Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 176.
Österbotten, 12/08/1732, ¶975:
In winter they work in the “pörten” with the window-holes open. So that it will still stay warm even with the windows open, they close the doors. They keep fires going unless the weather is overcast.