I actually have two worm bins.
The primary bin is outside, in a compost box.
The secondary bin, when in use, is stored in the closet that holds our home's furnace and water heater. I use this secondary bin from autumn through spring, taking some worms and bedding materials from the primary bin.
The main purpose of the secondary bin is a backup in case the weather kills the worms in the outside bin.
My secondary bin consists of one 5-gallon bucket lid and two 5-gallon buckets.
I drill ~1/2inch/13cm holes in the lid, and use hot glue to attach pieces of fine scouring pads over the holes. The tiny spaces in the scouring pads allow air to pass.
example of scouring pads:
The upper bucket holds the worms and bedding.
I drill ~1/2inch/13cm holes in the bottom of this bucket, and like the lid, use hot glue to attach pieces of fine scouring pads over the holes.
The tiny spaces in the scouring pads allow the "leachate" liquid to drain into the lower bucket.
The lower bucket catches the "leachate" liquid liquid that drains from the upper bin [it mostly comes from moisture in the food scraps].
I don't modify this bucket at all, it fits inside the upper bucket.
As the weather begins to get colder, I prepare the secondary bin.
It sounds funny but what I do first is smear some of the moist material from the outside bin on the inside walls of the upper bucket. (Someone told me it 'acquaints' the worms to their new home.)
Next, I add new bedding material at the bottom, then some of the older bedding material from the outside bin [again, to acquaint them to their new home.]
Then, I add the worms and enough food to get them started. I am careful not to add too much food scraps to it [because it would generate too much heat], so really most of the food scraps still go to the primary bin outside .
Finally, because the closet that hold our water heater and furnace inside bin is right next to our front door, if I want to open the bucket [to add food, check on the progress, etc.], I bring it outside and then open it. That way, if there are any flying insects or fast moving creepy crawlers when I open the lid, they aren't released in the house.
Occasionally a few worms come through the scouring pads in the lid. However they don't get but a few inches and dry out.
The other worms must realize this and stay inside the nice, warm, moist environment. In nearly 15 years, I've never had a die-off.