Why are vents placed at the top of coops and not bottoms?

'Cause hot air rises?

 

You want ventilation, not drafts. See my BYC page for pics of my Coop, I have eave vents at the top. I close the windows during the winter to avoid drafts. Mine has worked for over 15 years, so I must be doing something right. The vents at the top allow moisture and excess heat to exit. Even in winter, I've noticed that the Coop stays 10-15 degrees warmer than outside with all the chickens on the roost. I think my deep litter compost method also helps in the wintertime. My windows are also set in shade in the summer and with the leaves of the trees gone in winter, sunlight enters the coop, helping with daytime heat.

 

Quote:X2

 

Updrafts would not be good for the chickens....you want the moisture and ammonia out but you don't want the chickens to roost with a breeze!

 

I could be wrong about this, but I think if the vents were low you could be setting up the conditions to actually create a draft over your birds. Cool air would sink out the vents, creating an airflow downwards.

The air exiting the coop would not be the warmer air (which contains the most moisture) but the colder, dryer air. That's the opposite of what you want, ideally.

 

The issues are
#1 provide ventilation
#2 eliminate draft


Although you live up north consider the wild new weather patterns. You may very well experience unusual heat this next summer. Of course the hot air will rise no matter the temp, but I suspect your husband wants to "trap" the warmth in. I think it will be easier to keep it draft free with the ventilation at the top. Some people have one wall open to the elements even in cold climates so trapping the heat in is not so important.

I was real happy with my design that had vents at the top and vinyl coated wire on the bottom. In the colder months I cover the wire floor with shade cloth and then wood chips. It would dry out even if they dumped over their water, but it stayed draft free