What is the difference between ventilation and a draft?

[WoodlandWoman]

Ventilation is the exchange of fresh air from outside, with "used" air already inside the coop. At it's most basic level, ventilation brings in oxygen and gets rid of carbon dioxide. We all know what happens to life forms in a sealed plastic bag. It can also help you get rid of excess humidity, excess heat or dust and ammonia, especially if you have a litter management issue. How much ventilation you need can change, from season to season. How densely your chickens are housed, how you manage your litter, the outside humidity levels, outside temperatures and wind levels can all have an effect on this. That's why having options for how many and which ventilation openings you want open at different times is so good.

A draft is air movement that is blowing on a chicken. A light breeze in hot weather can help keep them cooler. A draft in extremely cold weather is a problem. It can cause a wind chill effect on their exposed flesh, just like it does with people. It's bad for their combs and wattles. Chickens have lots of feathers to insulate their bodies, but if air is blowing on their feathers and ruffling them at all, it releases that body heat.

Air can move in different ways in a coop. Warm air rises, cold air sinks. You will have an air exchange from a lower opening to a higher opening because of this. The highest openings in the coop are especially good for letting out excessive summer heat, warmer air that holds more humidity in the winter or just to help gently circulate air through the coop.

Air can also be moving because of wind blowing into the coop. The air will be coming in an opening from which ever direction the wind is blowing, with that. Having an opening on the other side of the coop will increase this air flow. Having the openings on the opposite side closed, will reduce the flow. Which one is better may depend on whether you are trying to cool a coop in a 110 degree day or manage a coop when it's -30 degrees.

The easiest way to figure out potential drafts is to imagine (or use a real one) a string going from one opening in the coop, to another. That's where your potential drafts will be. It might be between a vent and a window, between two windows, between two vents, between a vent and the pop hole door, etc. Place your roost so those strings aren't intersecting it. Try not to have these strings going straight through the floor area that the chickens are using during the winter days.

I think it was easier for people to understand passive ventilation and drafts in earlier times. Before everything was air conditioned. Before they built buildings with windows that don't open.

 

[elmo]

Quote:
Personally, I think that kind of "shed style" coop is the best design from the standpoint of ventilation, as well as being a very easy roof to construct. With vents on the top of the high and low walls you get good cross ventilation, and as you noted you can easily shut down the low vent for winter. If you're not making this a "walk in coop," just be sure that it's tall enough so that the high vent is well above chicken height on the roost.

 

[RoeDylanda]

Thanks for all the help! The prevailing winds are tough to figure out because the site it is semi-protected by a steep hill on one side and the house on another-- they're a short distance away but enough to disrupt air movement. I'm going out and putting a couple of sticks in the ground with a string between, and I'll tie little yarn streamers on and just see which way they go!

I get the physics of drafts, but with a 4 x 6 x 4-5 ft coop it's hard to scale down!

Thanks again, this forum is extraordinary!

[Edited to fix typos]

 

[Rocky Top Chick]

We have found that if we leave the people door open during the day the temperature in the coop stays warmer and there is no humidity at all. We close at night, but have never had a problem.