RAW & GREEN? :
Barnabas Calder on Architecture and Energy
by Florian Urban

Form follows Fuel -or is it, Form follows Food? -Or both? In advance of COP26 -and our own specially timed ‘Climate’ issue in November, Florian Urban assesses Barnabas Calder’s new book. Its exposé of Architecture – and especially the production of its materials, steel and cement – as the worst of climate-change culprits is interesting, to say the least, in the light of Calder’s published panegyrics on Brutalism…

Architecture, like any cultural expression, is dependent on the availability of energy in any given society, and therefore architectural history can be a tool to raise awareness of fossil fuel use and take action against climate change. This, in a nutshell, is the thesis of Barnabas Calder’s book, Architecture: Buildings and energy from prehistory to the present, and this is what makes it one of the most significant architectural publications in recent years. Set up as a textbook that introduces important periods and buildings in history, the book at the same time brings forward a narrative that has often been neglected: the inherent energy-dependency of architecture.

Calder, who teaches history of architecture at the University of Liverpool, convincingly shows how increases in energy availability sparked progressive waves of architectural production and innovation. One of such examples was the conquest of Egypt after 31 BC (p. 78-85), which brought one of the Mediterranean’s most fertile regions under Roman control and over the following centuries supplied the Roman Empire with large amounts of grain. The rise of imperial Roman architecture, according to Calder, was a direct consequence of the new food supply. In a pre-modern agricultural society, where typically over ninety percent of the population toiled for mere subsistence, more surplus grain meant that more people could be freed from agricultural labour and, for example, work in construction. This was the precondition for the highlights of Roman architecture, including the Pantheon (ca. 113 AD) or the Baths of Caracalla (ca. 212 AD).

But Calder does not merely focus on the Western world, but gives a balanced narrative that avoids Eurocentrism and spans diverse cultures and regions. These include the Persian Empire (Chapter 3), different Islamic societies (Chapter 5), as well as the diverse expressions of global modernity (Chapters 10-12). One of the most fascinating chapters is the analysis of Chinese architecture during the Song dynasty in the tenth to thirteenth century AD (pp. 77-116). Like in imperial Rome, the architectural boom of Song China was fuelled by increased energy supply—more food as a result of improved irrigation, more energy-efficient transport resulting from new roads and canals, and, to some extent, the use of fossil fuel, in this case coal, which was employed for iron production.

Calder’s book shows how the systematic and widespread of fossil fuel was the biggest sea change in global architectural history, starting in Britain in around 1600, and elsewhere in the world over the following centuries. The scale of this change is laid out in the introduction (pp. xi-xvii). Humans, as Calder points out, are weak, since steady human labour has not much more energy output than a lightbulb: about 0.075 Kilowatt-hours (kWh). A tonne of oil, on the other hand, contains 12,000 kWh and can thus replace over 150,000 hours of human labour or 19,000 eight-hour shifts. Consequently, one of the world’s largest structures built exclusively with human labour, the Great Pyramid of Giza completed around 2800 BC, took about 78 million labourer’s days to build, with thousands of people working on site over two decades. In comparison, the lifetime energy consumed by the US population around 2020, which includes energy for petrol, heating and transport, is the equivalent of 50 million Great Pyramids (p. xiii).

This energy wealth, according to Calder, accounts for some of the humanity’s greatest architectural achievements, as at the start of the twenty-first century even the more disadvantaged groups in industrialised countries enjoy a level of thermal comfort and amount of dwelling space that is unprecedented in history. But it is precisely the scale of this achievement that makes it so difficult to respond to the damages of fossil fuel consumption: the carbon emissions that carry the potential to make the planet uninhabitable.

Calder also points out that in the fossil fuel age it was first and foremost the availability of cheap thermal energy that boosted architectural production—not so much fire for heating and cooking, but rather heat for the production of basic architectural materials. For example, brick, one of the most prominent construction materials of the early modern period, is cheap and easy to produce compared to stone—but only if one has coal to fire it.

The same applies to the favourite materials of modern architecture. Iron, steel, glass and concrete all need immense amounts of thermal energy for their production.  Consequently, they were very expensive in pre-modern periods, when heat had to be gained from charcoal that was cumbersome and non-energy-efficient to produce and required large amounts of woodlands (p. xvii). Since the twentieth century, the abundance of these materials is based on cheap coal, oil and natural gas. The dilemma, as Calder points out, is that there are no processes available to produce these materials through renewable energies. The steel and cement industries remain the biggest industrial contributor to climate change, with a contribution of 24 per cent and 18 per cent, respectively, of all industrial carbon emissions (p. 431).

Calder’s book is written in an engaging style, avoiding jargon and excessive use of calculations. It is therefore accessible for both architectural professionals and an interested general audience. At the same time, Calder is transparent with regard to his sources, which is an important aspect of a historical study that in light of scarce documentation to a large extent has to rely on estimations and assumptions. His mathematical baseline, the calculation in Kilowatt-hours, is clear to the non-specialist reader, and so are are his comparisons of basic processes to the energy inherent in square metres of woodland—for example 5,500 square metres for every tonne of steel (xvii). Such comparisons are convincing and underline why it would be extremely difficult to gain all the energy needed for modern construction from pre-modern sources of energy such as sustainably managed forests. 

Calder’s book also contains sobering insights about the failures of recent architecture (pp. 415-44). Despite an increasing awareness at least since the 1970s about the limits of global resources and the dangers of climate change, construction-related energy consumption and carbon emissions have massively increased in recent decades. In this respect, the modernist period of high energy consumption during the 1950s and 1960s has not been replaced by an era of ecological awareness, as many had hoped at the time. Rather, despite the declared commitment of many recent architects to the goals of sustainability and resource economy, “mainstream practice around most of the world remains stubbornly dependent on heavy fossil fuel inputs” (p. 416).

Highly energy expensive buildings include many structures that are promoted under the label of ecological awareness. One example in Calder’s book is the Bloomberg Headquarters in London, which was completed in 2017 after a design by Foster and Partners (p. 434-7). The building received the highest environmental rating ever awarded by the UK’s leading sustainability assessment scheme BREEAM and was widely praised for the reduction of heating and ventilating cost.

And yet, as Calder points, out, the calculations that lay at the bottom of this positive assessment exclusively focused on operative energy such as heating and cooling. Embodied energy was not taken into account—that is, the energy which was needed to produce the large amounts of steel, concrete and bronze employed in the construction and which would have given the building a significantly worse emissions rating. Nor did the rating even refer to the most obvious potential for carbon saving: not building Foster’s design at all, and instead preserving and renovating the 1950s office building that stood at the site before. Through such analyses of recent design in comparison to historical practice Calder’s book helps to put the state of current architectural practice in perspective.

Calder paints a vivid picture of energy-related architectural innovation. He points out how much more restricted life was in the pre-modern period, which was subjected to the “photosynthetic constraint” that almost all energy used in any given society eventually had to be gained from plants’ growth. He makes a clear statement against idealisation of pre-modern architecture or vernacular design. He stresses that historic architecture was often not sustainable at all, for example the use of timber and charcoal, which already in pre-modern times led to widespread deforestation and would have been just as damaging for the global ecosystem than modern practices if there had not been so much fewer people in the world at the time.  

Calder over the last years has made his name with insightful publications on Brutalist architecture, most significantly with his 2016 “Raw Concrete – The Beauty of Brutalism”, in which he convincingly defends the architecture of Denys Lasdun, Basil Spence and others against allegations of being inhumane or simply ugly. Against this background, his current book is a remarkably self-critical reframing of his own aesthetic preferences. Calder now points to the undeniable downside of the very Brutalist architecture that he once praised: that it relies on large amounts of energy and carbon emission and in this respect it is unsustainable. At the same time this different assessment still allows him to uphold the same policy recommendations: raw concrete buildings, like any architecture that fits its purpose, should be preserved rather than demolished—possibly for aesthetic reasons, but more importantly to prevent additional carbon emissions Over all, Calder’s book is a fascinating history of architecture, a must-read for anyone interested in the relations between energy and architecture in history, and an important contribution to the discourse on energy in light of the climate emergency.

Calder, Barnabas, Architecture: Buildings and energy from prehistory to the present, London: Penguin, 2021, 576 pp., £20 (hardcover)