In Britain, the age of unsustainable, carbon-intense construction began in the 17th century. Rebuilding London after the 1666 Great Fire produced about 300,000 tonnes of CO2 from coal burned to bake its half-billion bricks and to calcine the lime for their mortar.
Evolved for a low-energy society, blackhouses maximised the comfort of their residents within the tight confines of their energy resources. Inhabitants typically lived a subsistence lifestyle reliant on small grain fields, cattle husbandry and a little fishing. Domestic comfort was basic by modern standards but satisfied the fundamental human needs.
The circa 20m² central space around the hearth was both kitchen and living room, used by six people or more for cooking, crafts, socialising and storytelling. It was flanked by sleeping alcoves and the byre. The heated room constituted an island of dry warmth after windswept, often rainy days caring for cattle, tending vegetable plots, working the land, or harvesting fire fuel. Trees were too scarce and slow-growing to furnish fuel, but peat was abundant. Oral history suggests that to provide a year’s heat for one blackhouse took two to four weeks of hard work, cutting peat by hand using a tairsgeir (peat knife), then piling it to dry.
Modern volume housing insulation systems, with their tendency to serious failures and a polluting, carbon-intense start and end of life, compare poorly with building smaller dwellings in sustainable local materials such as straw, thatch and turf. Relying on good insulation and body warmth with minimal additional energy input has to be a necessary goal for future construction.
Barnabas Calder is senior lecturer at the University of Liverpool, and head of the Architectural and Urban History Research Group. He is the author of Architecture: From Prehistory to Climate Emergency.
In addition, we must push governments, national and local, of any party, to enact and uphold powerful legislation and tax regimes to encourage retrofit, to monitor and restrict embodied carbon, to enshrine reparability and re-use, and to enforce limits on operational energy measured by post-occupancy testing, rather than by optimistic pre-construction modelling.
Over 20 per cent of modern UK domestic energy consumption is for things other than heat; without the barrage of gadgets that characterise the contemporary interior, the blackhouse had no comparable energy consumers.
The elegant Georgian brick façades and generous glazed sash windows so beloved of ‘traditionalists’ were, from a carbon point of view, as inherently unsustainable as the notoriously wasteful steel-and-glass boxes of the mid-20th century or the suburban homes of the present – part of the same architectural tradition as Cumbernauld and Brasilia.
Building range
Like many buildings of today, it was not meant to last, as the inhabitants usually did not own the land they worked and were frequently forced to resettle by landlords. Arnol residents had to move their village three times between 1795 and 1853. But, in contrast with contemporary construction, the blackhouse was reparable from any level of neglect and decay, or could be dismantled for re-use. If abandoned, its thatch and mortarless fieldstone walls returned into the soil.
Learning from Lewis
When the whole or parts of contemporary buildings come to the end of their life, they are typically hard to dismantle and re-use, some parts going for energy-hungry recycling, others being ground up by powerful machines for use as low-value bulk material, and some going to landfill. A blackhouse shows circular economy to perfection.
From Donald Trump’s executive order on public buildings to the UK’s ‘Living With Beauty’ report, national architectural debate in Britain and the USA is wearisomely prone to restage 1980s battles between lovers of Modernism and those who want new buildings to pay cumbersome tribute to Classical architecture. In the face of the climate emergency, it’s time to say ‘a plague on both your houses’ – and, for that matter, on Victorian and Georgian architecture, too.
If operational energy is higher in contemporary volume housing, today’s embodied energy is in another league. The Winstone’s cavity walls are made of aerated concrete blocks with a fired brick outer skin. It is roofed in fired tile and sits on sturdy concrete foundations.
On the almost treeless Outer Hebrides, even wood was restricted to the most essential building elements, such as trusses, doorframes and doors. Iron, one of the most energy-intensive materials of the pre-modern age, was used only where its technical properties were irreplaceable, for example for the slabhraidh, the chain and pot-hook that hung over the hearth. To save on metal, rafters and tie beams were joined with wooden pegs rather than nails, and even the door pivoted on wooden hinges.
The blackhouse offers inspiration for lower-tech ways out of climate catastrophe. High-technology proprietary systems for reducing operational energy consumption should always be rigorously interrogated by a lifecycle carbon analysis to verify that they will repay their typically high embodied carbon and difficult end-of-life disposal within very few years of operation.
Key sources for this article: Bruce Walker, ‘The Lewis Blackhouse: Green House of the Future?’ (1996). FLW Thomas, ‘On the Primitive Dwellings and Hypogea of the Outer Hebrides’ Proceedings of the Society of Antiquaries of Scotland 7 (1866-68); Alexander Fenton, The Island Blackhouse (1978); Bruce Walker and Christopher McGregor, The Hebridean Blackhouse (1996); Christopher Iddon and Steven Firth, Embodied and operational energy for new-build housing: A case study of construction methods in the UK, Energy and Buildings 67 (December 2013). Vaclav Smil, Energy and Civilization: A History (2017).
Typical new houses are bigger than the blackhouse at Arnol. Take, for example, the ‘Winstone’, designed around 2010 by David Wilson Homes, built in many locations and climates all over the UK, and marketed as a ‘truly magnificent detached family home’. The two-storey house with its decorative front gable, four bedrooms, and two bathrooms is heated with fossil fuel gas through a condensing boiler. The spaces for living and socialising are significantly larger than the estimated 20m² of the blackhouse kitchen, consisting of an 18m² kitchen with seating area, a 17m² lounge and a 9m² dining room.
Operational energy
The roof beam was slanted so that animals’ body heat could rise from the byre into the living space. A hearth in the middle of the kitchen-living room floor radiated heat to residents, its warm, smoky air hanging under the chimneyless roof. Smoke’s slow filtration through the thatch preserved the perishable reed and straw from insects and repelled the countless midges. The chimneyless interior is much nicer than it might sound; peat smoke produces a pleasant smell, rather than the choking fug of wood or coal. As a 1960s visitor put it, ‘the blackhouse is definitely the cosiest you can find’.
Modernity compares badly on transport carbon, too. Blackhouse residents walked short distances to work and worship, while most volume-built housing estates are remorselessly car-dependent, their whimsical road layouts and exurban sites militating strongly against walking and cycling. Each house has its protected parking to maximise the thoughtless ease of driving, helping its occupants to uphold the UK annual average of almost 13,000km per car.
Embodied energy
The hint of a sneer in the comparatively recent name blackhouse – contrasting it with newer ‘white houses’ kept clean by absurdly profligate chimneys – hints at a fundamental change of thinking and feeling required in our appreciation of architecture. New, shiny, white, pristine – these are the luxuries of an age rich in apparently consequence-free fossil-fuel energy.
Source:Iddon/Firth