I know these shows aren't exact science but once i noticed the houses didn't have chimneys i started looking at other images of ancient viking/norse style abodes, and none of them seem to have chimneys in them. Possibly an oversight as every image i found was a recreation or was it? Were traditional stoves/chimneys to keep the house warm not a thing?
They had fireplaces but there was no tradition of chimneys in that era, no. What you had was a "windeye" (Old Norse vindauga), a ventilation hole with a damper, under the ridge of the roof. This word was borrowed into English as 'window'. Smoke was allowed to rise and pool under the roof inside the house and find its own way out.
Chimneys only made their (broader) entrance in Scandinavia and Finland a century or two after the end of the Viking Age, but then only in towns. In the countryside it did not start to replace fireplaces until the 18th century. For instance, in that era the Norwegian priest Erik Pontoppidan wrote (p443) about the various "Clar-Stuer" (clear cottages) versus "Røg-stuer" (smoke cottages), the latter being the older kind. (the same book that also writes of the beast kraken, who via Lord Tennyson became an American pop cultural thing) By Pontippidan's (and other's) account the smoke could irritate ones eyes, although the ventilation was regulated to keep the smoke layer above one's head. Pontippidan also claims that "of old, even the kings themselves lived in such houses, for they knew of no different" until the mid-11th century king Olaf Kyrre supposedly introduced it in Norway. But whether that story is true or not, chimneys certainly didn't become common until much later. Sweden's famous botanist of the 18th century Linneaus also wrote about smoke-cottages being particularly common in certain areas, in his travelogues from around the country.
In fact, some areas - in particular those inhabited by the Forest Finns in north Värmland and southeast Dalarna in Sweden, saw the use of smoke cottages of a kind called pirtti (Swedish pörte) well into the 20th century, here's a picture from the Skansen museum of the interior, with smoke, of an actual Forest-Finn house moved there. My own grandparents were contemporary with people in the same municipality living in such homes.
The kinds of chimneys and fireplaces traditional in England are not traditional to the Nordic Countries. Those are often very inefficient heat-wise, with a large hearth and not seldom located on the side of a building (like this). Because those were used more for cooking than providing heat. Nordic chimneys and fireplaces/stoves were invariably located in the middle of the house.
