Ventilation: Air Changes per Hour?

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by MomMommyMamma, Jul 19, 2010.

  1. MomMommyMamma

    MomMommyMamma Chillin' With My Peeps

    Jun 13, 2010
    West Virginia
    Nerd Alert:
    My husband, an engineer, would like to know how many air changes per hour there should be in a coop. Our coop is about 7x8x10. Thanks! [​IMG]
  2. booker81

    booker81 Redneck Tech Girl

    Apr 18, 2010
    Um, wow. LOL! Not laughing at your hubs, but that is TOTALLY something I would even think of....but that may be why I'm not an engineer!!!


    I wonder if he could calculate it from patanchickens page on Ventilation based on the size of the holes etc.

    My coop is in a 20x10 shed building, taking up 10x10 give or take. Ceiling is about 8'+. The shed door (full sheet of plywood, so 4x8 is left open, and we usually have a good 5mph breeze. The back ventilation is one 1x1' grat and three openings that are about 8'x18" total. Can he figure it from that? I can say it seems to be enough for my 17 chooks - I deep litter, there is virtually no smell and everyone likes being in there when it's hot. I also add a standing fan to help the breeze.
    Last edited: Jul 19, 2010
  3. clothdiaperingmom

    clothdiaperingmom Chillin' With My Peeps

    Feb 7, 2010
    Sweetwater, TX
    I have absolutely NO IDEA! lol...would have never thought of that!
    Maybe someone smarter then I will know??
  4. patandchickens

    patandchickens Flock Mistress

    Apr 20, 2007
    Ontario, Canada
    The only situations for which well-defined criteria exist is for giant commercial chicken barns (meat chickens, and layer batteries). For those, for ammonia and humidity removal purposes you need 4 changes per hour; for cooling in the summer it can be up to 40+ changes per hour.

    I do not believe this has much of any relevance for the home coop, though, unless you are keeping your chickens in really industrial-type conditions (very crowded and horrible).

    For one thing, amount of air exchange that's required will depend GREATLY on the number of chickens per volume of coop (yes, volume in this case, not square footage), so that more-crowded coop needs more ventilation (airflow goin' on) than a very uncrowded coop. Also, your sanitation practices make a big difference -- having droppings boards under the roosts that you clean every morning makes a BIG difference in ventilation needs, IME.

    My advice remains as per my ventilation page (link in .sig below): build LOTS of ventilation, then if you have to close some (not all!!) of it down in cold weather you certainly can. Nothing bad ever came from having too much ventilation available.

    The other reason btw that I think "changes per hour" are irrelevant for a typical home coop is that it is IMHO a very bad idea to design your coop such that it depends on forced-air ventilation, which is the only thing producing *consistant* airflow numbers. A well designed passive ventilation system (i.e. air flows on its own thru openings in walls) is much better in many ways, but actual airflow will vary with the weather etc.

    Good luck, have fun,


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