Digital Earth: A critical exploration of the emerging field of 3D printed earth construction

Digital Earth A critical exploration of the emerging field of 3D printed earth construction

Joseph Simms

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Digital Earth A critical exploration of the emerging field of 3D printed earth construction Joseph Simms - s18183489 Digital Earth - Joseph Simms

word count: 10153

Supervised by Simone Ferracina MA(hons) Architecture Dissertation December 2021 Edinburgh College of Art The University of Edinburgh

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Acknowledgements First and foremost, I would like to thank Simone Ferracina for his dedicated input and thought-provoking insight throughout this process. His careful guidance and critical questioning have been invaluable.

I’d also like to take this opportunity to thank Moa Carlsson who’s course this year has galvanised my interest in 3D printing, and Paul Diamond, who’s helped me realise my experiments in printing clay.

Digital Earth - Joseph Simms

Finally, I’d like to thank my family, my friends, and my better half, Jess. All of whom have been a constant support throughout this process.

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Contents Abstract

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Glossary of terms

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Introduction

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Chapter 1

Digital Earth - Joseph Simms

Beginnings & Materials

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1.1. Evolution of the technology 1.2. How do 3D printers work?

1.3. 3D printed construction (3DPC) 1.4. A note on materials 1.5. A case for earth Chapter 2

Equipment & Case Studies

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2.1. Introduction to WASP 2.2. Gaia House 2.3 TECLA House 2.4 Can anyone print a house?

2.5. Digital equipment Chapter 3

Energy, Extraction & Performance 3.1. A case for cob 3.2. On site energy 3.3. Where does our energy come from?

3.4. Can we 3D print off-grid?

3.5. Earth as an insulator: comparative analysis

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Chapter 4

Structure, Scale & Durability

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4.1. The structure of earth 4.2. Can we scale up?

4.3. How durable is earth?

Chapter 5

Concluding remarks: Where and Who?

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Bibliography

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Figure References

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Digital Earth - Joseph Simms

5.1. Where can we build with earth?

5.2. Automation and labour 5.3. Final conclusions

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Abstract

Digital Earth - Joseph Simms

We are living in a world of rapid technological advancements. Via the internet, ideas are now shared and spread quicker than ever before, allowing real time global communication and accelerated technological development. These advancements are clearly observable in recent technologies such as AI, medicine and material sciences, with new breakthroughs constantly being made all around the world.

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Despite industries such as textile manufacturing having embraced automated processes since the 19th century, much of the construction industry today still relies on the same techniques that have been used for decades. The industry is largely outdated and fails to make use of automation or new digital methods on a widespread basis. In parallel to this, we are also faced by a devastating rate of climate breakdown, fuelled by the burning of fossil fuels.

Recent developments in digital fabrication offer a radical paradigm shift from traditional methods of construction, translating digital design directly into physical form. 3D printing is one technology that shows great promise for use in producing highly customised objects, digitally optimised structures and complex parametric forms. Combining cutting edge digital fabrication and the most ancient building material known to man, 3D printing of earth may offer new sustainable possibilities for the industry and put readily available natural materials at the heart of advanced digital construction. This study will examine and critically analyse the case for earth-based 3D printing, encompassing a range of existing study in the field through both academic and commercial research and projects.

Glossary of terms 3D - Three-dimensional 3DP - 3D printing 3DPC - 3D printed construction AM - Additive manufacturing CC - Contour crafting

FDM - Fused deposition modelling GHG - Greenhouse gases Sustainable - in an environmental context, the term refers to processes that cause little or no damage to the environment.

While very few processes cause zero environmental damage, in this paper, sustainable will refer to methods and practises that cause less environmental damage than widely used alternatives.

For example, travelling by bus is not carbon neutral, however, it has a lower carbon footprint than travelling by car and can therefore be classified as sustainable.

Digital Earth - Joseph Simms

CLT- Cross laminated timber

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Introduction We are facing an emergency. Human activities are estimated to have raised global temperatures 1.0°C above pre-industrial levels. At the current rate, temperatures are predicted to further increase by 0.2°C per decade, with CO2 levels at their highest in at least the last 2 million years.1 These human induced changes are already having an effect on the planet, causing heavy rainfall, droughts, tropical storms and heatwaves; leading to food shortages and loss of life. Unless drastic reductions of CO2 and other greenhouse gases (GHG) occur in the coming decades, global temperatures are highly likely to exceed 2°C above pre industrial levels by the end of the 21st century. This would lead to an increased melting of permafrost, glaciers and Arctic sea ice; in turn triggering the further release of CO2 and setting off a disastrous feedback loop of climate breakdown and extreme weather patterns.2 Such adverse changes could mean the end of life as we know it; threatening the existence of future generations and possibly leading to a sixth mass extinction.3 Buildings and construction are responsible for 39% of all global CO2 emissions.4 This is largely due to the use of materials with a high embodied carbon footprint, such as concrete,5 but also the energy used to maintain and heat buildings, which comes

1 IPPC, “Climate Change 2021: The Physical Science Basis: Summary for Policymakers: Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change” (IPPC, 2021), 4-8.

2 IPPC, “Climate Change 2021,” 10-11.

3 Jeremy Rifkin, The Green New Deal: Why the Fossil Fuel Civilization Will Collapse by 2028, and the Bold Economic Plan to Save Life on Earth (New York: St Martin’s Press, 2019), 1.

4 United Nations Environment and International Energy Association, “Towards a Zero-Emission, Efficient, and Resilient Buildings and Construction Sector: Global Status Report 2017” (Paris: IEA, 2017), 6.

5 Jonathan Watts, “Concrete: The Most Destructive Material on Earth”, The Guardian, 25 February 2019, https://www.theguardian. com/cities/2019/feb/25/concrete-the-most-destructive-material-onearth

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primarily from fossil fuel sources.6 To help avoid the worst effects of climate change, a rapid transition towards alternative sustainable materials and methods, and significantly improved energy performance is needed.

Earth has been used in construction for thousands of years. It is abundant and freely available all over the globe. 3D printing of earth radically modernises earth building techniques, allowing digital design tools to be used in parallel with this ancient material.

Chapter two outlines the equipment used in the process and presents case studies of 3D printed earth structures by Italian company WASP (see fig.1). Through a critical analysis of WASP’s methods, equipment and results, the paper goes on to explore the viability of earth 3D printing as a new sustainable method of construction.

Digital Earth - Joseph Simms

3D printing promises a shift away from long-dominant modes of mass production and associated environmental damage and towards a model of laterally distributed, localised mass customisation.7 Chapter one traces the origins and applications of this technology. Thanks to pioneers such as Charles Hull and Adrian Bowyer, 3D printing has gained widespread popularity and a diverse range of sectors are now putting the technology to use, from medicine, to fashion, to food.8 In the last two decades, principles of 3D printing have slowly begun to be developed for construction applications and the method has been successfully used to build a small number of projects. Large-scale prints have been carried out in a range of materials such as concrete, plastic and earth. However, it’s essential that material choices are carefully considered, in order to have minimal environmental impact.

Continuing to refer to the claims made by WASP, chapter three examines the energy involved in the process of 3D printing earth buildings, comparing the process to concrete 3D printing and 6 UN Environment and International Energy Agency, “Towards a zero-emission, efficient, and resilient buildings and construction sector”, 9.

7 Jeremy Rifkin, The Zero Marginal Cost Society: The Internet of Things, the Collaborative Commons, and the Eclipse of Capitalism (New York: St Martin’s Press, 2014), 107-108.

8 Claire Warnier et al., eds., Printing Things: Visions and Essentials for 3D Printing (Berlin: Gestalten, 2014).

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discussing energy sources and extractive processes. The chapter also explores the thermal performance of 3D printed earth structures, through comparison with common wall build ups.

Digital Earth - Joseph Simms

Chapter four and five challenge the real-world viability of earth 3D printing. Chapter four explores structural characteristics of the material, both in its physical properties and its digitally designed forms. Further discussion speculates on the possibility of using the method to build at larger scales and explores the durability of 3D printed cob. Chapter five examines the climates and geographies which are most suited to 3D printed earth and discusses implications of automation on construction and advantages of the speeds of the process. It concludes with a speculative discussion of the future of the technology and likely impacts.

While this piece of course isn’t a comprehensive overview of 3D printed earth, the writing touches on key areas of discussion and interest. Most academic work on this subject has focused on primary research and tests. This paper intends to capture broader and more cutting-edge developments and has therefore considered a wider range of material, including academic research, newspaper articles and commercial website content.

Figure1 3D printed earth house by WASP

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Figure 2 Earth structure printed at the Institute of advanced architecture of Catalonia

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Beginnings & Materials A very brief history of 3D printers The invention of 3D printing is generally credited to Chuck Hull, who, in 1986, successfully patented stereolithography (SLA) printing and established 3D Systems, the world’s first commercial 3D print manufacturer.9 Hull’s printer used a concentrated beam of UV light to draw shapes into photopolymer resin, which then built up a 3D solid form, layer by layer.10 Further developments in 3D printing were quick to follow; such as the invention of Fusion Deposition Modelling (FDM) by Scott Crump, in 1988.11 Today, several types of 3D printing now exist including Selective Laser Sintering, Stereolithography, Digital Light Processing and Laminated Object Manufacturing. Most of these processes are best suited to manufacturing highly specialised and complex objects such as custom machine parts or personalised prosthetics. Furthermore, most industry standard machines are very expensive and are not able to manufacture single objects larger than 1m³. 3D printers are also used to quickly produce accurate prototypes before final products are mass produced by more conventional methods such as injection moulding.

In popular culture, interest in 3D printing has grown hugely over the last fifteen or so years. Arguably, this is down to the RepRap Project. Conceived in 2005 by Adrian Bowyer at The University of Bath, RepRap was the first open-source 3D printer, capable of self-replicating many of its own parts (see fig.3).12 The project was quickly embraced by many individuals and small companies, with creators using the open-source instructions to create their own machines and suggest tweaks or improvements. 3D printers were no longer vastly expensive machines used only for specialist industrial applications. They now began to be used by 9 Hod Lipson and Melba Kurman, Fabricated the New World of 3D Printing, (Indianapolis, Ind: John Wiley and Sons, 2013), 37-38.

10 Lipson and Kurman, Fabricated the New World of 3D Printing 73-74.

11 Christian Groth et al., “Three-Dimensional Printing Technology,” Journal of Clinical Orthodontics : JCO 48 (1 August 2014): 476.

12 Douglas Bryden, CAD and Rapid Prototyping for Product Design (London: Laurence King Publishing, 2014), 141-142.

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small companies and inspired designers. This led the creation of companies such as MakerBot, in 200913 and Formlabs, in 2011,14 who began manufacturing affordable desktop printers for the mass market. A wide range of home printers has since flooded the market, at increasingly affordable prices.

Digital Earth - Joseph Simms

Figure 3 “Dawin”, the first generation of RepRap printers

13 Matthew B. Stokes, 3D Printing for Architects with MakerBot, (Birmingham: Packt Publishing, 2013), 28.

14 Formlabs, “About Us,” Formlabs, accessed 5 December 2021, https://formlabs.com/uk/company/.

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How do 3D printers work?

Digital Earth - Joseph Simms

Whichever type of printing process is used, there are a few distinctive characteristics of the 3D printed process. Firstly, the process starts with a 3D file. This may either be modelled from scratch, downloaded from a sharing site, or purchased from an online marketplace.15 Files must be ‘watertight’, meaning that they are modelled as solids, before being converted to an STL format; a file format developed specifically for 3D printing.

Because of the layering process of 3d printing, the model must then be ‘sliced’ into layers that can be individually printed. Layers are unusually aligned on a flat horizontal-plane. However, there may be some instances where layers are deliberately sliced in a non-parallel fashion in order to achieve structural strength of complex forms.16 For example, in 2021 Zaha Hadid Architects and Block Research Group completed the Striatus bridge in Vienna. The bridge, constructed of modular 3D printed concrete components, is printed in non-uniform layers in order to achieve maximum compressive strength without the need for reinforcement (see figs.4-5).17 Before a component is printed, the STL file must first be transferred into G-code, which defines the path of the printer, the speed, the rate of material extrusion, as well as other possible commands such as the temperature of the print material or the rate of the cooling fan, depending on which type of machine is being used (see fig.7).

15 Warnier et al., Printing Things: Visions and Essentials, 9.

16 Lipson and Melba, Fabricated: The New World of 3d Printing, 77-80.

17 Block Research Group, “Striatus - 3D Concrete Printed Masonry Bridge, Venice, Italy, 2021,” BRG, 2021, https://block.arch. ethz.ch/brg/project/striatus-3d-concrete-printed-masonry-bridgevenice-italy-2021.

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Figure 4 Piece of the Striatus bridge being printed off site, in a non-uniform fashion

Figure 5 The finished Striatus bridge , by Zaha Hadid Architects and Block Research Group

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3D Printed Construction (3DPC)

Digital Earth - Joseph Simms

An internet search of ‘additive construction’ brings up pages full of images of 3D printers and layered concrete. The word ‘additive’ generally now refers to 3D printing. However, the core concept far pre-dates the digital age. Some of the most ancient building techniques such as mud brick walls or the simple stacking of stones can be categorised as additive. Very few buildings are constructed in an entirely subtractive fashion besides those carved directly into rock.

In the process of making, a material must be sorted, purified and prepared, with some inevitable waste. Although bricklaying is conventionally seen as additive, through a critique of the hylomorphic model, Gilbert Simondon questions this categorization. While the hylomorphic model may account for the clay of which the brick is made (matter) and the mould in which it is pressed (form), this is just the end of two chains of production, each object first having to come through a process of refinement, extraction and subtraction (see fig.6).18 Using Simondon’s thinking, very few if any processes are without waste or subtraction when traced through their respective material chains. This view is true even of 3D printing (often referred to as additive manufacturing), where materials must first be refined before use, as well as the manufacture of the printer itself not being without waste.

In construction, the use of additive manufacturing (AM), which will now be used to refer to the contemporary principle of digital additive manufacturing, can be traced back to the work of Behrokh Khoshnevis at the University of Southern California (USC).19 Khoshnevis’ method of Contour Crafting (CC) involved using a large-scale concrete extruding machine, attached to a gantry crane. The machine worked similarly to an FDM printer, in 18 Gilbert Simondon, “# PHILOSOPHY /// Form & Matter: Gilbert Simondon’s Critique of the Hylomorphic Scheme Part 1,” The Funambulist Magazine, 8 December 2012, https://thefunambulist.net/ editorials/philosophy-form-matter-gilbert-simondons-critique-of-thehylomorphic-scheme-part-1.

19 Behrokh Khoshevis, Additive fabrication apparatus and method, United States US5529471A, filed 3 February 1995, and issued 25 June 1996, https://patents.google.com/patent/ US5529471A/en.

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that liquid material was printed onto a base plate, or in this case directly onto the ground.

Other university research groups have also pioneered work in the 3DPC sector, such as ETH Zurich, Loughborough University, TU Eindhoven (see fig.8), the Institute for Advanced Architecture of Catalonia (IAAC) and Cardiff University.

Digital Earth - Joseph Simms

However, the work being done in the commercial sector is arguably equally as significant. In 2014, the Chinese company WinSun printed ten basic homes in 24 hours, demonstrating the practicality and speed of the 3DPC. The company used a large gantry-style printer and high-performance mortar, claiming that the houses cost less than $5000 each to manufacture. The house was constructed in components, each printed off site before being transported and assembled.20 The same company was commissioned in 2016, to print an office building for the government of Dubai (see fig.9). The components were all printed at WinSun’s factory in China, before being shipped to Dubai.

Additive manufacturing of concrete can be more sustainable than traditional methods due to reduced material usage, as a result of hollow wall sections as opposed to solid concrete walls. Local manufacture would reduce emissions from 3DPC further.

Figure 6 The making of a brick

20 Camille Holt et al., “Chapter 17 - Construction 3D Printing,” in 3D Concrete Printing Technology, ed. Jay G. Sanjayan, Ali Nazari, and Behzad Nematollahi (Butterworth-Heinemann, 2019): 353.

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Structural optimisation

3D model

Digital Earth - Joseph Simms

STL File

Grasshopper

G-codes may be written in Grasshopper

Rhino 3D

Parametric design

Optional additional stabilser

Water Subsoil

Slicing

Straw G-code Raw materials Extrusion rate Print speed

Print path Mixing Process

3D Printer

Print mix Mixing machine such as cement mixer or wet pan mill

Print

Final Object

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Figure 7 The process of 3D printing earth

Digital Earth - Joseph Simms

Figure 8 ‘Project Milestone’, a 3D printed house developed by TU Eindhoven

Figure 9 Office of the Future in Dubai by WinSun

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A note on materials

Digital Earth - Joseph Simms

In the development of 3DPC, concrete has been by far the most used material since it was first proposed in the CC method.21 However, the use of concrete in construction seems to be at odds with a sustainable future of housing, since concrete production accounts for between 8 and 9% of all anthropogenic global CO2 emissions.22 Furthermore, the mining and extraction of cement and aggregates devastate natural habitats.23 Concrete, like earth, has a long history in construction. Concrete, in a form made with volcanic ash, was used by the Romans in many buildings, including the Pantheon (see fig.10).24 Following the collapse of the Western Roman Empire, the material fell into disuse for around 1400 years. The material was rediscovered and quickly put to use during the first industrial revolution, this time reinforced with steel, making it the perfect material for the vast growth of infrastructure during the period. By 1921, an estimated 40,000 reinforced concrete structures had been built.25 Concrete production is now a highly commercialised and globalised industry, with little relationship to locality. While concrete is used in every country, raw materials are often shipped long distances, producing further emissions. The extraction of sand, a key component of concrete, is the largest mining operation on the planet, making up around 85% of all mineral extraction.26 Around the world, sand is being dredged, mined and 21 Bajpayee Aayushi et al., “In Situ Resource Utilization and Reconfiguration of Soils Into Construction Materials for the Additive Manufacturing of Buildings,” Frontiers in Materials 7 (2020): 2.

22 Sabbie A. Miller, Arpad Horvath, and Paulo J. M. Monteiro, “Readily Implementable Techniques Can Cut Annual CO2 Emissions from the Production of Concrete by over 20%,” Environmental Research Letters 11, no. 7 (July 2016): 4.

23 Watts, “Concrete: the most destructive material on earth.”

24 Michael W. Fazio, Marian Moffett, and Lawrence Wodehouse, A World History of Architecture (London: Laurence King, 2013), 119-120.

25 Fazio, Moffett and Wodehouse, A World History of Architecture, 419-420.

26 Fred Pearce, “The Hidden Environmental Toll of Mining the World’s Sand,” Yale Environment 360, 5 February 2019, https://e360. yale.edu/features/the-hidden-environmental-toll-of-mining-theworlds-sand.

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simply taken, often illegally, before being shipped off to be used in vast construction projects abroad, all with significant deleterious environmental impacts.

While sand may seem vastly abundant, not all sand is appropriate for construction, and may therefore need to be imported depending on the location. For example, desert sand becomes rounded and smooth as a result of wind erosion, and is therefore useless for construction.27 While less damaging than cast concrete, as a result of more efficient material use; 3D printed concrete does not provide a rapid reduction in environmental impacts . 28

However, despite rhetoric about the potential of recycling, the reality is often a downcycling of materials, where they are broken down and no longer of sufficient quality for their original use.

Plastics may be continually recycled, each time going through an energy intensive process and ending up as a lower quality product until they eventually end up in landfill.31 Due to the use of structural plastics being unprecedented in construction, paired with the use of concrete and the reality of recycling materials; with the current technology, 3D printing plastic buildings is unlikely to offer practical and sustainable housing solutions.

Digital Earth - Joseph Simms

Concrete isn’t the only material which has been used to 3D print buildings. In 2014, Dutch architects DUS printed an “urban cabin” in the centre of Amsterdam out of PLA bioplastic (see fig.11).29 However, the “cabin” is only 8 sqm, with some of the lower portion of the hollow plastic tessellations being infilled with concrete to secure the structure, due to PLA’s light and flimsy nature.30 DUS claims that the structure can be broken up and recycled for further use.

27 Pearce, “The Hidden Environmental Toll of Mining the World’s Sand.”

28 Aayushi et al., “In Situ Resource Utilization and Reconfiguration of Soils Into Construction Materials for the Additive Manufacturing of Buildings,” 2.

29 DUS Architects, “Urban Cabin,” DUS Architects, 2015, https:// houseofdus.com/project/urban-cabin/.

30 DUS, “Urban Cabin.”

31 Samantha MacBride, “Does Recycling Actually Conserve or Preserve Things?,” Discard Studies, 11 February 2019, https://discardstudies.com/2019/02/11/12755/.

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Figure 10 The Pantheon, an early predecessor to modern concrete construction, as painted by Giovanni Paolo Pannini in 1747

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Figure 11 ‘Urban Cabin’, in Amsterdam by DUS Architects

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A case for earth

Digital Earth - Joseph Simms

It is estimated that between one third and a half of the world’s population - approximately three billion people, live in buildings constructed of earth.32 Mud and earthen construction has been used for around 9000 years with evidence suggesting mud bricks were used between 8000 BC and 6000 BC in Russian Turkestan, while remains of rammed earth foundations in Assyria date back to 5000 BC.33 Earth has been used as a building material by ancient cultures all over the world, from mud brick walls in Iron Age Germany, to the ancient city of Bam, Iran (see fig.12).34 Despite the huge number of earth and mud buildings around the world, such vernacular building systems are often viewed as primitive, unsophisticated, or simply outdated. Brown and Maudlin suggest that this may be to do with the fact that such ‘vernacular’ building types have generally evolved outside of the fold of academia and may have been seen to fall outside more formal architectural practice.35 Vernacular earth construction methods are becoming less common, due to it being a slow and highly labour-intensive method of construction, with polluting and resource intensive methods such as concrete block construction often proving quicker and cheaper. Therefore, digital printing of earth may prove to be vital in re-promoting the use of this ancient building material within a contemporary context.

32 Ronald Rael, Earth Architecture (New York, N.Y: Princeton Architectural Press, 2009), 9.

33 Gernot Minke, Building with Earth: Design and Technology of a Sustainable Architecture (Basel: Birkhäuser, 2013), 11-12.

34 Minke, Building with Earth, 11-12.

35 Robert Brown and Daniel Maudlin, “Concepts of Vernacular Architecture,” in The SAGE Handbook of Architectural Theory (London: SAGE Publications Ltd, 2012), 342.

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Figure 12 The Mud city of Bam, Iran

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Equipment & Case Studies

Digital Earth - Joseph Simms

Introduction to WASP World’s Advanced Saving Project (WASP) is an Italian 3D printing company based in Massa Lombarda near Bologna. Founded in 2012, WASP is a manufacturer of 3D printers for all scales and uses, as well as a research group focusing on sustainable development.36 The company uses the profits from the commercial sale of their printers to fund research and development of new products, with the aim of creating sustainable machines that benefit everyone. WASP also aims to develop systems to build what they call “zero-mile homes”, meaning that all construction materials can be found directly adjacent and around the site, eliminating the need for transport and shipping of construction materials and in turn reducing emissions.37 WASP is a commercial organisation and not an academic institution or publicly funded body. This means that any information which is published on their website is relatively limited and is generally a positive promotion of their methods; rarely critically analysing or explaining the processes involved. All publicly available information about WASP’s earth printed projects is limited to what one can already find on their website.38 However, WASP are industry front-runners in the implementation and testing of earth 3D printing. WASP have printed two homes, both of which have utilised their CraneWASP printer. CraneWASP is a large scale, modular printer system which relies on a large frame with a central rotating arm to which the extruder is attached (see fig.14). The 4m high structure is arranged in a triangular support layout, allowing multiple machines to print simultaneously, if arranged in tessellating patterns. Each machine is capable of printing a structure of 6.3m diameter by 3m height. However, the central extruder support does (presumably) mean that it’s 36 WASP, “Massimo Moretti - Ceo of WASP,” WASP, accessed 5 December 2021, https://www.3dwasp.com/en/massimo-moretti/.

37 WASP, “About Us,” WASP, accessed 5 December 2021, https:// www.3dwasp.com/en/about-us/#manifesto.

38 WASP Press Team, Email to author following information request, 12 October 2021.

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impossible to print a fully capped structure such as a dome and another component would be required to cover the central area of the roof, as has been the case with both of the WASP’s projects using the machine.

Using the current technology, only small single storey buildings can be constructed. However printers may run simultaneously in a tessellating pattern, meaning that in theory there is no limit in the floor area of the print.

Digital Earth - Joseph Simms

Figure 13 CraneWASP printer system, capable of using several printers simultaneously due to the tessellating frame

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Gaia House The first project to use the CraneWASP was the Gaia house, built in 2018.39 Gaia is a small dwelling, printed in 10 days from a mix of raw earth from the site, chopped rice straw and rice husk. The wall structure utilises geometric patterns to optimise structural strength while minimising material use and allowing cavities to be filled with insulating rice husk (see fig 14). This project demonstrated the potential to re-use agricultural waste in the 3DPC process. WASP believe that it “is possible to concretely conceive new economic scenarios in which one hectare of cultivated paddy field can become 100 square metres of built area.”40 Combined with the use of local raw earth materials, the system shows promise to deliver new construction techniques to rural areas while also making productive use of agricultural byproducts. Using agricultural waste in earth construction has been practised for millennia and is known as adobe or cob construction.

Traditionally straw is mixed with clay soil to give it structural strength then built up in layers, not too dissimilar to the earth printing process, bar the use of digital tools. The Gaia house uses 3D printed elements for the wall pieces only, with the roof being built of timber due to earth construction only having strength in compression (see fig.15). Notably, the roof also overhangs above the earth walls to protect them from coming in direct contact with heavy rain, which may erode the earth.

39 Alberto Chiliusoli, “The First 3D Printed House with Earth | Gaia,” WASP, 29 September 2018, https://www.3dwasp.com/casastampata-in-3d-gaia/.

40 Chiliusoli, “The First 3D Printed House with Earth | Gaia.”

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Figure 14 Rice husk being poured into the wall geometry as insulation, in the Gaia House

Figure 15 The finished Gaia House, with overhanging roof to provide protection from rain and shade

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TECLA House In 2021, building on the lessons learned from the Gaia house; WASP put their system to the test again. Designed in collaboration with Mario Cucinella Architects, TECLA is claimed to be the world’s first fully 3D printed earth house. The structure takes a double dome form, meaning that the walls, roof and structure are all printed as a single component, using a local earth mix (see fig.16). However, because of the support structure, a full roof is not able to be constructed and a skylight is therefore used to complete the structure. The TECLA project was used to demonstrate the full capabilities of the CraneWASP system, using two machines, printing the same structure simultaneously (see fig.17.). The team at WASP believe that TECLA may prove a major landmark in the future of local, sustainable housing solutions.41 Commenting on the project, Mario Cucinella said: TECLA responds to the increasingly serious climate emergency, to the need for sustainable homes and to the great global issue of the housing emergency that will have to be faced.42

41 WASP, “3D Printed House TECLA,” WASP, accessed 5 December 2021, https://www.3dwasp.com/en/3d-printed-housetecla/.

42 WASP, “3D Printed House TECLA,”

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Figure 16 TECLA house by WASP

Figure 17 The TECLA house being printed with the CraneWASP system

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Can anyone print a house?

Digital Earth - Joseph Simms

While WASP’s earth houses are impressive, one must consider that their structure was built as a one-off project under ideal conditions, with the help of a highly skilled team. At the current moment, it’s inconclusive whether this same approach could really be applied to provide cheap, sustainable housing around the world, as WASP and Mario Cucinella claim. In order to comprehend the real-world impact that such projects may have, it’s integral that further case studies are not only built, but also inhabited, in different regions of the world. The idea of simply printing a house, though it may sound straightforward, is in fact far more complex and difficult:

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Through conducting my own tests with a WASP 2040 clay printer, the process proved to be highly technical, with many factors such as the extrusion pressure, the water content of the mix and the extrusion speed all affecting the quality of the print. The process of 3D printing clay can be broken down into three main processes: preparation of clay, machine set up, and finally printing. Each stage requires careful consideration and an element of skill. In reproducing a 1:100 wall section of WASP’s Gaia house, (see figs.

18-22.) the printer had to be restarted several times due to initial failures such as the mix being too dry .

Even in the controlled context of a workshop, the reality of 3D printing is that things may not always go to plan, models may collapse, or extruders may fail. Printing in wet earth only adds a huge number of technicalities to these difficulties. Large scale 3D printing must also consider air temperature and humidity, further adding to the challenges and corresponding skills involved.

Digital Earth - Joseph Simms

Figure 18 WASP 2040 clay 3D printer in Edinburgh College of Art workshop

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Figure 19 Section of the Gaia house wall, modelled on Rhino 3D before being converted to STL format for slicing, then converted to G-code using Simplify3D

Figure 20 Printing clay mix using the WASP 2040 clay

Figure 21 Failed print due to mix being too dry, causing the extruder to become clogged and the print to crack

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Figure 22 Making a new mix with higher moisture content to avoid cracking. While WASP provide recommended recipes for the mix, the reality of the perfecting mix ratios often comes down to experience and an innate tactile understanding

The final structure felt durable and strong due to the geometric qualities and curved surfaces of the model

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Figure 23 Final successful print, Gaia house wall section 1:100

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All the printers created and produced by WASP are commercially available to anyone. The CraneWASP printer starts at €132,000 or is available as part of a “Maker Economy starter kit”, a single shipping container carrying a range of 3D printers and all the necessary tools to accompany them, designed to allow selfsufficient production of a full house and furniture.43 Currently, WASP is the only producer of large-scale earth printers for commercial sale. While the cost of the set up seems eyewateringly high, it’s worth considering a couple of things. Firstly, the printer is allegedly able to make use of on site, and therefore free soil, meaning that in theory, the material cost is marginal with the addition of a binder such as agricultural waste or straw.

Secondly, it is likely that the price will dramatically fall over time as more printers are purchased and other companies start entering the market.

We have already seen this rapid price plunge play out over the last two decades with conventional 3D printers; it therefore seems conceivable that the emerging technology of construction 3D printing will follow suit. The first “low-cost” 3D printer was put onto the market in 2002 with a price tag of $30,000. Today we see high quality printers being sold for as little as $1,500 while entry levels machines may only cost $200.44 It’s almost inevitable that as the technology becomes more widely used the price will correspondingly fall, making it more financially accessible.

In Jeremy Rifkin’s The Zero Marginal Cost Society, he proposes a vision of a world in which decentralised and renewable energy networks provide power for a world where consumers print their own goods at home, no longer reliant on mass production and corporate industry.45 It’s not envisioned that everyone will ever own a construction printer and print their own homes. However, if such printers were distributed and shared between communities, in the same spirit of community fab-labs, collective access to such a machine may prove an invaluable resource to allow sustainable construction, using local, natural materials.

43 WASP, “Maker Economy Starter Kit,” WASP, accessed 5 December 2021, https://www.3dwasp.com/en/maker-economy-starter-kit/.

44 Rifkin, The Zero Marginal Cost Society, 90.

45 Rifkin, The Zero Marginal Cost Society, 89-108.

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Digital equipment

Digital manufacturing gives us some advantages over traditional techniques. The use of parametric design tools such as Grasshopper allow us to design forms that are vastly more complex than could be achieved by hand, allowing the designer to break free from the orthogonal constraints of traditional methods such as brick and timber, and pursue free-form curvilinear forms that mimic natural patterns and structures. More importantly, structure and forms could be precisely optimised to offer maximum strength with minimal material usage with the help of evolutionary finder tools (see fig, 25).49

Digital Earth - Joseph Simms

Arguably, the idea of printing earth at construction scale, is predated and influenced by the development of clay 3D printers. Ever since the RepRap project published open-source instructions to build a 3D printer, artists and designers have been constructing their own clay extrusion machines.46 For example, in 2010 design group Unfold Studio and Tim Knapen exhibited their self-produced clay printer in the exhibition: “L’Artisan Électronique”, held in the Z33 gallery in Hasselt, Belgium (see fig.24).47 The exhibition aimed to blur the lines between craft and technology, featuring a digital potter’s wheel. Visitors were encouraged to craft a vase by passing their hand above the laser controlled potter wheel, in the same gesture that traditional pottery turning would require. The form is then encoded into a 3D file before being printed in clay.48 This synergy between the contemporary digital and traditional craft is the same spirit that is embodied in earth printing, giving new and accurate forms to long used materials.

A 2020 Study found that compared to traditional cob construction, the 3D printing of cob used 34% less material.50 Beyond 46 Unfold, “Ceramic 3d Printing,” Unfold Design Studio, 12 December 2009, http://unfold.be/pages/ceramic-3d-printing.html.

47 Warnier et al, eds, Printing Things, 56.

48 Warnier et al, eds, Printing Things, 56.

49 Mohamed Gomaa et al., “Feasibility of 3DP Cob Walls under Compression Loads in Low-Rise Construction,” Construction and Building Materials 301 (27 September 2021): 9-10.

50 Haseem Alhumayani, Mohammed Gomma, Veronica Soebarto, and Wassim Jabi, “Environmental Assessment of Large-Scale 3D Printing in Construction: a comparative study between cob and concrete,” Journal of Cleaner Production 270 (2020): 5.

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aesthetics and structure, using digital and generative design to create complex parametric forms with high surface areas may aid the thermodynamic performance of a thermal mass, allowing structures to more effectively regulate heat passively.51

Figure 24 Craft meets digital in “L’Artisan Électronique” by Unfold Studio

51 Dana Cupkova and Nicolas Azel, “Mass Regimes: Geometric Actuation of Thermal Behavior,” International Journal of Architectural Computing 13, no. 2 (1 June 2015): 191-192.

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Figure 25 Complex geometric wall structure, 3D printed in mud. Digital design allows for less material usage, structural optimisation and opportunities to improve thermal properties

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3

Energy, Extraction & Performance

Digital Earth - Joseph Simms

A case for cob Earthen buildings have been constructed for thousands of years using few tools and simple methods. Numerous methods of building with mud and earth exist, such as rammed earth, earth block and mud brick. However, cob (as it is known in the United Kingdom) bears the most resemblance to the material composition used in earth 3D printing. Cob is also known as bauge, chineh and atterati, just to name a few. In fact, cob has tens of names all from different local regions around the world, attesting to the widespread global popularity of the material.52 At its heart, cob is simply a mix of earth, water and organic fibres such as straw and hemp. Similar to the 3D printing process, cob is also built up in layers, without the use of formwork. Traditional cob structures in England were often built by agricultural workers who made use of available equipment such as forks and shovels to mix the cob before placing it on the wall and manually compacting it by standing on top of the wall (see fig.26) Sometimes animals such as cows and horses were even used to tread and mix the cob, with the addition of some manure as extra binder.53 To this day, people still use the traditional method of making cob, mixing with just a fork, or even using hands and feet. The distinct handcrafted appearance of the material is often embraced and the building process is seen as a slow, community experience, favouring the use of minimal machinery.54 However, it is very labour intensive and a widespread use of backbreaking labour is not the answer to the challenges we face.

52 Erwan Hamard et al., “Cob, a Vernacular Earth Construction Process in the Context of Modern Sustainable Building,” Building and Environment 106 (1 September 2016): 103–19, 106.

53 Linda Watson and Kevin McCabe, “The Cob Building Technique. Past, Present and Future,” Informes De La Construcción 63, no.

523 (2011), 60-61.

54 Watson and McCabe, “The Cob Building Technique. Past, Present and Future,” 63.

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Nonetheless, such projects are not widespread and regions of traditional cob and earth architecture have turned to modern materials such as brick and concrete, on account of the huge labour and time cost of earth construction, with cob buildings often taking whole seasons, if not years to complete.55 However, on larger projects, mechanical machinery may be used to mix the cob such as a tractor or a mortar mixer.

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Figure 26 The labour intensive process of building in cob by hand

55 Kevin McCabe, “About Cob,” Kevin McCabe Cob Building Specialist, accessed 5 December 2021, https://www. buildsomethingbeautiful.co.uk/about-cob.

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On site energy

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The use of earth in 3D printing, requiring both a mixer and a print machine, is energy intensive in comparison to traditional methods, which can be carried out without any electricity or machinery. WASP claim that in the construction of their Gaia house, the electricity required to build the walls totalled 290 kWh. To put this into perspective, the construction of a family home in the UK may require around 90,000 kWh.56 With this in mind, the energy required to run the printer seems almost negligible.

When considering the energy used in printing, it’s worth noting that earth printing has been found to be a more energy intensive process than 3D printing of concrete. Research by the ‘Computing Craft’ group, based at Cardiff University, showed that using the same robotic arm for extrusion (see fig.26), 6.8 kWh was required to print 30kg of cob, while just 3.8 kWh of energy was required to print the same amount of concrete.57 However, the same study also concludes that 3D printed cob still has a lower environmental impact than 3D printed concrete due to the presence of cement and fly ash in the concrete. In the study, the use of electricity to operate the robotic printing arm and extruder contributed to 83% of the overall environmental impact.58 However, using renewable sources to generate the electricity for the printing operation would significantly reduce the impact of 3D printed cob. Furthermore, 3D printing can generate complex shapes (see chapter two) to meet the demands of contemporary building styles and is significantly faster than conventional cob construction due to its automated nature.

56 David Ireland, “The Green House Effect,” The Guardian, 4 May 2005, https://www.theguardian.com/society/2005/may/05/housingpolicy.environment.

57 Alhumayani et al., “Environmental Assessment of Large-Scale 3D Printing in Construction: a comparative study between cob and concrete,” 3-4.

58 Alhumayani et al., “Environmental Assessment of Large-Scale 3D Printing in Construction: a comparative study between cob and concrete,” 6-12.

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Figure 27 Early stage development of printing mechanisms by the Computing Craft research group, led by Cardiff University

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Where does our energy come from?

Digital Earth - Joseph Simms

When thinking about energy usage, it’s important to consider the source of the energy, whether it be from renewable electricity or the burning of fossil fuels. While some equipment can be powered just by electricity, other pieces of machinery, such as large excavators commonly require petrol or diesel to run. However, recent advancements have seen electric excavators begin to come onto the market.59 The burning of fossil fuels causes greenhouse gases such as carbon dioxide, methane and nitrous oxide to be released, causing solar radiation to become trapped in the atmosphere and in turn raising global temperatures. Therefore, to secure a better future for our planet, any equipment used in construction should use electrical, rather than fossil fuel power.

Although a large amount of the world’s electricity is currently produced as a result of burning fossil fuels such as coal and gas, renewable electricity production is becoming increasingly widespread, using solar, wind and other renewable sources to produce electricity (see fig.28). For example, in 2010, the UK produced just 7% of its electricity using renewable sources; in 2021 that figure has risen to 37%.60 Such trends are further underpinned by global climate agreements such as the Paris agreement, which encourage (though don’t legally bind) countries to shift their electrical production to renewable sources.

In the coming decades it may not be unrealistic to presume that in some countries 100% of electricity will be produced without the use of fossil fuels. Iceland already produces 100% of its electricity using renewable sources61 and the UK is targeting

59 Anthony Capkun, “Aecon Pilots Fully Electric Volvo Compact Excavator,” Electrical Business, 10 November 2021, https://www. ebmag.com/aecon-pilots-fully-electric-volvo-compact-excavator/.

60 Department for Business, Energy & Industrial Strategy, “Energy Trends” (UK Government, 30 September 2021), 12. https://assets. publishing.service.gov.uk/government/uploads/system/uploads/ attachment_data/file/1022019/Energy_Trends_September_2021.pdf.

61 Halla Hrund Logadóttir, “Iceland’s Sustainable Energy Story: A Model for the World?,” United Nations, accessed 6 December 2021, https://www.un.org/en/chronicle/article/icelands-sustainable-energy-story-model-world.

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100% renewable electrical production by 2035.62 Remembering that 3DPC technology is still in a relatively infant stage, electrical power seems an appropriate power source for the future of the technology, in line with a global shift away from reliance on fossil fuels and towards renewable electricity.

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Figure 28 Hornsea One wind farm in the North Sea, the largest offshore wind farm in the world

62 Roger Harrabin, “All UK’s Electricity Will Come from Clean Sources by 2035, Says PM,” BBC News, 4 November 2021, sec. UK Politics, https://www.bbc.com/news/uk-politics-58792261.

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Can we 3D print off-grid?

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While WASP claim that their technology has the potential to “become the basis for brand new autonomous eco-cities that are off the current grid”, this claim seems highly impractical at current, given the power usage of the machines. The TECLA project required an average 6kW power to operate.63 Most individual solar panels available today don’t operate at higher than 400 Watts, it would therefore likely take at least 15 panels to operate the printer off-grid, assuming that there’s even sufficient sunlight.

So, while it would potentially be possible to establish such off-grid construction, with the current technology it would certainly be a huge logistical challenge.

There’s another catch in the use of solar panels. Although they can generate electricity by harnessing natural resources and without the need for fossil fuels, the impact of the material extraction and lifespan of the panel must also be considered when quantifying environmental impact. At current, the system for recycling solar panels is completely inadequate, if not almost non-existent. The International Renewable Energy Agency estimates that by 2050 there may be more than 78 million tonnes of photovoltaic panels in landfill. Research by Harvard University suggests that the true number will be much higher.64 One other option for off-grid electricity may be the use of battery cells. In recent years the storage capacity of batteries has rapidly improved, thanks to developments as a result of the emerging electric car market. However, while electric are cars are proposed as a sustainable alternative to fossil fuel vehicles, they still create significant adverse environmental impacts. The batteries used in cars (as well as most new battery powered tools and machines), are made from lithium, a finite resource that must be extracted from nature (see fig.29).65 Lithium can either be mined in the form of ore or clay before being separated through a complex process, or it can be distilled 63 WASP, “TECLA.” 64 Atalay Atasu, Serasu Duran, and Luke Van Wassenhove, “The Dark Side of Solar Power,” Harvard Business Review, 18 July 2021, https://hbr.org/2021/06/the-dark-side-of-solar-power.

65 Thea Riofrancos, “What Green Costs,” Logic, 7 December 2019, https://logicmag.io/nature/what-green-costs/.

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from underground reserves of lithium-rich brine. Either way, the process is energy intensive and can directly ruin large swathes of the natural environment. Furthermore, the extraction of water from the landscape, in the form of brine, can have disastrous consequences for local ecosystems.66 Around half of the world’s lithium comes from the Andean plateau, encompassing parts of Argentina, Bolivia and Chile, known as the “lithium triangle.”

Indigenous communities in this region are already being affected by the negative impact of lithium extraction. The extraction has caused abnormally arid conditions, affecting the flow of rivers and threatening access to clean water for crops and drinking.

These changes also affect wildlife and vegetation, with scientist’s reporting reduced numbers of Andean flamingos.67

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Although ‘green’ technologies such as batteries and solar panels promote positive environmental change, it’s vitally important to consider the raw material cost of everything we use and the impact our use may have on the ecology surrounding the extraction site.

This is not just the case for lithium; the same principle applies to any material that we extract from nature, whether it be metal, wood, water or oil. In order to create a more sustainable future for our planet we must carefully consider the impact of material extraction and try to move towards a system of low or nonextractive architecture.68

Figure 29 Satellite image of lithium mines in Chile

66 Riofrancos, “What Green Costs.”

67 Riofrancos, “What Green Costs.”

68 Space Caviar, Non-Extractive Architecture: On Designing Without Depletion (London: Sternberg Press, 2021).

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Earth as an insulator: comparative analysis

Digital Earth - Joseph Simms

Anecdotal evidence attests to traditional cob constructions as being well thermally insulated due to the dense thermal mass of the walls. However, it’s important to consider that traditional cob construction involves building walls as thick as 800-900mm, far thicker than brick cavity walls.

Cob walls can also be difficult to generalise as each project tends to use slightly different soil and different mix ratios and densities, which in effect change the thermal properties. Despite these challenges, recent EU funded efforts have been made to comprehensively test the performance and viability of cob. The Cobbauge project aims to understand and develop the best cob mixes for use primarily in Britain and France in an attempt to repopularise cob as an affordable and sustainable building material.

In one study control tests were carried out using L300×W300×H200mm blocks of cob with varying mixes.

Comparing U-values, the lowest value obtained was 0.109 W/ m²K with a composition of 50% hemp shiv as the organic fibre.69 While an impressive figure, compared to brick or concrete, the researchers also point out that 50% fibre composition is unusually high and may compromise structural performance. In comparison, tests by WASP reveal that their GAIA house achieved a value of 0.220 W/m²K .70 While obviously worse than the hemp mix tested by Cobbauge, we must remember that they both have fairly different mix ratios and the WASP wall is infilled with rice husk, rather than being a pure earth and fibre block.

The mix tested by the Cobbauge project was also specifically designed as a ‘thermal mix’ with high fibre content. However, they also designed several ‘structural mixes’, which all had U-values higher than 0.271 W/m²K.71 Potentially this is more comparable to the WASP numbers, however, again it’s difficult to draw a direct comparison as they both have a number of variables.

69 CobBauge, “T1, Technical Report: Soil and Fibre Characterisation, Mixes Choice and Mixes Characteristics,” accessed 20 November 2021, 14, http://www.cobbauge.eu/wp-content/ uploads/2019/05/Technical-report_ESITC_feb2019.pdf.

70 Chiliusoli, “The First 3D Printed House with Earth | Gaia.”

71 Cobbauge, “T1: Technical Report,” 11.

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Bearing in mind the difficulty of comparing conventional cob to 3D printed cob, it may be more helpful to compare this U-value to a more common wall build up. A 2014 UK government survey of 109 insulated cavity brick walls, found their average U-value to be 0.63 W/m²K.72 While this is certainly much higher (and therefore worse) than the value of WASP 3D printed earth wall.

Overall, although 3D printing is inevitably more energy intensive than traditional cob construction, it’s far quicker and less labour intensive, a factor that seems vital given the current housing shortage and increasing global population. If powered by renewable electricity, much of the environmental impact of 3DP cob will be eliminated, however, at this stage, we must still be wary of an over-reliance on photovoltaic panels. The U-values that WASP claimed that they achieved certainly show promise and attest to the thermal performance of 3D printed cob. While they are not quite at the highest standard yet, they may still outperform widely used methods such as brick cavity wall. It’s also worth remembering that the structures built by WASP are the first 3D printed earth buildings in the world and it’s therefore likely that the technology will improve in the coming years.

Digital Earth - Joseph Simms

However, despite current assumptions pointing to 3D printed earth outperforming cavity insulation walls, such a wall build up shouldn’t be taken as an acceptable baseline. Instead, 3D printed walls must be compared to high performance sustainable solutions The Passivhaus Trust recommended aspiring to a U-value of between 0.10 W/m²K to 0.15 W/m²K for external walls.73 In order to truly label a building ‘sustainable’ at least in the area of thermal performance, these are the kind of values we need to aspire to.

72 Jack Hulme and Sean Doran, “BRE REPORT: In-Situ Measurements of Wall U-Values in English Housing” (UK Government, Department of Energy and Climate Change, 4 July 2014). 13.

73 Jonothan Hines et al., “How to Build a Passivhaus: Rules of Thumb” (Passivhaus Trust, April 2015), 14.

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4

Structure, Scale & Durability

Digital Earth - Joseph Simms

The structure of earth Due to the layered process of construction, 3D printing of earth does not lend itself to every form. Instead it is best suited to compressive structures such as arches, domes and walls, similar to the forms that may be achieved using conventional masonry construction. Traditional cob houses may also take these same forms. An example being the pointed dome structures of Musgum mud huts in North Cameroon (see fig. 28).74 Studies by Perot et al. have demonstrated that 3D printed cob has compressive strength comparable to that of normal cob.75 Furthermore, the same mechanical strength properties may be achieved with less materials used due to the precise digital structure and geometric structural variation.76 3D printing of earth may allow us to prefabricate elements before assembling them on site. This has two distinct advantages;.

Firstly, it allows the printing process to take place in a controlled environment; as demonstrated in chapter two, 3D printing of clay or earth can already be a challenging and technical process, it is therefore easiest to achieve high quality prints when air temperature and humidity are controlled and constant. Secondly, one major advantage of prefabricated elements is that it is easier to build on small sites where there’s not much room for a large scale printer. Pieces can be manufactured nearby before being transported to site and assembled, which could be particularly useful in tight urban sites. The prefabrication of printed earth remains relatively untested and unpublished, however, one video from IAAC’s ‘Digital Adobe’ research unit shows 99 bricks 74 Fosco Lucarelli, “Musgum Mud Huts,” SOCKS Studio, 26 June 2015, https://socks-studio.com/2015/06/26/musgum-mud-huts/.

75 Arnaud Perrot, Damien Rangeard, and Eric Courteille, “3D Printing of Earth-Based Materials: Processing Aspects,” Construction and Building Materials 172 (30 May 2018): 675 .

76 Alhumayani et al., “Environmental Assessment of Large-Scale 3D Printing in Construction: a comparative study between cob and concrete,” 5.

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elements being printed before being assembled in a 1:1 structure (see fig.29).77

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Figure 30 Vernacular cob domes in Cameroon

Figure 31 3D printed earth wall by IaaC, built from 99 pre-fabricated elements

77 “Digital Adobe,” Institute for advanced architecture of Catalonia, accessed 1 December 2021, https://iaac.net/project/digital-adobe/.

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Cob, compared to concrete or rammed earth, is typically much weaker in compression due to a lack of binding agent such as cement.78 Generally, traditional cob construction doesn’t use any binding agents and relies on straw or fibre binders to provide structural strength. However, WASP claimed that their printing mix for Gaia house contained 10% hydraulic lime.79 The use of a binder such as lime will certainly help to aid the structural integrity of 3D printed earth, however, its use also undercuts the key principle of using exclusively local and sustainable materials. However, hydraulic lime is considered to be more environmentally friendly than Portland cement due to the required temperature of the kiln being lower. Additionally, although the firing process produces GHG due to the high temperatures that must be achieved, hydraulic lime re-absorbs C02 during its lifecycle, unlike cement.80 Lime also dries slower than cement, allowing it to accommodate for some structural movement without cracking, making it ideal for use with earth, which is prone to small amounts of shrinkage as it dries. Unlike cement, lime allows moisture to pass through, making it well suited with earth and clay.81 Despite lime being more compatible with earth and having a lower environmental impact than concrete, the impact of raw material extraction and transport must still be considered.

Hydraulic lime is obtained from limestone, which must be mined or quarried before being processed and transported. With these processes comes inherent environmental damages. Firstly, there is the obvious loss of landscape and habitat caused as a result of large open pits, which are created by blasting or drilling, releasing dust and particulate matter into the air. This negatively impacts

78 Gomaa et al., “Feasibility of 3DP Cob Walls under Compression Loads in Low-Rise Construction,” 2.

79 Chiliusoli, “The First 3D Printed House with Earth | Gaia.”

80 Douglas Kent, “Lime Is a Much Greener Option than Cement,” The Guardian, 23 October 2007, https://www.theguardian.com/commentisfree/2007/oct/23/comment.comment.

81 Kent, “Lime Is a Much Greener Option than Cement.”

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local air quality (see fig.30).82 Limestone extraction may also negatively affect local groundwater supplies by creating sinkholes in the rock, leading to pollutants entering the water supply.83 Although limestone may be found all around the world, there will also inevitably be some emissions associated with transport to processing facilities and eventually to site, undermining the principle of earth 3D printing being able to use readily available local resources.

82 Harsh Ganapathi and Mayuri Phukan, “Environmental Hazards of Limestone Mining and Adaptive Practices for Environment Management Plan’, in Environmental Processes and Management: Tools and Practices, ed. Raj Mohan Singh, Prabhakar Shukla, and Prachi Singh (Cham: Springer International Publishing, 2020): 126.

83 Ganapathi and Phukan, “Environmental Hazards of Limestone Mining and Adaptive Practices for Environmental Management Plan,” 127-129.

84 Cassandra Dove, Fiona Bradley, and Siddharth Patwardhan, “Seaweed Biopolymers as Additives for Unfired Clay Bricks,” 2016, 5.

85 Dove et al., “Seaweed Biopolymers as Additives for Unfired Clay Bricks,”, 17.

86 Dove et al., “Seaweed Biopolymers as Additives for Unfired Clay Bricks,”, 18.

87 Jean-Claude Morel, Abalo Pkla, and Peter Walker, “Compressive Strength Testing of Compressed Earth Blocks,” Construction and Building Materials 21, no. 2 (1 February 2007): 303.

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Alginate is a naturally occurring biopolymer which comes from the cell walls of brown macroalgae seaweed (see fig.31).84 Alginate is therefore a sustainable and renewable resource. Tests carried out by Dove et al. demonstrate that the addition of alginate to a soil mix can improve compressive strength by up to 160%.85 However, they also note that the biggest factor in determining the mechanical strength of mud bricks is the quality of the base soil, though the poorest soils, with a lower clay content, benefit most from the addition of alginate.86 Given the rich heritage of building with un-stabilised earth and cob, and also the longstanding nature of such buildings, it may not be necessary to always use additional stabilisers.87

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In a personal interview, Mohamed Gomaa, part of the ‘Computing Craft’88 research team, claimed that the use of additional stabilisers should not be necessary if the correct proportions of clay and sand are present in a soil. Gomaa explained that an ideal ratio of 20% clay and 80% sand and aggregates should provide optimal mechanical strength. Soils can be tested using a ‘jar test’ to obtain the approximate ratios of clay, sand and silt present in the soil. Mixes may then have to be adjusted with the addition of either clay or sand.89 However, the work of Dove et al. may suggest that alginate could be used to compensate for poorer soil quality, without the need for the optimum mix ratio suggested by Gomaa.90 Perot et al. have also carried out tests of 3D printed cob, finding that the addition of alginate induced a thickening of the mix and a rapid development of the materials strength, allowing successive layers to be applied faster and increasing construction times.91 It’s also worth considering that the use of stabiliser, whether it be cement, lime or alginate, makes the materials far more difficult to reuse or recycle, effectively deeming the material a sort of “brown concrete.”92

88 “Computing Craft: Manufacturing Cob Structures Using Robotically Controlled 3D Printing,” Connected Everything, accessed 8 December 2021, https://connectedeverything.ac.uk/feasibility-studies/ computing-craft/.

89 Mohamed Gomaa, interview with author via Zoom, 7 December 2021.

90 Dove et al., “Seaweed Biopolymers as Additives for Unfired Clay Bricks,”, 17.

91 Perrot, Rangeard, and Courteille, “3D Printing of Earth-Based Materials,” 673-674.

92 Hamard et al., “Cob, a Vernacular Earth Construction Process in the Context of Modern Sustainable Building,” 108.

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Figure 32 Blasting in limestone extraction

Figure 33 Could seaweed provide a natural renewable binder?

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Can we scale up?

Digital Earth - Joseph Simms

Although the structures built by WASP successfully demonstrate that it is possible to construct buildings using 3D printed earth, it is worth remembering that both Gaia and Tecla are small scale, single storey dwellings. For this technology to have a practical and viable future as a sustainable construction method, it’s essential that earth 3D printing can operate at a larger scale, to accommodate a broader range of uses.

Most 3D printed buildings which have been constructed, (in any material) have been small single storey dwellings. However, there are a limited number of projects, which have used the method at a larger scale. In Dubai, 3D print construction company Apis Cor built the world’s largest 3D printed building, standing at 9.5 metres tall across two stories and 640 m² of floor area.93 Despite the building utilising 3D printed concrete walls, the floor was instead constructed of conventional pre-cast concrete slabs.94 Due to the 3D printing method only being structurally stable in compression, it is not possible to 3D print the whole building without additional materials being used to span floors. A more sustainable approach may be to use timber or cross laminated timber (CLT) floor slabs, which require less energy than concrete slabs to produce, and may also be reused or recycled at the end of the building’s life cycle.95 In supporting floor slabs, it is important to remember that cob generally has a much weaker compressive strength than concrete, which has traditionally been compensated by wall thickness.96 However, due to computer designed, hollow geometric properties of 3D printed earth, the same load-bearing function may be achieved with conventional 93 Alhumayani et al., “Environmental Assessment of Large-Scale 3D Printing in Construction: a comparative study between cob and concrete,” 2.

94 India Block, “World’s largest 3D printed building completes in Dubai,” Dezeen, December 22, 2019, https://www.dezeen. com/2020/12/22/kamp-c-completes-two-storey-house-3d-printedone-piece-onsite/.

95 Ying Liu, Haibo Guo, Chen Sun and Wen-Shao, Chen, “Assessing Cross Laminated Timber (CLT) as an Alternative Material for Mid-Rise Residential Buildings in Cold Regions in China—A Life-Cycle Assessment Approach,” Sustainability 8, no.10 (2016): 11.

96 Gomaa et al., “Feasibility of 3DP Cob Walls under Compression Loads in Low-Rise Construction,” 2-3.

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cob construction, with less material usage.97 Although earth, given its vernacular heritage, is not associated with large scale construction in the same way that concrete and steel are, the material does have some legacy of multi storey buildings. The city of Shibam, Yemen, is distinctively characterised by its adobe towers. These rise as high as 30m, earning Shibam the nickname, “the Manhattan of the desert” (see figs.34-35).98

Digital Earth - Joseph Simms

The towers of Shibam are built on stone foundations with walls supported by timber pillars, the ceilings being constructed of split date palm trunks.99 The tops of the towers, or in some cases the whole building, are protected from rain by white lime plaster.100 While the thick, adobe brick walls of Shibam do not bear exact resemblance to a 3D printed earth mix, the ancient towers suggest that it’s possible to use earth to build multi storey buildings, supported by a timber structure. The use of 3D printing and CLT floor slabs and pillars could prove a viable option for a more contemporary form of earth construction, which is faster and more accurate than the buildings of Shibam. However, it is impossible to decisively conclude if 3D printing of earth is suitable for multi-storey buildings without first carrying out more tests. Notably, the most significant factor determining the mechanical and structural properties of 3D printed earth is the soil composition and mix ratios, which will be discussed further in the final chapter.101

97 Gomaa et al., “Feasibility of 3DP Cob Walls under Compression Loads in Low-Rise Construction,” 15.

98 Gulnaz Khan, “This Ancient Mud Skyscraper City Is the “Manhattan of the Desert”,”National Geographic, 4 March 2017, https:// www.nationalgeographic.com/travel/article/shibam-mud-skyscraper-yemen 99 Ronald Lewcock, Wādī Hadramawt and the Walled City of Shibām (Paris, France: Unesco, 1986), 65-74.

100 Lewcock, Wādī Hadramawt and the Walled City of Shibām, 74.

101 Gomaa et al., “Feasibility of 3DP Cob Walls under Compression Loads in Low-Rise Construction,” 3.

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Figure 34 The earth skyscrapers of Shibam, Yemen

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Figure 35 Section of the house of ‘Alwi bin Sumayt in western Shibam. Note the earth walls becoming progressively thinner on each level

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How durable is earth?

Digital Earth - Joseph Simms

Durability is arguably one of the least explored areas of 3D printed earth, due in part to the emerging and recent nature of the technology. Because of this, it’s impossible to draw firm conclusions, however some assumptions on the durability of 3D printed earth may be made by exploring traditional cob architecture. One key aspect to understand is that cob is inherently not as durable as concrete and requires some maintenance.102 Ultimately, in the fast-paced world we now live in, the need for regular maintenance could prove a huge barrier to the appeal of living in 3D printed earth houses. However, the long-standing examples of vernacular earth architecture attest to earth durability, if properly maintained. An example being the towers of Shibam, some of which have stood for over 300 years.103 Whether earth buildings can be left exposed is largely down to local climate conditions. In arid regions of the world, earth buildings are usually left untreated or finished in an additional layer of clay and earth render. Leaving the façade as raw earth means that it can be easily and quickly patched up, if needed.

In some places it is traditional to re-plaster buildings with earth every spring.104 In cold and rainy climates additional protections need to be put in place to protect a cob wall. Rain is the main factor which may easily damage earth structures; however, this can be easily prevented by using overhanging roofs to stop rain coming in direct contact with the structure. Alternatively, durability can be improved by the addition of lime plaster on the exterior façades, as is commonplace in many cob buildings in the UK (see fig.33).

Cob buildings must also be carefully treated when it comes to finishing as they must be able to ‘breathe’, allowing moisture and humidity to pass through.105

102 Mohamed Gomma,, interview with author via Zoom, 7 December 2021.

103 Salmá Samar Damlūjī, The Valley of Mud Brick Architecture: Shibām, Tarīm & Wādī Hadramūt : Ancient to Contemporary Design (Reading, UK: Garnet Pub, 1992), 88.

104 Adam Weismann and Katy Bryce, Building with Cob: A Step-byStep Guide (Totnes, England: Green Books, 2006), 150-151.

105 Weismann and Bryce, Building with Cob, 135-137.

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Figure 36 Cob house in Devon UK, utilizing both exterior lime render and an overhanging roof to protect it from rain and degradation

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5

Concluding remarks: where & who?

Digital Earth - Joseph Simms

Where can we build with earth?

Soil composition varies with climate and geography, however, it is generally a mix of sand, clay, silt and occasionally larger aggregates, with the ratios of each varying depending on location.

Therefore, in order to build with earth, one must understand the exact ratios of the soil, as well as being able to adjust ratios of straw and water accordingly.106 The ideal mix of around 20% clay suggested by Mohamed Gomaa appears to be a good benchmark to aim for when 3D printing earth, however Gomaa also mentioned that “there is no recipe for cob”.107 Instead, mixing recipes have relied on traditional knowledge of local soil types. Due to the technical nature of 3D printing with cob, it is not sufficient to rely on word-of-mouth local knowledge, however it may be possible to formalise mix ratios based on local soil types. Building codes are also currently a major barrier to the development of 3D printed and cob architecture, with very little codified information about cob construction, with cob building currently not featuring in UK Building Regulations.108 Formal earth building codes could help to develop guides for ideal soil mixes to 3D print in different localities around the globe, to suit different climates and geographies.

Although it is possible to get planning permission for cob houses in the UK, the lack of codified or standardised information means that traditional knowledge must be relied on. Standard earth construction already requires careful consideration of soil ratios; the extra factors introduced by the use of a 3D printer only complicate this massively. The mix must be fluid enough to be able to be printed as a liquid, though a highly viscous one. At the same time, it must also be solid enough to be able to retain enough structural integrity to support successive layers being 106 Minke, Building with Earth, 11-12.

107 Mohamed Gomaa, interview with author via Zoom, 7 December 2021.

108 Wassim Jabi, interview with author via Zoom, 7 December 2021.

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printed on top. Furthermore, once this balance is reached, the mix must be prevented from drying out or it may clog the extruder and fail to form a smooth path.

Clay soils can be found all around the world, however, with varying concentrations and qualities.111 With this in mind, as is the case with traditional earthen architecture, 3D printed earth mixes would have to be carefully adapted to consider local climates and geographies, taking into account the knowledge of vernacular earth architecture in the region. It’s unlikely that 3D printing of earth will be able to be universally codified and instead would have to be adjusted to suit local soils and climates. This complication could prove a barrier to the widespread use of the technology, however, it may also encourage and support the use of local materials and related skills.

Digital Earth - Joseph Simms

While it’s logistically impossible in this paper to test, analyse and comment on different soil samples from all around the world, earth buildings can be found on every continent, (apart from Antartica) across more than forty countries. This attests to the global suitability of earth as a construction material.109 Through a formal literature review, Hamard et al found evidence of cob construction in twenty-seven countries, and it is likely that more countries feature cob or cob-like constructions that are not published in academic literature (see figs.34-36).110 Given the widespread use of earth and cob architecture in various regions of the globe, 3D printing of earth is likely appropriate to be applied in a variety of climates and locations, with local or semi local access to appropriate soil.

109 Alejandro Veliz Reyes et al., “Negotiated Matter: A Robotic Exploration of Craft-Driven Innovation,” Architectural Science Review 62, no. 5 (3 September 2019): 406.

110 Hamard et al., “Cob, a Vernacular Earth Construction Process in the Context of Modern Sustainable Building,” 105.

111 Ronald Rael and Virginia San Fratello, Printing Architecture: Innovative Recipes for 3D Printing (New York: Princeton Architectural Press, 2018), 140.

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Figure 37 School building in Thailand by Chiangmai Life Architects, constructed of adobe

Figure 38 Al-Aan Palace built from cob, in Najran, Saudi Arabia

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Figure 39 Earthen School in Pakistan, by ZRS Architecture

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Automation and labour

Digital Earth - Joseph Simms

A final aspect that must be discussed is the process of automation and its impacts. Construction is a labour-intensive process and a major source of global employment. Before embracing a new paradigm of automated, mass customised construction, its impacts must first be assessed. To frame this discussion, it is important to understand that the construction industry is historically and currently lacking in the implementation of automated processes, in comparison to other industries.112 While advancements in electronic and hydraulic machinery have allowed some advancements in construction speeds, more than 90% of global infrastructure projects are either late or over budget, according to Bent Flyvbjerg of Oxford University.113 3D printed construction may allow for increases in building efficiency, as we have seen with projects such as WinSun’s ten homes in 24 hours.114 While WASP’s buildings have taken a little longer, with TECLA taking 200 hours to print, this is still a fraction of the time that it would require to build a similar size dwelling using traditional cob methods, and only required two people on site to supervise the machine. Ultimately, this faster speed and smaller workforce should help to reduce the price of building with earth and make the material more accessible. It is also likely that in the future, the overall cost of the process may decrease due to falling costs of machinery, as discussed in chapter two. For 3D printed earth buildings to offer a viable, sustainable method, they must be accessible, and affordable. However, without further structural testing and case studies of larger 3D printed earth buildings, as well as expansive codified methodologies of building with local soils, it’s too early at this point to definitively conclude whether 3D printing of earth will become a widespread and popular method of construction.

Just as the mass production and mechanisation of the first industrial revolution catalysed our present climate crisis, we must ensure that any further paradigm shifts towards a world 112 “Efficiency Eludes the Construction Industry,” The Economist, 17 August 2017, https://www.economist.com/business/2017/08/17/ efficiency-eludes-the-construction-industry.

113 “Efficiency Eludes the Construction Industry,” 114 Holt et al., “Chapter 17 Construction 3D Printing,” 353.

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Finally, it must be considered how automation impacts the labour force itself. In reference to the role of the designer, Cardoso Llach argues in favour of automation and computer systems as a way to “free the people from the toils of dealing with materials, liberating them as creative agents.” Furthermore, automated processes eliminate the role of the master builder in favour of a single designing mind, where ideas are translated from idea to digital to physical.116 In this regard, automated construction is not just a streamlining of construction but also of design.

Digital Earth - Joseph Simms

of automation don’t further damage our planet. As discussed in chapter three, any use of machinery, including 3D printing uses energy and is therefore inherently less sustainable than relying purely on human labour. However, a pre-industrial model of construction may also come at the expense of often poorly-paid and overworked labourers. The time involved in building a cob house in the present day makes the method just as expensive, if not more expensive than more common modes of construction such as concrete, steel and brick. In 2020, Iranian practice ZAV Architects beautifully demonstrated the potential of mud architecture, constructing what they call a “cultural residence”, of colourful interconnected mud domes (see figs. 40-41).115 However, labour accounted for 65% of the construction costs due to the slow progress of building with earth. The use of 3D printers may allow similar projects to be built at a far lower cost due to reduced time and labour, making such houses more financially accessible.

However, beyond the designer, automation may have a less positive impact. Economists at MIT found that increased use of automated robotics in industry had a negative effect on both wages and jobs.117 While it’s inevitable that 3D-printed construction would reduce demand for on-site labour, unlike some industrial automated processes, construction 3D printers are not fully autonomous and do require some assistance on site for the mixing and loading of materials as well as quality 115 “PRESENCE IN HORMUZ 02| MAJARA RESIDENCE,” ZAV Architects, accessed 9 December 2021, http://zavarchitects.com/.

116 Cardoso Llach, Builders of the Vision, 46.

117 Sarah Brown, “A New Study Measures the Actual Impact of Robots on Jobs. It’s Significant,” MIT Sloan, 29 July 2020, https://mitsloan.mit.edu/ideas-made-to-matter/a-new-study-measures-actualimpact-robots-jobs-its-significant.

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control. Semi-mechanised and industrial processes such as the pouring of concrete have existed in construction for years. 3D printing would do little to de-skill an industry that has so widely embraced concrete for the last century. Moreover, 3D printing of earth may even encourage greater regional and specialised building skills and practises, moving away from the monotonous mass production of concrete structures, and instead towards a more sensitive and customised use of localised resources. The current model of resource and labour intensive construction must be replaced by a technologically intensive model, freeing labourers from back-breaking work in poor conditions. Instead, an emphasis must be placed on new digital skills and intimate knowledge of local resources.

Figure 40 Cultural retreat in Iran constructed out of earth, by ZAV Architects

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Figure 41 Interior of earth house by ZAV Architects

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Final Conclusions

Digital Earth - Joseph Simms

It is clear that current building practises such as the use of concrete are failing the planet.118 Since the dawn of the first industrial revolution, mass production and damaging natural extraction have been the dominant modes of manufacturing. To reduce and overturn the damage caused by these industrial processes, we may look to traditional and pre-industrial methods of production, while also embracing contemporary technologies. The use of earth, a traditional and widely-used building material, coupled with 3D printing, a state-of-the-art method of manufacturing, offers a promising integration of craft and local materials, with cutting-edge digital manufacturing and design.

The technology is still in its infancy, however, early case studies by WASP attest to the method being a viable mode of construction.

In order to develop the technology further, it is essential to reduce the energy use required for printing and also ensure electrical power is obtained through sustainable and non-polluting sources.

In this regard, 3D printing of earth is only intrinsically sustainable if these key conditions are met. Thermal performance is also vital to sustainable building practice. 3D printing of earth performs well due to the digital geometries of the wall section, allowing for a separation of structural and thermal materials. However, thermal performance still needs to be improved, which could be made possible by further optimisation of internal wall geometries or additional insulation.

Research by the “Computing Craft” group has demonstrated that 3D printed earth has compressive qualities comparable to conventional cob. However, less material is required as a result of digital structural optimisation. Timber may be appropriate as an additional structural material, for both columns and floor slabs, due to its low carbon footprint and reusable qualities.

Longstanding examples of earth architecture attest to earth’s qualities of durability. However, in certain climates additional protection may be required, such as a lime plaster coating or an overhanging roof. Vitruvius’ theory of firmitas may favour the solid durability of concrete and brick. Nonetheless, the nuanced repair 118 United Nations Environment and IEA, “Towards a Zero-Emission, Efficient, and Resilient Buildings and Construction Sector: Global Status Report 2017,” 6.

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and careful care of earth buildings may offer equally long lasting qualities, while also providing an opportunity for specialised labour skills.

3D printing of earth can be highly technical in finding the perfect mix ratios that balance rheology and structural properties. Given the wealth of traditional earth architecture globally, it is essential to embrace, understand and codify local earth building practises, in order to aid the development and understanding of soil mixes for earth 3D printing. This will most likely have to be carried out on a highly localised basis; however, such practises would ensure that material chains are local and low impact practises.

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Overall, the 3D printing of earth is still in the early stages of development. However, in line with growing interest in digital fabrication and sustainable building methods, the technology is likely to receive increasing attention in the coming years. Rather than being used as an exclusive mode of construction, the method may also find uses as component within a larger framework of considerate localised craft and sustainable material sourcing.

Digital earth may catalyse a turn away from outdated models of mass industrialisation, in favour of technologically proficient, yet sensitive local practices.

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