On Lightness

10. The Engineering Historian: Giulia Boller

This month, I interviewed architecture and engineering historian Dr. Giulia Boller, who is a lecturer and senior postdoctoral researcher at ETH Zurich. We talked about her PhD and her recently published book [https://verlag.gta.arch.ethz.ch/de/gta:book_926d0f3e-3493-4c55-8f36-930456af72c0] on the shell builder Heinz Isler and reflected on the role of mid-century lightweight pioneers in the reduction of building material. This episode was moderated and produced by Leon Hidalgo. lllightness is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber. The following article is meant as an informational extension of the podcast episode: Giulia was trained both as an architect and civil engineer. In her first years after finishing her studies, she worked at the Renzo Piano Building Workshop, where she first came into contact with an architectural language of lightness. After that, she was accepted as a PhD student at ETH, where the opportunity arose to write a dissertation on the newly acquired archival remains of the shell builder Heinz Isler, who had passed away in 2009. She recently published parts of this research, among others, in a book through gta Verlag titled Heinz Isler, Built Experiments – Entrepreneurial Networks [https://verlag.gta.arch.ethz.ch/de/gta:book_926d0f3e-3493-4c55-8f36-930456af72c0]. The idea of lightness for Giulia is directly linked to the work of the mid–20th century lightweight pioneers. First coming to mind is Frei Otto, but also figures like Robert Le Ricolais and Heinz Isler himself. Lightness¹ the quality of having little weight Resource scarcity and cheap labour in certain mid-century contexts (for example postwar Italy or Mexico) were not abstract economic conditions but concrete forces shaping how people like Pier Luigi Nervi and Félix Candela drew and built. These constraints pushed them toward structural languages that did more with less material. At the same time, Giulia sees this as part of a broader, global cultural shift: architects and engineers became fascinated with long-span, columnless spaces, and for the first time the public gaze began to include not only the architects of these buildings but also the engineers behind them. Within this constellation, the fascination with natural structures becomes clear in Frei Otto’s collaborations with biologists, where an interdisciplinary research process set out to trace connections between form and forces. At the same time, Heinz Isler saw biomatter more as a source of formal inspiration rather than as something he would ever want to reproduce literally. Sergio Musmeci, on the other hand, turned more toward the mathematical foundations of shape, while still sharing with the others a key reference point in D’Arcy Thompson’s book On Growth and Form. One of Giulia’s favourite structures is the Deitingen service station by Heinz Isler, where two mirrored triangular shells form simple roofs over a roadside gas station. Another is the Gatti Wool Factory in Rome by Pier Luigi Nervi, whose roof is conceived as a series of minimal-material slabs. Lastly the concrete factory by Swiss engineer Heinz Hossdorf comes to mind, which for Giulia exemplifies a collaborative effort in which an engineer takes an active role in shaping an architectural masterpiece. lightness² the state of being light in color or shade At RPBW, the aspect of lightness was mentioned as a spatial concept of visibility and transparency. Not in the sense of a material property, but as the ability, upon entering a room, to read the full stratification of spaces and elements that together make up the building. Giulia recalls from a research project on the Olympic Stadium in Munich that new plexiglas panels had to be developed specifically for the roof. They needed to let light pass through while avoiding strong reflections that would disturb television cameras. This was crucial because the Olympic Games (1972) for the first time were to be broadcasted live. For Isler, one of the key challenges of shell construction was how to bring light into the dark centre of these roofs. His answer was to develop a production method for glass-fibre shells that could be used as central skylights. These glass-fibre domes could be produced using similar techniques to his hanging models. Legend has it, that selling this system to another company provided the capital he needed to open his own engineering office. On a recent trip to Algeciras in southern Spain, Giulia visited the city’s market hall, an early concrete-shell structure by Spanish engineer Eduardo Torroja. Its skylight produces a striking and unexpected light atmosphere, leaving a strong impression on her. lightness³ being carefree or feeling without burden When thinking about the physical feeling of lightness, the first image that comes to Giulia’s mind is the famous load tests of Candela’s shells, workers standing on the thin concrete surfaces to prove their structural sufficiency. For her, the sensation of lightness is connected to structures that suggest movement, or that are literally in motion as well as structures that visualize gravitational forces. Towards the end of her work on Isler’s archive, Giulia opened a box that had apparently gone untouched throughout the entire research process. Inside she found something she had not expected at all: computer calculation printouts. Until then, Isler had been known to oppose to the use of computers in structural calculation. The discovery gave Giulia the rare opportunity to reveal a completely unknown side of the Swiss engineer. 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9. The Ultralight Backpacker: Christian Handtke

This month, I interviewed ultralight backpacker and storeowner Christian Handtke from chrispacks [https://www.chrispacks.com/], who has spend most of his lifetime in the outdoors. We talked about his experience hiking the pacific crest trail, ultralight gear and the material it is made of. This episode was moderated and produced by Leon Hidalgo. lllightness is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber. The following article is meant as an informational extension of the podcast episode: Chris hiked the Pacific Crest Trail in 2017 and spent six months living in a tent. The experience showed him how important it is to keep pack weight low. After returning home, he opened a small outdoor shop in southern Germany specializing in ultralight gear. Lightness¹ the quality of having little weight Chris thinks most people take too many things on their hikes. Going lighter and lighter demands risk-taking and lowering your comfort, while at the same time easing movement. Chris doesnt mind. Especially on long hikes reducing weight makes it easier to hike and brings him closer to the beauty of the surrounding landscape. For weight reduction, an easy place to start is a lightweight backpack, with less complexity and just the necessary features. Bringing water on a hike is a must, but when hiking in areas with a lot of running water, bringing a water filter can be an easy way to save weight. Shelters range from single person pyramid tents under 500g, supported by hiking poles, to heavier Mountaineering tents with many poles forming a small geodesic dome. In High Altitude Climbing reducing weight shouldn’t be the main priority. But even there a lot of weight could be saved when buckminster fuller in 1975 designed the oval intention tent for The North Face. It is the structural origin of most of the black and yellow tents we find nowadays at the Mount Everest Base Camp. Reducing the amount of pockets or thinning the material are ways to minimize weight but a thinner material always comes with the risk of damage by abrasion. Fabrics, that have been successful in the compromise of thinness and stability are silnylons on the cheaper end and dyneema for the higher budget tents. For kitchen products Titanium is the go-to material, as it is ultralight and has a good thermal conductivity.The main idea is use less equipment and use it for more opportunities 15 kilos are a maximum for Chris, while he usually goes hiking with much less weight. His lightest setup for day-hikes in his area is around 1,5kilos. Sleeping outside without a tent is also a good option for saving weight but sadly it is illegal in most countries. lightness² the state of being light in color or shade Chris likes to sleep just using the inner mesh of the tent to immerse himself into the rythm of the sunlight but once the sun is really up UV Protection can be an important aspect on long hikes. Instead of relying on endless amounts of sunscreen he prefers to use a sunhoodie made from uv-protective fabric. Mobile PV modules are a good option for people who bring drones and other tech with them, although they’re quite inefficient at charging while hiking. Chris prefers to use his devices as little as possible and to carry a small power bank, which is usually enough for up to six days of phone use. lightness³ being carefree or feeling without burden For him, feeling light - both physically and mentally, is closely connected to the six months he spent hiking the Pacific Crest Trail. Over time, he felt himself becoming one with his surroundings and the rhythms of nature, disconnected from the pressures of everyday city life. The constantly changing landscapes reinforced that feeling, just as he grew used to one environment, the trail would shift into another. After six months on the trail, Chris, like many others, enjoyed returning to his routine and the luxuries of supermarket food, hot baths, and a comfortable bed. But the comfort didn’t last long before he began longing for life on the trail again. Chris has always been fascinated by gear. Long before opening a store, he was sewing backpacks for friends and experimenting with lighter designs. After returning from the trail and missing the hiking life, turning that passion into a business felt like a natural next step. Opening his shop created new opportunities. Testing products became a reason to head back outside, and conversations with customers gradually built a network of ultralight enthusiasts. The broader philosophy behind ultralight backpacking, reducing gear to the absolute essentials, can be traced back to Ray Jardine, an aviation engineer and professional climber. His 2009 book Trail Life has become something of a bible for many ultralight hikers. Chris has read it too, and in many ways his store carries that same energy and philosophy. So if you ever find yourself in Lenggries, south of Munich, and need stellar advice on your gear, stop by chrispacks [https://www.chrispacks.com/], you’ll likely walk out lighter. Get full access to lllightness at lllightness.substack.com/subscribe [https://lllightness.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_4]

8. The Ephemeral Agent: Alessandro Pasero

This month, I interviewed architect and researcher Alessandro Pasero [https://alessandropasero.com/], a PhD candidate at Politecnico di Milano. We talked about his research on performance and the histories of ephemeral architectural production, and reflected on the tension between temporary spatial practices and the enduring weight of our built environment. This episode was moderated and produced by Leon Hidalgo. lllightness is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber. The following article is meant as an informational extension of the podcast episode: Alessandro’s practice moves between architecture, installation and performance. In this dance between disciplines the research and practice necessarily inform each other. When he speaks about lightness, he places it at the edge of architecture as defined by Vitruvius’s firmitas. Lightness¹ the quality of having little weight Alessandro finds himself in the paradox of living a somewhat nomadic life while carrying the massive weight of cityscapes and infrastructures that are nonetheless assigned to him. When he visits a city, he tends to observe its small, temporary spaces of flux, as they reveal the conditions of inhabitants and their ways of life more clearly than monuments do. In his master’s thesis, he explored this idea by designing an ephemeral place of gathering built from scaffolding elements. When thinking about his favorite structures, his mind naturally turns to the early works of Diller & Scofidio, particularly projects such as Slow House [https://dsrny.com/project/slow-house] and Moving Target [https://dsrny.com/project/moving-target]. lightness² the state of being light in color or shade Thinking of light as an ephemeral agent, Alessandro argues that architecture should no longer be concerned primarily with form, but also with the fluxes of matter. While light embodies these fluxes, our built environment doesn’t. In this context, he refers to the work of Andrés Jaque with his Office for Political Innovation [https://officeforpoliticalinnovation.com/], citing the Reggio School [https://officeforpoliticalinnovation.com/work/colegio-reggio-explora/] as an example of architecture that openly acknowledges and makes visible its material, social, and environmental flows. In regard to supposed lightness of fully glazed façades, Alessandro points to the problematic qualities of glass, when it is placed uniformly or without regard for what it reveals. In this way, architecture can produce conditions of surveillance and broadcasting, as Beatriz Colomina [https://soa.princeton.edu/people/beatriz-colomina] has described in her books Privacy and Publicity and Domesticity at War. When thinking about moments defined by special light qualities, Alessandro, having grown up in Rome, inevitably recalls visiting the Pantheon on a Sunday, where the light materialized as a central column coming down from the skylight. He also connects this memory to the flickering beams cutting through darkness while clubbing. Alessandro was reminded of this experience in a light installation at Horst Arts & Music Festival in 2022, where the Belgian architecture practice Traumnovelle [https://traumnovelle.eu/] designed a mesmerizing light installation [https://www.youtube.com/watch?v=LDL9rSrjVok]. lightness³ being carefree or feeling without burden Alessandro feels lightness when he can be in a moment fully immersed while at the same time having no attachments or lingering doubts. While recently building a pavilion [https://linebiennial.com/campato-in-aria] for the Armenian Architecture Biennale, he had the opportunity to visit the country and, in particular, the Geghard Monastery [https://whc.unesco.org/en/list/960/], where a spiritual space carved deep into massive rock unexpectedly evoked in him a strong sense of lightness. video by ©LorenzoBasili The idea of lightness also brought Alessandro back to a quote from a book that was read to him as a child and that he recently revisited: “Take life with lightness, for lightness is not superficiality, but gliding over things from above, not having weights on your heart.”— Italo Calvino, Six Memos for the Next Millennium (Sei proposte per il prossimo millennio) Mirabilia was a project developed for the Architecture Festival in Rome in 2022, where Alessandro understood that, in this very specific local condition, minimal actions such as marking abandonment and accumulated trash could be a more effective architectural response than any imagined built intervention. He reflects that this project marked the first instance of a pattern he began to recognize, one that may become to define his way of working. Get full access to lllightness at lllightness.substack.com/subscribe [https://lllightness.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_4]

7. The Lightweight Engineer: Julian Lienhard

This month I interviewed engineer Julian Lienhard, partner and founder of str.ucture [https://www.str-ucture.com/en] and head of the structural design chair at the University of Kassel [https://www.uni-kassel.de/fb06/en/institutes/architecture/departments/structural-design/home.html]. We talked about his academic biography, working at SL Rasch [https://www.sl-rasch.com/en/], ultralight backpacking, and his experiences at the Expo in Japan. In our conversation it became obvious that Julian found his calling and has this immense amount of energy and motivation for the topic of lightweight architecture. This episode was moderated and produced by Leon Hidalgo. lllightness is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber. The following article is meant as an informational extension of the podcast episode: In 1998, Julian had his first design-build experience in a high school project of building a climbing wall in South Africa. He found a fascination for the matter and decided after finishing high school to go and study architecture or structural engineering. By chance he landed in the engineering studies in Stuttgart and there met Juergen Hennicke in the Lightweight Institute, the last colleague left of the Frei Otto times. The unusual building of the ILEK [https://www.ilek.uni-stuttgart.de/en/] intensified his fascination for architecture and specifically for the lighter kind. Later in his third year of studies, by coincidence he stumbled into a job at Bodo Rasch’s office. There he worked nonstop on the famous Medina Umbrellas [https://www.sl-rasch.com/de/projekte/u-26-piazza/] together with another freelancer, who later became his office founding partner. Lightness¹ the quality of having little weight Being a passionate climber, the niche of ultralight backpacking was a natural fit for Julian. With his climbing partner, discussions arose frequently about the best lightweight equipment. While his partner mostly opts for highly specific tools, Julian prefers multifunctional ones that save weight but have recently begun to fail. These categories of lightweight design he also finds in architecture. He further explained that there are three types of lightweight design: system lightweight design, which involves creating structures with multiple uses and considering their entire life cycle; material lightweight design, which produces high-performance materials but often makes recycling or reuse significantly more difficult; and structural lightweight design, which focuses primarily on optimizing geometry. Julian believes that we need fatter structures and thereby more thermal mass in order to remain resilient in the face of climate change. However, when it comes to other safety measures—such as fire protection and noise insulation—he argues that we have gone much too far in adding mass. De-norming these aspects and reducing the millions of tons of material extracted might be worth accepting a slightly higher fire risk and the occasional sound of a neighbor’s voice. Having recently worked on the German Pavilion for Expo 2025 in Japan, he came back shocked by the overall quality of many of the structures, which barely followed the idea of combining form and structure. The most striking example, he noted, was the Qatar Pavilion: from the outside, it suggested an elegant membrane structure, but inside it revealed itself as a heavily over-engineered assembly of massive steel beams spaced every three meters and clad in plastic timber imitation. While in Japan on an excursion with his students, Julian also visited one of his favorite works: the remote Miho Museum with its unique hybrid suspension bridge. He was struck by the place’s extraordinary beauty, even as he noticed - and discussed with his students - certain inconsistencies in its structural logic. For Julian, intense debates between architects and engineers are essential to creating truly beautiful structures. lightness² the state of being light in color or shade He recalled with a certain pain his first experience working on an Expo, back in Shanghai in 2010. For the Norwegian Pavilion, he and the engineers from sweco developed a wood–membrane hybrid structure designed to be dismantled and reused after the event. After intense material sampling the client chose the far more expensive PTFE fabric for the membrane, beautifully translucent and offering a pure white that PVC-coated polyester simply cannot achieve. But when the clients realized at the opening of the expo that the interior was too bright for the exhibition, they turned (without asking) to the only paint that can adhere to a Teflon-based membrane and coated the entire roof. From the inside, every brushstroke was visible, and the lightness and elegance of the material was lost, before Julian and his team could suggest an alternative solution. But when the clients realized the interior was too bright for the exhibition, they turned to the only paint that can adhere to a Teflon-based membrane and coated the entire roof. From the inside, every brushstroke was visible, and the lightness and elegance of the material was lost. In another more recent project at Str.ucture, Julian and his team inserted a new ceiling into a former church to convert the space into a day-care center. The ceiling consists of inflated ETFE cushions, which create a delicate play of light as the colors of the stained-glass windows softly reflect across the surface of the bubbles. When discussing the potential span of inflatable structures, Julian defended what is often dismissed as a utopian vision: Buckminster Fuller’s proposal to place a dome over Manhattan. Fuller’s idea was based on a simple premise: While the dome itself would cover a vast area, the total surface of the buildings beneath it was roughly 80 times larger. By enclosing the city, all of that surface would no longer need individual weather protection, resulting in enormous savings in material and mass. lightness³ being carefree or feeling without burden Julian recalls a sense of lightness when working with his wife, an artist who explores physical phenomena. He vividly remembers the moment they released a weather balloon into the sky, fitted with several GoPro cameras and destined to burst at high altitude. Using GPS tracking, they eventually recovered the balloon and viewed the footage through a Google Cardboard—an early prototype of VR glasses. Looking back, he feels that his recent work on the German Pavilion with LAVA Architects was especially meaningful, in some ways closing the circle that began with his first Expo dilemma. The age of lightweight design as pioneered by Frei Otto and his generation may have faded, but its fundamental ambitions have not disappeared. Julian and his office are keeping its core values alive through new tools and strategies that reposition minimal impact design as a viable philosophy for the current state of our built environment. Get full access to lllightness at lllightness.substack.com/subscribe [https://lllightness.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_4]

6. The Photographer: Michael Wesely

In this episode of On Lightness, I have the pleasure of speaking with the visionary photographer Michael Wesely. We talk about his breathtaking year-long exposure photographs, how he became the godfather of this unique art form, and how his work reshapes our perception of time, space, and the built environment around us. It was a refreshing change to explore lightness through the lens of a photographer, expanding the field of this podcast into new territory. This episode was moderated and produced by Leon Hidalgo. The following article is meant as an informational extension of the podcast episode: Michael graduated from his photography studies in Munich with a curiosity for the state of his discipline. Early on, he began to question the often aggressive act of image-making — the idea that a photographer takes or even grabs a picture. He rejected this notion and from this resistance, a new method slowly crystallized — one that would define his artistic journey: the technique of Ultra-long Exposure Photography. Beginning with his five-minute portraits, Michael found a way to let the subjects create their own images. Lightness¹ the quality of having little weight Michael thinks lightweight structures barely exist in the contemporary architecture of Germany today. With his connection to South America he learned to appreciate the lighter and simplistic way of building - especially in Brasil, where he often traveled to. A Camera, he says, is a room, even in our phones there is this small dark room. In his early explorations he played with the composition of this space, which ultimately led him to his famous technique. He associates weight not just with physical mass but with effort and time. A long exposure, spanning five years, may result in an image of the same size as one taken in a millisecond, yet its weight is greater. It carries the gravity of duration. Today, technology allows Michael to travel much lighter, which he welcomes with a certain relief. It took him 10 years to implement his whole process from analogue into the digital photography realm. lightness² the state of being light in color or shade Light, to Michael, is everything. Photography, he reminds us, is born of light, time, and space. If one pays close attention, the performance of natural light throughout the day can be more exciting than any cinema, and it’s free. Light reveals thing, a certain sunlight glancing off a brick wall can reveal the quality of craftsmanship. If Michael’s photography were an architecture, it would be one that catches and tracks the sunlight throughout the day, a building that collaborates with the rhythms of the sun. Something closer to indigenous architecture, built with precise knowledge of the local natural conditions. lightness³ being carefree or feeling without burden For Michael, time is always relative. Its scale depends on perception, on how each of us forming our own reality of the world. What interests him most is the space between the visible and the invisible, the ambiguity in which imagination begins. That tension has always been central to his work. He’s fascinated by how time changes spaces, by the physical traces of the past that often go unnoticed. Remembering them, he says, helps us see how lucky we are to sharing the present moment. In one recent project, Michael played with the architectural scale of 1:100, but instead of using it to describe space, he imagined it as a measure of time. Thinking about how a place or a design might appear in a hundred years, he believes, is a valuable exercise not only for photographers but also for architects. This way of thinking, projecting time forward and backward, also defined a turning point in his own life. When Michael decided to create his first one-year exposure, he couldn’t know what would come of it. Looking back, that experiment became a foundation for everything that followed. Get full access to lllightness at lllightness.substack.com/subscribe [https://lllightness.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_4]