Ivy there are air holes in the top of the styro and of course it comes with those little red plugs which I removed. I don't think you need any more air especially if you have a fan. The fan keeps the heat even as well so you don't end up with hot and cold spots. If you like I'll take a picture of my makeshift fan set up later.
I went out and got the birds fed and watered. Now I can't get warm! I can't stress enough how much I hate this weather. The yard looks like a lake after not a drop all summer.
Hawkeye my DH bought me a pair of muck boots a few years ago. I didn't honestly appreciate them. But the last two winters I've worn them non stop out feeding and stuff. They are heavy but my feet stay warm and dry even in the coldest weather with just a pair of socks on. My granddaughter wears a pair to go work in the stables in Colorado and swears by them too. Like today mine were covered in mud and chicken poo and I hit them with the hose before I took them off. I just leave them at the back door. They are sure worth the money. I bought a pair of more fashionable shoe boots to wear but comfort and warmth in those don't compare. My boots are a bit big but that leaves me room for extra heavy socks if I want, and I tuck my jeans down in them and keep them clean and dry.
OK, while I was outside I got to thinking about viral infections. Seems to me any thing that works well for the human immune system should help the birds. I'm thinking maybe I should start supplementing feed and water with things like olive leaf extract, vitamin C, zink, L lysine etc. What do you think? Would it help?