Soiled Again
In the world of architectural design competitions, there are a few chestnuts that come up time and again. Green roofs are probably my favorite, as they seem to make up for a lot of sins or, in reality, they sort of paper over the technical corners you have to cut to produce a credible design concept in very little time and usually with no budget. But my own chestnut that I throw on the table almost every time is literally the oldest construction trick in the book: rammed earth.
On its face, rammed earth seems to make a lot of sense. It is as hyper-local a material you can get, which means there is little transportation energy expended to get it to site. And, in theory, you do not need to do much processing to get it into a consistency you can use.
Simply put, rammed earth is a combination of soil, gravel, clay, and concrete or other binding admixtures, layered into a mold, and then mechanically compacted into the form of a wall, floor, column, or nearly any architectural element save a roof or ceiling. To construct a wall, for example, you can vary the earthen layers that you individually tamp down so that the final construction reveals a striation that mimics geological layering. Biophilic design principles suggest such textures, colors, and forms of such a natural architectural system would inherently appeal to humans—reducing stress and providing a restorative benefit for over-taxed minds. We definitely need more of that from architecture.
Rammed earth or other earthen structural systems can also offer benefits for reducing embodied carbon, a critical design imperative in so many cities now. In a 2019 university study by Portuguese civil engineers (sorry, the link is behind a paywall), they demonstrated through a lifecycle assessment approach that rammed earth blocks could deliver at least a 50 percent reduction in environmental impacts—embodied energy and global warming potential—compared to conventional blocks like concrete. That’s significant when we are looking for low-carbon design strategies to meet emerging building codes for embodied carbon, such as the forthcoming changes to CalGreen in California, emerging embodied carbon regulations in Sydney or the current planning requirements for whole life-cycle carbon emissions calculations in London.
I live in the Southwestern United States, a region with a long tradition of earthen structures such as the 1,000-year-old Taos Pueblo , which is the oldest continuously inhabited community in the USA (and a UNESCO World Heritage site). Adobe construction is less rammed than it is packed; applying new straw and earthen layers every year is often a central part of the community experience of living in adobe architecture. In the case of the Taos Pueblo, the thick adobe walls provide an environmental thermal mass benefit, keeping people warm in the high desert’s cold winters and cool during the increasingly scorching summer months.
Thermal mass, which helps temper our daily environment by increasing the ability of exposed surfaces to absorb and hold energy, thereby moderating indoor temperatures (i.e. preventing wild swings between hot daytimes and cold nights), would be more common in architecture if it were not for the increased weight and area often required to provide adequate volumes of what is often just exposed concrete structure. The energy and comfort benefits of increasing concrete volumes for thermal mass rarely competes with the current need to minimize material quantities and reduce embodied carbon. In projects where we value passive cooling and where weight and area are not always the primary concerns, like a single-family house in a rural setting, rammed earth can provide a low-carbon alternative to concrete—thus, I would argue it is something we should continuously put on the table for projects.
Woods Bagot has incorporated rammed earth elements into several projects in Australia, reinforcing a connection to the land itself as only one aspect of the broader connection to Country . Part of the passenger journey at our recently completed Port Hedland International Airport , in Western Australia, features rammed earth walls reflecting the land of the state’s vast Pilbara region and the nearby Karijini National Park , while our Sydney studio has investigated using precast rammed earth panels to form balustrades for new hotel (QIC ) in the northwest part of the city. ?
Of course, it does not always make environmental sense when you try to translate it to denser or more programmatically complex contemporary building typologies. We recently studied the potential for precast rammed earth panels for an envelope for a proposed office building in Abu Dhabi; the effect was certainly striking, but once we got into the technical details we found we would still require a significant amount of concrete and a structural backing system that reduced the rammed earth component to a form of surface decoration. In our case, although we loved the look, that was not a good enough solution to our need to reduce the embodied carbon of the entire building. The envelope had to contribute more to that goal given its significance in the overall embodied carbon footprint. Soiled or foiled, these are the trade-offs you make when you are applying sustainable imperatives to design.
There seems to be a new book every year on earthen architecture, certainly too many to list. But I have a few favorites I will share.
Jean Dethier’s book, The Art of Earth Architecture , from 2020, is the latest comprehensive—perhaps definitive—book exploring earthen architecture as practiced or critically understood by trained architects. With several essays by other contributors, case studies of significant projects, chapters on construction techniques and architectural history, and page after page of beautiful images, this book is well worth the investment. It is also a great starting point for further investigation of specific projects using other sources since it is not a “how-to” but more of a catalog of what has been done. The 2019 book, Essential Rammed Earth Construction , by Tim J. Krahn, advertises itself as a “step-by-step” guide if that is what you are after. Krahn is an engineer, so this tends to be more of a technical book for practitioners rather than an inspiration source.
Stone, Log and Earth Houses , by Magnus Berglund, from 1986, is one of those other types of practical books from a certain era meant to inform the do-it-yourselfer on how to implement unconventional and time-honored building practices into residential construction. This one is typical of the genre, filled with great photos and helpful diagrams (but good luck getting permits for these houses today!).
If you like conventionally dry, if not authoritative histories, check out art historian Vincent Scully’s Pueblo: Mountain, Village, Dance , from 1975 (derived from a 1972 show at the Walker Art Center). This is as much a cultural study as it is about architecture, per se, but I have always appreciated its comprehensive approach to the Southwest United States and its attention to how Native Americans traditionally used their cities and architecture (at least, as viewed through the lens of a Yale University-based art historian!). The comparisons between Taos Pueblo and the Acropolis in Athens are almost laugh-out-loud funny in their passé Euro-centric panic.
Earth architecture aside, way back on March 23, I was in Palm Springs for the opening of the 1931 Aluminaire House, designed by Albert Frey and now permanently installed at the Palm Springs Art Museum. Conceived as an all-aluminum exhibition house for the Architecture and Allied Arts Exposition of 1931 in New York, the house is a sort of quasi-prototype of a circular economy project—designed to be compact, easy to disassemble, and, ultimately, mass-produced—it is now a quite visible display of how early Modernism remains as relevant as ever. You can read my much longer take on the Aluminaire in the May issue of Architectural Record .