We did not put our day olds in this thing - just FYI. We raised the chicks in the bathroom in rubbermaid bins til they started to feather out - a couple weeks. Then they went outside. We didn't get the brooder until our older chicks were about 4 weeks old, mid feb. However, we did get ice and snow the last week of February.
That being said, with a solid bottom in the inside, a good layer of pine shavings and a heat lamp, that thing was nice and toasty warm. I kept a digital thermometer in it, right under the lamp, to check the temp. The inside of the brooder is large enough for the birds to get away from the heat is they want, or to snuggle under the lamp. Also, the lamp can be raised and lowered. We also closed off the door so they couldn't go out. We also "insulated " with sheets of styrofoam, but that didn't last long. The chicks pecked at it and ate it so I took it out.
I probably checked on them 3 or 4 times a day. When it snowed, I was super worried about the temp, but they all did fine. I drove my husband crazy going out th check all my birds at 2 in the morning! We got so much heavy, wet snow that one of my coop 's roof collapsed! My poor big blue bird was not happy!!!
We moved to PA a month ago and brought the brooder with us. It has been really cold here (IM-southern-thin-blood-O) We have used the brooder the whole time. It has been in the barn, but we had taken out the solid floor and so it was just the screen stuff. We put the heat lamp in and the chicks have had no problems.
Here's a couple of photos of it -
with one door open - it's really big inside. I'm 5'5" and I can't reach the birds if they go to the back when I open the door.
Here they have eaten the "insulation"
this is outside part, the chicks are 4 week old orpingtons. they look like they are a mile away!
There is a perch in it - the polish figured it out, the turkens and orps, not so much
here you can see the mesh stuff. The polish chick is about 2 months old at this point - mid March