 12090
Glass Plant30 – 6045
Heat Treating Room60 – 12090
Keg Washing & Storage8 – 1210
Machine Shop10 – 1512.5
Oil Refineries – Pump House15 – 2017.5
Packing, Meat – Slaughter House5 -107.5
Packing, Meat – Smoke House3030
Paint Spray Area60 – 9075
Paper Mill2020
Pickling – Continuous10 – 1512.5
Pickling, Open Type4040
Steel Furnace Building4545
Sugar Mill – Main Building15 – 2017.5
Sugar Mill, Battery and Press1515
Textile Mill10 – 1512.5
Transformer Room3030
Turbine Room, Electricity1515
Warehouse4 – 54.5
Zinc Smelting Building6060
Air Changes Per Hour Table by Moffitt

Finding Air Changes Per Hour

Moffitt has been using this table for decades. Our ventilation design team can give you a quick estimate for your building ventilation just using the numbers above. ACH is used in the equation: ACH=60Q/Vol

where:

  • ACH = number of air changes per hour
  • Q = flow rate of air in cfm
  • Vol = volume L × W × H, in cubic feet

Moffitt Can Help You Find Your Air Changes Per Hour

Moffitt can help you find the Air Changes per Hour for our plant. We can do either an estimate using the info above or a more accurate reading with a site visit by one of our District Solutions Providers. Fill out the form today to find your building’s ACH.

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