They were, in some ways, the original eco homes, the blackhouses or taigh dubh – more energy efficient, it has been said, than many of the homes that came after. Built with double dry-stone walls, filled with an insulating layer of straw, earth or peat, thatched roofs to shrug off the rain and keep in heat, a central hearth, but no chimney. Back in 1990, David Bruce Walker described these fires as 100 percent efficient, by comparison with the gable hearth’s 18 to 20 percent, or the modern stove of the time, at 65 percent, and dubbed the blackhouse “the green house of the future”.

Blackhouses, like these at Gearnnan village, a museum, self-cattering cottages and historic site in the west of Lewis, would also have been homes not only to humans, but their animals. It was only in the early 20th century that they got the name blackhouse,when housing regulations changed disallowing humans and animals sharing the same roof. The byre and the home could no longer be one.

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Generations of crofting families lived in houses like these, before they moved out to the new “white houses” with hearths, sanitation, large windows and multiple rooms. homes that weren’t filled with peat smoke. It was only in 1974 that the occupants of the last of these dwellings in Gearrannan left and the black house lifestyle was over.

Even upkeep of the homes would have been hard work. The thatching and regular re-thatching of a black house roof was traditionally a communal activity – using oat or barley straw, marram grass or heather. The same materials would have been used to make ropes, which using a complex system of hanging stones, secured the thatch.

But the black house reaches back further than the 1800s. Its design was similar to those found in stone-age settlements, suggesting not much had changed in the lifestyle of the islands for millennia.

But these buildings can’t be seen in isolation. As archaeologist, Dr Mary Macleod Rivett of the University of the Highlands and Islands has put it, “We must remember that agricultural people worked outside all the time, so that for them ‘home’ was not a narrow space within walls, but an attachment to the wider land. For them, and for island people right up to my grandparents’ time, home was the whole of what they could see... this whole landscape was their home.”