The nest where I live is drafty, and the weather is getting cold again. Last year I tried foam tape around the doors with the effect of making the door hard to close and still drafty. The nest didn't get above 15c in the depth of winter, so I set the kitchen temperature to 10c and left the rest off. The power bill was $150/month.
Last spring I went on a mission to get a bunch of my stuff from storage in Halifax, including a big bag of worn out clothes and fabric scraps.
Last week I cut up the toes off some old socks and sewed them end to end making longer socks. I took these socks and stuffed them with more worn out clothes. Finally I took these stuffed socks and tacked them to the drafty doors of the nest.
The outside door looses a lot of heat on the opening edge, and later I may do the same to the bottom of that door too. It turns out that the metal front door is wood on the narrow edges.
Also, the bottom room gets below zero in the winter too, and has a big gap at the bottom of the door.
Both doors work as they usually do.
Over the next few months I get to see how effective this is.
