Vertical Urbanism Issue 4 II/2025

ISSUE FOUR II / 2025 THE MAGAZINE OF CTBUH

STEVEN HOLL AND STUDENT RESIDENTS DISCUSS MIT’S MOST CONTROVERSIAL DORM

MOSHE SAFDIE REFLECTS ON HABITAT, FROM STUDENT THESIS TO GLOBAL REALITY

PLUS COLUMNS: THE FIRST 3D-PRINTED WITH REBAR AND LEON KRIER’S FINAL SIGN-OFF

Publisher Vertical Urbanism is published by the Council on Tall Buildings and Urban Habitat (CTBUH).

ISSN: 2997-9463 (Printed) ISSN: 2997-9471 (Digital) Editorial Editor-in-Chief: Daniel Safarik dsafarik@ctbuh.org Executive Editor: Will Hunter will@will-hunter.com Managing Editor: Martina Dolejsova Associate Editor: Javier Quintana de Uña Advertising: Jody Cranford jcranford@ctbuh.org Production: Tansri Muliani Editorial Advisory Board Isabel Allen Reed Kroloff Editorial policy As a platform for interdisciplinary discourse on the sustainable densification of cities, Vertical Urbanism solicits articles from diverse fields of expertise.

Contributors are independent from CTBUH, unless explicitly stated otherwise. The opinions expressed by contributors are their own and do not represent CTBUH’s official stance nor carry its endorsement.

Submissions We welcome content ideas from our readers.

Please email submissions to dsafarik@ctbuh.org.

Cover The 3D-printed Tor Alva

by Benjamin Dillenburger and Michael Hansmeyer in the Swiss Alps.

IN TUMULTUOUS TIMES, cooler heads among us have long counseled that we consult the “classics.”

Get hip to some Hippocrates, vibe on some Vitruvius. Put the phones and tablets away. And yet—to face enormous climatic and socio-political challenges, we will need every kind of technology we can muster. The paradox of these clashing imperatives is woven throughout this issue.

We open with what may seem a heavy irony: that the last column published by the late critic Leon Krier—long the champion of the humanscaled and traditional, who passed away on 17 June—should appear in Vertical Urbanism (p. 11), amid robots printing towers (and doing many other things). But he is arguing not just against imposition of classicism by fiat, but for the reclaiming of civic architecture by the people it serves.

In our Venice Biennale coverage (p. 16 and p. 20), in both Carlo Ratti’s Intelligens and the national pavilions, techno-optimism is punctuated by just as many calls to more traditional, earthfriendly, and bio-based construction methods.

The riposte to the equation of classicism with humanism continues, as Steven Holl (p. 26), a hard-core Modernist—who takes fire from traditionalists as a “badge of pride,” and equates the same with fascists—argues forcefully to Will Hunter that his work, including the underappreciated Simmons Hall dormitory at MIT, is eminently humanistic. This is followed by mixed reviews from the students who live there.

Down the road in Cambridge, Casey Mack sits for an equally revealing interview with Moshie Safdie (p. 48), who has earned ample credit for his massive concrete structures that, despite their size, like Holl’s, take porosity as a central concept, and appeal to the human scale in the details.

That theme is echoed in Curitiba’s AGE 360 (p. 70), another concrete exoskeleton that has plenty of niches for smaller-scale socializing.

Perhaps the ultimate essay in concrete porosity is the open-air, 3D-printed Tor Alva (p. 110), the first to use rebar in its construction—who would have thought the next big thing in high-rise technology would be found in a tiny Swiss Alpine village?

And lest it be claimed that concrete is the material of choice for contemporary vertical urbanism, Mexico City’s Ferrocaril de Cuernavaca 780 (p. 82) , is in perfect steel-and-glass form, a flatiron shape that maximizes the value of its site with slimness. Not to be outdone, the timberconcrete hybrid Wood Up (p. 96) balances between classic Parisian proportions and a future-forward investment in renewable construction.

If anything, compiling this issue has shown us that humanity’s best hope is to grapple fully and honestly with complexity, contradiction, and carbon—calling all materials, all methods and all forms of intelligence to the front!

Daniel Safarik, Editor-in-Chief Vertical Urbanism 4 II / 2025

1

Agenda

Focus

Research

Insight

6 BULLETIN

26

DESIGN

122 PAPER

146 INSPIRATION

48

DESIGN

Terri Meyer Boake and Gary Strong examine the fire resilience of tall buildings, calling for a global recalibration of codes, materials, and assumptions.

Steven Holl reflects on the conceptual arc of his work, linking phenomenology and material experimentation across decades of practice.

128 PAPER

148 ARCHIVE

11 OPINION

The late Leon Krier’s last column: a critical take on government mandates and aesthetic values (below).

12 ESSAY

Sara Bronin argues for zoning reform for more equitable and functional urban environments.

16 INTERVIEW

Carlo Ratti discusses his curatorship of the 2025 Venice Architecture Biennale.

20 DISPATCH

Daniel Safarik and Beatrice Galilee report from the 2025 Venice Architecture Biennale.

Will Hunter interviews Steven Holl about MIT’s Simmons Hall and other experiments in vertical urbanism.

Casey Mack talks with Moshe Safdie, tracking the legacy of Habitat 67 to a new modular coastal development in China.

70

DESIGN

AGE 360, Curitiba showcases Triptyque and Architects Office’s biophilic tower.

82

DESIGN

96

TECH

Ferrocarril de Cuernavaca 780, Mexico City is a slim as a tower can be—“almost nothing” as Mies would say (below).

Wood Up, Paris presents LAN’s timber-concrete hybrid tower as a blueprint for low-carbon living.

110

TECH

Tor Alva, Switzerland unveils Hansmeyer and Dillenburger’s 3D-printed concrete.

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Varuni Jayasooriya and Matthew Adams analyze the thermal behavior of curvilinear towers through a detailed study of Toronto’s Absolute World.

144 DATA STUDY

CTBUH presents an analysis of tallbuilding activity and climate responsiveness across Europe and the Middle East (below).

Moshe Safdie revisits his formative Habitat 67 project through its archival traces and educational legacy at McGill University.

158 REVIEWS

Write-ups on: It’s About Time: The Architecture of Climate Change; Skyscrapers at the Roots in Montréal; Mies van der Rohe: An Architect in His Time; Sponge Park: Gowanus Canal; Architecture and Videogames (below); and Don’t Build, Rebuild.

166

CTBUH AWARDS

Explore the Award of Excellence Winners of the CTBUH 2025 Awards, which span across 20 countries.

170

LETTER FROM

Paco Bunnik sends a dispatch from Amsterdam, tracing the city’s evolving relationship to height, heritage, and housing.

L-R: CARL LAUBIN; CÉSAR BÉJAR; AS+GG; LIAM YOUNG

Towering inferno in Dubai; MVRDV launches a novel tool for low-carbon modeling; CTBUH’s European gathering in Amsterdam; NYU’s new Building Better Cities Collaborative.

Building Better Cit ies Coll aborat ive A new future-leaders program for people shaping tomorrow’s cities Developers, designers, and urban innovators collaborating on challenges.

Based in New York City.

Connected to a global network.

Focused on real-world impact.

Expressions of Interest now open. Learn more at sps.nyu.edu/bbcc

Schack Institute of Real Estate 3

Agenda

SARA BRONIN, who writes about zoning reform (p. 12), is a professor at The George Washington University Law School and founder of the National Zoning Atlas.

MARTINA DOLEJSOVA, the

communications manager at CTBUH, reports on the council’s European conference in Bulletin (p. 9).

Focus LEON KRIER, whose final opinion column appears (p. 11), was a prominent architect and theorist known for his critiques of modernism and advocacy of classical architecture.

GREG LINDSAY, who joins Daniel Safarik in interviewing Carlo Ratti (p. 16), is a non-resident senior fellow of MIT’s Future Urban Collectives Lab. CARLO RATTI, is an architect, engineer, and director of the MIT Senseable City Lab. He is interviewed (p. 16) about his curatorship of the Venice Biennale.

BENJAMIN DILLENBURGER,

GREG BOUSQUET, whose firm codesigned the AGE 360 tower in Curitiba (p. 70), is founder of Architects Office (AO), where he leads projects across Brazil, Europe, and South America.

MICHAEL SPEARPOINT,

who writes about the Pinnacle fire in Dubai (p. 6), is a fire engineer and research leader at OFR Consultants.

BEATRICE GALILEE, who reports from the Venice Architecture Biennale (p. 22), is the founder of The World Around, and was the first curator of architecture at the Metropolitan Museum of Art. WILL HUNTER, who launches NYU’s Building Better Cities Collaborative (p. 10), is executive editor of Vertical Urbanism and founder of the London School of Architecture.

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SANNE VAN DEN BURGH, who

introduces MVRDV’s new CarbonScape software (p. 7), is a partner at MVRDV leading innovation in sustainable urban development and digital tools.

who co-designed the White Tower (p. 110), is professor for digital building technologies at the Institute of Technology in Architecture, ETH Zurich.

MICHAEL HANSMEYER,

FRANCISCO BROWN,

who writes about a mixed-use project in Mexico City (p. 82), is Senior Editor at Metropolis magazine and a correspondent for Arquine in Mexico.

who co-designed the White Tower (p. 110), is an architect and programmer known for his algorithmically generated, materially intricate works.

STEVEN HOLL, who is interviewed about his vertical experimentation (p. 26) and pens the inspiration feature (p. 146), is founder of Steven Holl Architects and a tenured professor at Columbia GSAPP.

CASEY MACK, who interviews Moshe Safdie (p. 48) and reviews a book on cooperative housing (p. 160), is founder of Popular Architecture (POPA) and teaches at Pratt Institute. He is the author of Digesting Metabolism: Artificial Land in Japan 1954–2202 (2022).

FRANCISCO MARTINEZ SELLES,

whose firm LAN designed the Wood Up tower in Paris (p. 96), previously worked at Ateliers Jean Nouvel and OMA.

MOSHE SAFDIE, who features in conversation about Habitat Qinhuangdao (p. 48), is an architect, educator, urban planner, theorist, and author. A former apprentice of Louis I. Kahn, he is best known for Habitat 67 and a global portfolio of housing, cultural, and civic projects that balance humanism and density.

Research

Insight

MATTHEW ADAMS, who co-authors the thermal behavior study (p. 128), is an associate professor at the University of Toronto Mississauga.

PACO BUNNIK, who writes the letter from Amsterdam (p. 168), is chief urban designer in the City of Amsterdam’s Department of Urban Planning and Sustainability.

TERRI MEYER BOAKE, who co-authors a paper on fire resilience in tall buildings (p. 122), is a professor at the University of Waterloo.

She sits on multiple boards, including CTBUH’s Fire & Life Safety Committee.

GARY STRONG, who co-authors the fire resilience paper (p. 122), is chair of the UN-backed International Fire Safety Standards (IFSS) Coalition.

He leads the RICS fire group and chairs the CTBUH fire performance of façades working group.

VARUNI JAYASOORIYA,

who co-authors a paper on thermal behavior in curvilinear towers (p. 128), is a postdoctoral fellow at the University of Toronto Mississauga, with a Ph.D. in Environmental Engineering.

JAMES SOANE, who reviews It’s About Time: The Architecture of Climate Change (p. 163), is a director of Project Orange.

He is the author of several books on ethics and education in architecture.

MICHÈLE CHAMPAGNE, who

ISAAC WORK,

who authors the CTBUH regional data study on tall-building activity in Europe and the Middle East (p. 144), is building data coordinator at CTBUH.

BRAM MONSON, who reviews Sponge Park: Gowanus Canal (p. 164), works at Selldorf Architects, which is designing a project in the Gowanus Canal.

reviews Skyscrapers at the Roots at MAC Montréal (p. 161), is a graphic designer working across research, creative direction, and editorial design.

MICHAEL WEBB, who reviews Mies van der Rohe: An Architect in His Time (p. 158), is a Los Angeles–based design writer and author of more than 20 books on architecture.

JAMES DELANEY, who reviews Architecture and Videogames: Intersecting Worlds (p. 165), is the founder and of BlockWorks, a global design studio using Minecraft as an architectural medium.

LILIANE WONG, who reviews Don’t Build, Rebuild (p. 159), is professor of interior architecture at Rhode Island School of Design. She is author of Adaptive Reuse in Architecture.

Vertical Urbanism 4 II / 2025

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BULLETIN DUBAI, UAE

Michael Spearpoint A fire at the Marina Pinnacle tower in Dubai on the night of Friday 13 June 2025 has once again exposed the disturbing fragility of tall-building fire safety in the Gulf region. This is not the first such incident in Dubai Marina—and, on current trajectory, it won’t be the last.

Footage shared online shows the blaze beginning near the top of the 73-story residential tower around 9:30 p.m. Flames rapidly climbed the façade, with debris raining down and residents scrambling to evacuate. More than 3,800 people were cleared from 764 apartments. Though no fatalities have been reported, the building sustained serious fire and smoke damage, and many residents have since returned only briefly to retrieve personal items from scorched interiors.

Dubai Civil Defence claimed the fire was brought under control within six hours. However, daylight footage of the fire posted online—well past the 5:30 a.m. sunrise—suggests a longer duration than officially stated. This timeline discrepancy is not the only unanswered question. Most disturbing is the near-total absence of alerts.

Residents have described an evacuation that relied not on alarms or coordinated instructions, but on guesswork, smell, and messages from friends.

One resident on the 28th floor recalled: “The fire alarm system never went off. We didn’t know there was a fire until a friend messaged me an hour later.

My wife and I almost didn’t make it out.

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UPDATE NEWS

Burning Questions Remain About the Fire-Struck Pinnacle

The fire at the Marina Pinnacle in Dubai, UAE, exposes suspected multiple system failures.

The emergency staircase was full of smoke. We had to use the elevator.

When we reached the lobby, it was also filled with smoke. If it wasn’t for people screaming and pointing us in the right direction, we could’ve died.”

A resident from the 24th floor offered a similar account, noting the stairwell was too smoke-filled to navigate. Another from the 47th floor was only alerted when a friend from a neighboring tower called to check on her; she evacuated with her daughter, pets, and no official guidance. Still another family, departing through thick smoke, described moving shoulder to shoulder, guided only by the person ahead.

These accounts suggest multiple system failures. Whether or not sprinklers were installed—and footage suggests they may have been—their effectiveness is unclear. While online images appear to show ceiling-mounted sprinklers and smoke or heat detectors in both corridors and apartments, it’s unknown whether they were connected to a central alarm or operated independently.

If alarms did sound at all, they appear not to have reached many residents.

It also remains uncertain what caused the fire, where exactly it started, and how it spread. Visual evidence and

anecdotal reports indicate the blaze may have originated on a high floor, but smoke was reported in stairwells as low as the 24th floor. That smoke could breach stairwells—normally protected by pressurization and compartmentation—raises serious concerns about the building’s internal fire safety strategy. At this time, no official information has been released regarding the building’s fire detection, suppression, smoke control, or evacuation systems.

One hypothesis gaining traction online, though unconfirmed, is that the building was clad in aluminum composite material (ACM) with a polyethylene (PE) core. This type of cladding has been linked to numerous façade fires in the region. The pattern of vertical fire spread at Marina Pinnacle, and the visual similarity to earlier cases, makes this a credible scenario.

Despite the dramatic fire, a large number of people were able to evacuate —many via lifts. It’s not yet clear whether this was intentional, but it likely contributed to the safe outcome.

This, too, raises questions. Conventional fire guidance discourages elevator use during emergencies.

However, as was discussed at the CTBUH 2024 International Conference in London, protected fire-rated elevators may in fact be essential, particularly in very tall buildings and for residents with limited mobility.

In this case, one resident later noted that she was forced to relocate temporarily to another building from her wheelchair-using husband—implying they may have had to evacuate separately.

That such basic evacuation logistics are left to improvisation underscores the wider failure.

Publicly available data on the Marina Pinnacle remains limited.

The CTBUH Skyscraper Center describes it as a 280-m-tall, all-concrete structure completed in 2011, equipped with ten high-speed lifts and mechanical and parking floors. A retrofit program reportedly began in 2025, but no details have been released on whether fire safety systems were part of that effort.

The full story of what happened at Marina Pinnacle may never be known.

But its outline is already familiar. This is a region that has experienced multiple façade fires in residential towers with similar characteristics. The materials and design strategies involved are well known.

The regulatory questions are not new.

And yet the cycle repeats.

The Marina Pinnacle fire starkly illustrates many of the concerns raised

by Boake and Strong in their essay, “Fire Safety in Tall Buildings: Lessons and Questions Post-Grenfell” also published in this issue (page 122). They argue that too many tall buildings are governed by a fire safety regime built on presumption rather than proof, and shaped by reactive rather than proactive codes.

Unless that changes, the next blaze is not a matter of if, but when.

ROTTERDAM, NETHERLANDS

New Industry Tool to Combat Embodied Carbon

ANDRES LARIN / WIKIMEDIA

Sanne van der Burgh

Completed in 2011, the 77-floor Marina Pinnacle has 764 residential and commercial units.

Fundamental questions remain unanswered: Was the building designed for simultaneous, phased, or stay-put evacuation? Were sprinklers present, and if so, did they activate? Why did smoke infiltrate protected escape routes?

How did residents know—or not know— when to flee?This is not a one-off. In 2015, a kitchen fire at the same building led to a minor evacuation. This was quickly extinguished and praised at

the time as “super-efficient.” This time, efficiency gave way to chaos.

Tall-building fire safety is not a checklist—it’s an integrated system.

It depends on layers: materials, suppression, detection, communications, management. When one fails, the others must hold. When multiple layers collapse—as they appear to have here— residents are left to rely on instinct, luck, or strangers yelling from across the street.

MVRDV is launching a new tool called CarbonSpace—a fast, free method for estimating the embodied carbon of a building from the very earliest stages of design. Before the models are detailed.

Before the structure is locked in. While there’s still time to make meaningful change. We’re offering it openly, because we believe the climate crisis can’t be tackled in isolation.

What problem are we trying to solve?

It’s well known that the construction industry is responsible for 39% of global greenhouse gas emissions. What’s less discussed is that most of those emissions are already baked in by the time we get our first carbon numbers.

Today’s workflows depend on detailed BIM models and product declarations. By the time the calculations arrive, the major decisions—structure, systems, form— have already been made. The numbers may be accurate, but they come too late to Vertical Urbanism 4 II / 2025 AGENDA

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MVRDV

MVRDV’s new CarbonSpace tool lets you target carbon where it matters most—early, intuitively, and before design decisions lock in.

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Vertical Urbanism 4 II / 2025 AGENDA

elements that feel “sustainable”—visible materials, interior finishes, smart swaps —when the structural systems beneath them often account for the majority of embodied emissions. We’re looking in the wrong places.

CarbonSpace is our answer. It’s not a verifier or certifier. It’s a rapid, intuitive tool for early-stage carbon thinking— designed to inform decisions, not document them after the fact.

You start with whatever you have: a sketch, a volume estimate, a 3D model, a brief, even an invoice. CarbonSpace links those inputs to a transparent, internationally representative database —based on a simplified version of Okobaudat—and returns quick, realistic estimates. You can compare structures, test façade strategies, weigh design timelines. Like cost planning, the estimates move from rough to refined.

The goal isn’t perfection—it’s perspective.

We want to help designers build a kind of carbon intuition: the same instinct we develop for cost, complexity, or massing. A slab feels heavy. A biobased

wall feels lighter. CarbonSpace helps make those instincts visible and testable —early, often, and comparatively.

Using CarbonSpace across our own portfolio has already shifted how we think. First: structure matters most.

Foundations, slabs, and cores are the carbon giants, due to their cement and

MVRDV

steer design. This is the industry’s blind spot: we measure instead of design. We talk about impact, but chase precision.

And we often reward low-carbon claims —on paper—without verifying their delivery in construction.

We’ve also made the conversation harder than it needs to be. Even across projects in the same firm, basic metrics like gross floor area are defined differently by country, making honest comparisons nearly impossible. In one market, our Markthal project performs well; in another, it doesn’t—because of how the baseline is calculated. The result is a kind of carbon confusion, where no two numbers speak the same language.

Meanwhile, we tend to focus on

CarbonSpace can quickly calculate your building’s performance with different cladding materials—for instance MVRDV’s famous Valley, now finished in straw.

steel content. Interior partitions, ceilings, and finishes matter far less. Ironically, the things we obsess over as designers often have the smallest impact.

Second: weight is a surprisingly effective proxy. In general, heavier buildings are higher-carbon buildings.

That doesn’t make all light buildings good, or all heavy ones bad—but it offers a fast shortcut for thinking about emissions. We’ve started to feel carbon the way we feel calories, or cost—and that’s the point.

Third: the math is sobering. To meet the EU Green Deal targets by 2030, we need to reduce embodied carbon by around 3 kgCO2/m2 per month, every month, for the next five years.

Our lowest-carbon projects so far are lightweight, biobased, renovations— or all three. But even then, it’s not easy.

We’re trying. But we can’t do it alone.

The building industry is built on proprietary models, closed systems, and competitive data. But the climate crisis doesn’t care about NDAs. That’s why we’re sharing CarbonSpace freely— because the only way to accelerate change is to build a collective carbon community.

CarbonSpace is not a silver bullet.

But it does help bring the right people around the table—sooner. It supports transparency. It encourages comparison.

And it gives us a shared language to talk about embodied carbon while it still matters: during design.

We’re inviting you—designers, engineers, clients, researchers—to join us.

Use CarbonSpace. Break it. Improve it.

Share what you learn. Help us build a tool that works not just for our office, but for the profession as a whole.

Our beta partners already include engineering firms, research institutes, universities, Green Building Councils, and CTBUH, which is using the tool as the engine behind its Developer’s Carbon Commitment.

Because carbon literacy should be a design skill. Because transparency should be standard. And because the future won’t be low-carbon by default —we’ll have to design it that way.

CarbonSpace will be publicly released

Theory of Change diagram for NYU’s new Building Better Cities Collaborative fellowship.

NEW YORK CITY, USA

New Future Leaders Program for City Change-Makers Will Hunter The theoretical physicist Geoffrey West once wrote that cities are both the engine of humanity’s salvation and its destruction. As they grow, their resource demands rise exponentially—but so does their capacity for innovation.

Why? Because density creates more collisions: more ideas, more exchange, more possibility. But as West also notes, these innovations require new systems of cross-disciplinary collaboration— structures that can turn complexity into creativity, and civic ambition into executable strategy.

That’s the founding logic of the Building Better Cities Collaborative (BBCC), a new two-semester fellowship at NYU’s Schack Institute of Real Estate.

BBCC is designed for high-potential, mid-career professionals—architects, planners, developers, technologists, policymakers, and others working across

the built environment. This is not executive training—it’s a hybrid platform: part talent accelerator, part collaborative R&D lab, part civic catalyst. Fellows commit one day per week to an intensive curriculum that blends strategic foresight, systems thinking, applied research, and peer exchange. Participants take part in studio sessions, masterclasses, and monthly reviews with public officials, investors, designers, and policy thinkers.

BBCC is hosted in partnership with NYU’s Urban Lab and connects to a broader intellectual ecosystem across the university’s institutes and research centers. Fellows contribute to a shared research agenda and produce published outputs that inform policy, strategy, and long-term urban thinking. Graduates receive NYU alumni status and join a cross-sector network of peers committed to the civic project of city-making.

For CTBUH members, this crossdisciplinary approach—linking urban foresight, innovation strategy, and built form—offers a rare opportunity to deepen exactly the kind of integrative thinking our cities now demand. BBCC is structured to align with R&D, innovation, and leadership budgets, with discounted rates for small practices to encourage the diversity of fellows.

The pilot cohort launches Fall 2025.

Expressions of interest are open now.

For more information please visit sps.nyu. edu/bbcc or email w.hunter@nyu.edu.

Vertical Urbanism 4 II / 2025 AGENDA

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Europe Gathers to Rethink Urban Density Martina Dolejsova in September at carbonspace.earth.

CTBUH held its 2025 Europe Conference, “Different Densities: The quest for carbon-neutral cities in Europe,” in Amsterdam on 3–4 June, and in Rotterdam on 5 June. With an incredible turnout of 171 attendees from 50 cities and 22 countries across Europe, Asia, the Middle East, and North America, delegates joined CTBUH for thought-provoking presentations, stimulating conversation, astounding off-site tours, and multiple networking opportunities.

Kicking off the event, CTBUH leaders came together on 3 June at the UNS offices to share the latest regional updates and activities. In the afternoon, off-site tours in conjunction with the conference showcased projects like the Valley (see Vertical Urbanism Issue I), booking.com City Campus, and the opening networking reception location in the newly reopened De Nederlandsche Bank (DNB).

Offering more than just a chance for connecting at the reception, the DNB embodied the very ideals at the heart of this year’s conference. After nearly five years of renovation, the historic headquarters exemplifies how legacy buildings can be transformed to meet carbon goals while serving the community.

On 4 June, the core conference was held in the repurposed De Duif church (1858) in the heart of Amsterdam, with sessions packed with influential case studies, and conversations emphasizing how we can create supportive design decisions for the environmental concerns this region (and the world) are facing.

As part of the opening, the exciting announcement that CTBUH and Stichting Hoogbouw are forming a partnership to promote best practices and support better density was shared with the audience. CTBUH Chairman 10

Vertical Urbanism 4 II / 2025 AGENDA

Shonn Mills and Erik Faber, President of the Board of Stichting Hoogbouw, signed a ceremonial document for this new chapter with the Council.

Other highlights from the day include the CTBUH City Advocacy Forum participants Paco Bunnik, Urban Design Supervisor at City of Amsterdam, Do Janne Vermeulen, Architect/Director at Team V Architecture, Gwyn Richards, Planning and Development Director at City of London, and Peter Cachola Schmal, Director of Frankfurt’s Deutsches Architekturmuseum (DAM), who spoke about retrofitting, preserving cultural identity while modernizing, and creating toolkits for informing planning decisions.

Keynote speaker Ben van Berkel, Founder of UNS, closed out the day with the wisdom of “Density and value are connected by mixing the right programs into how you densify.

By rethinking density, we can design adaptable, human-centered environments that connect deeply to their context and improve quality of life.”

Continuing the conversations on 5 June at the MVRDV offices in Rotterdam, there was a half-day of presentations and panels on transformative projects and environmental strategies.

Sanne van der Burgh at MVRDV

(see the feature on the previous page) highlighted the complexity of calculating embodied carbon and shared the exciting current CTBUH and MVRDV partnership to advance this work.

As a complement to these discussions, off-site tours were led by speakers Emiel Arends, Senior Advisor on Urban Affairs at City of Rotterdam (City Walking Tour), Haakon Brouwer, Architect at Dam & Partners Architecten (De Zalmhaven), and Robert Winkel, Founder and Lead Architect at Mei Architects and Planners (SAWA, a timber high-rise), giving participants deeper insights into designing for carbon goals and learning from inspiring real-life examples to better the future of our cities.

We left the Netherlands with fresh perspectives and renewed momentum for shaping low-carbon, high-impact cities.

Read conference speaker Paco Bunnik’s Letter From Amsterdam on page 170.

CTBUH

CTBUH

Ben van Berkel (right), Founder of UNS, gave a keynote at CTBUH’s Amsterdam conference.

OPINION TRUE DEMOCRATIC ARCHITECTURE IS CIVIC, NOT POLITICAL LÉON KRIER Earlier this year, the US President once again decreed that new federal buildings ought preferentially to reflect the classical architectural traditions of the nation. The news has predictably reignited a furor— between modernists and traditionalists, Democrats and Republicans, tastemakers and citizens. But to frame the question of architectural style as political preference is already to mistake the problem.

There is no democratic or totalitarian architecture, no progressive or reactionary architecture. There is only architecture—or its absence. And for the last 70 years, what has replaced architecture is not neutrality, but aggressive ugliness: an abyssal, degrading, destructive force.

Despite being touted as the architecture of democracy, modernism has never taken the pulse of popular feeling. It has never tried to win the hearts of citizens. It has been imposed—by academia, public officials, industrial lobbies, media systems, and bureaucratic fiat—as the only legitimate expression of modern life.

This is not new. In 1990, I was invited to Dresden to discuss the fate of the bombed-out Altstadt. A delegation of prominent citizens called for the reconstruction of the historic Neumarkt and Frauenkirche. Except me, the assembled experts—including Gerkan, Otto, Behnisch—sneered. The newspapers ignored the citizens’ plea. But through 30 years of persistence, they prevailed: the ensemble nears completion today.

This is not an isolated story—it repeats in Berlin, Potsdam, Frankfurt, Nuremberg.

The rift between the democratic public and the architectural profession has rarely been so exposed. In 2020, a Harris Poll commissioned by the National Civic Art

Society found that 72% of Americans— across party lines—preferred classical to modernist federal architecture.

That such overwhelming consensus exists in a country otherwise polarized on every issue should tell us something.

What it tells us is that people, of all backgrounds, still seek beauty. They make aesthetic judgments instinctively—through love or repulsion, admiration or dismay.

And yet, the aesthetic preferences of the public are systematically ignored.

The so-called “architecture of democracy” is not a mirror of public will. It is the projection of a professional monopoly—uninterested in tradition, contemptuous of human scale, and functionally complicit in ecological ruin.

Even the language of sustainability has become a diversion. Green suburbs, green skyscrapers, green transportation— eco-chitchat that postpones collapse without altering its course. The so-called “sustainable city” is a utopian fabulation.

What exists, materially and historically, is the traditional city: a compact, walkable, polycentric model refined over centuries.

It is the only relatively sustainable settlement form humanity has produced.

But it is not being taught, legislated, or replicated. It is actively dismantled.

So no, the problem is not whether a president favors Doric columns.

The problem is that the Common

Good—the shared, aesthetic, civic space of the city—has been surrendered. It has been surrendered to technocrats, to global capital, to architectural illiteracy.

And this is not confined to the United States. The postwar international buildings of the UN, NATO, EU, IMF—stand as mute monuments to bureaucratic anonymity. Their vast size, hostile symbolism, and disregard for urban context do not inspire civic trust. They project neither legitimacy nor meaning.

They are the architecture of no one.

In a truly democratic society, buildings of public import would reflect the values and affections of the people who live with them. But that would require a profession willing to listen, and a politics capable of imagining a city beyond spreadsheets and renderings. Let me be clear: the return to traditional architecture will not come about through popular vote or partisan decree. It will come by fate—by overwhelming necessity.

We live now in a capital moment. The fantasy of permanent economic growth, on which modernism and progress narratives were built, is ending. Without cheap fossil energy, there will be no high-tech suburbia, no hyper-modern building industry. The house of cards collapses.

The architecture of the Common Good is not political. It is civic. It is aesthetic. It is formed in squares and streets, where religious, political, and linguistic differences coexist. And it must be recovered—not through diktats from above, but through a cultural act of reconstructing what we once knew.

A beautiful public realm is not a luxury. It is a foundation for democracy itself. Without it, democracy fails.

Vertical Urbanism 4 II / 2025 AGENDA

11

ESSAY The mid-century optimism of the May Company mall once defined San Diego’s suburban dream.

Now that model has collapsed, and the city has introduced a mixed-use zoning code to usher in an urban rebirth, writes Sara Bronin.

Why is sprawl so common, even in large American cities? Opportunities to “go vertical” are often heavily constrained by arcane regulations that implement the most consequential local government power: zoning.

Zoning has been adopted by tens of thousands of local jurisdictions, each establishing their own rules for future growth through a combination of a zoning text outlining rules for specific districts and a color-coded zoning map showing the district assigned to each plot of land. Zoning codes are often difficult to decipher, and their impacts little-understood—even by the local officials that oversee them.

That may well be why zoning codes are rarely significantly changed: once adopted, they stagnate for decades.

Yet rezoning an underutilized site for greater verticality, and a greater mix of uses, can offer tremendous benefits. The backstory of rezoning the site of one the first malls in the country illustrates how one highly urbanized but fairly low-lying city—San Diego—has moved to shed the pro-sprawl approach embedded in its zoning code.

12

Vertical Urbanism 4 II / 2025 AGENDA

The roots of this approach can be found in a city council meeting in the summer of 1958. The fourth item on the agenda that long-ago day involved a petition to rezone four large empty lots in rural Mission Valley—­an 80-acre (32-ha) combined parcel that sat between the highway and the San Diego River, 4 miles (6.4 km) north of the city’s bustling downtown. City officials had placed them in a residential zone, with the hope they might be subdivided to satisfy pressing housing needs. In the preceding two decades, the city had more than doubled in population. This rapid growth tracked along with military investments in camps, training facilities, hospitals, an air station, and a major naval base.

That morning in June, proponents of the rezoning made the case that these 80 acres should be assigned to a zone permitting a limited array of commercial uses. Speaking first for the property owners, attorney Walter Ames stated that his client, the May Company, hoped to build a shopping center on the land.

He presented a list of supporters and stated that the mall—­one of the first in

the country—­would draw tourists, benefit the economy, and generate employment opportunities. A vice president of the May Company reinforced this message, adding that the company planned to spend US$35 million on improvements and that it had thoroughly accounted for traffic and flood impacts. Commercial property owners and the labor council also testified in favor of the rezoning.

Not everyone agreed that it would be a good idea. The meeting became so contentious that the mayor of San Diego, who was running the meeting, ordered the bailiff to remove objectionable signs.

Once order was restored, the testimony continued. Opponents noted that the rezoning would irreversibly change the river channel and destroy open space.

But the most prescient words came from Guilford H. Whitney, a downtown five-and-dime merchant who argued that the new mall would hurt downtown businesses. He pointed to the decline of Fresno’s downtown after the development of a similar shopping center, predicting, “If we build another central city only four minutes away from

CLASSIC SAN DIEGO

Above— Original advert for Mayco mall in Mission Valley, promising convenience, modernity, and a bright future for San Diego’s growing population.

downtown, we may end by having a slum business district in what is now our central area.” Hamilton Marston, a downtown department store owner, apologized for sounding as if he wished to stifle competition but, like Whitney, urged city leaders to punt on this decision until they could finalize a comprehensive land use plan.

These concerns notwithstanding, excitement about the proposed mall carried the day, and the city council took steps that led to unanimous approval of the rezoning. The decision changed San Diego’s trajectory. More malls followed, including Fashion Valley, which came up next door to the May Company complex in 1969.

Vast parking lots encircled the stores, creating complete separation from the residential areas nearby. Driving became the only way to reach the shops. As Walter Ames had predicted, many of the malls’ patrons were tourists, including some who drove in from Mexico. Meanwhile, downtown suffered.

Whitney’s department store fell in 1965, while the handsome, six-story Marston building was demolished in 1969.

Fifty years later, trends have reversed. Many urban downtowns have roared back, and San Diego’s downtown has attracted new businesses and housing, along with entertainment in the historic Gaslamp neighborhood, popular with residents and tourists alike.

Meanwhile, several of the outlying malls have aged poorly, falling from novel attraction to generic big-box sprawl.

The departure of Saks Fifth Avenue in 2010 was a blow for Fashion Valley, while in the original May Company parcel, the last true department store, Macy’s, shuttered in 2017, leaving only its home goods division and an outlet.

Even 75%-off bargains in its final days reportedly attracted only a few shoppers.

Spurred by that closure and other events, members of the San Diego City Council—­the body that rezoned for single-use retail sprawl back in 1958 —­recently decided to take a closer look at the city’s outdated shopping centers.

Reviewing neighborhood plans calling for a mixed-use rezoning, they explored how “infill” development—making use of the empty space occupied by parking lots—could knit the community together.

Vertical Urbanism 4 II / 2025 AGENDA

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Vertical Urbanism 4 II / 2025 AGENDA

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They solicited more public input. Finally, in 2019, the council adopted a new section of the zoning code, unanimously undoing what its predecessor body CLAIREMONT MESA had done 61 years prior.

The new code established two mixed-use districts and mapped them on many large, underutilized LINDA VISTA sites, including the malls of Mission Valley centered on the area’s light rail station. It articulated the purpose for these districts: to offer a mix of housing and jobs, to reduce automobile dependency, to increase transit use, and to encourage a walkable environment. To achieve these aims, the code streamlined permitting, allowing for speedier approvals of proposed construction.

The mixed-use district assigned to the May Company site allows for office, industrial, and retail uses as the primary land use, with housing as a secondary use. While the previous version of the code allowed some mixed-use buildings, the permitting process was costly and timeconsuming, requiring many stages of review and public hearings. The new code freely permits most mixeduse projects in this area, so long as developers abide by certain guidelines.

Many of these guidelines relate to the building “frontage,” or the façade of the building abutting the street.

UPTOWN The guidelines require that frontages be active and transparent, meaning entrances belong on the ground floor, must be oriented toward a public sidewalk, and must include Above— Current zoning some combination of arcades, porches, map of Mission balconies, awnings, trellises, or other Valley, San Diego: “activation elements.” The code also a new patchwork for a new era— requires pedestrian entrances, paths, mixed-use districts MIDWAY-PACIFIC HIGHWAY and connections, as well as buffers (like now overlay former mall sites, inviting landscaping) shielding parking spaces density, transit, and from view. It breaks up megablocks, walkability where calling for paseos—defined as pedestrian parking once ruled. accessways connecting streets, plazas, alleys, parks, and other amenities— ­and bicycle accessways for every 2 acres (0.8 ha) of lot. Together, these guidelines better connect buildings in this area to the street, and create a walkable and OP-1-1

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that the new development fills in vast, unsightly parking lots and integrates into surrounding neighborhoods better than 15 the single-use retail that came before.

Excitement about the economic value created by the rezonings has generated MID-CITY:KENSINGTON-TALMADGE activity on neighboring properties, too.

The owners of a 200-acre (81-ha) former golf course site straddling the San Diego River, recognizing the spillover value MID-CITY:NORMAL HEIGHTS created by the rezonings, successfully petitioned the city council to approve a site-specific master plan for an integrated live-work community centered around a riverwalk that will restore water access to the community. The council granted zoning approval for the construction of 4,300 housing units (10% of them affordable), 1 million sq ft ( 92,903 m2) of office space, and more than 150,000 sq ft (13,935 m2) of retail space, all connecting to a new light rail station NORTH PARK MID-CITY:CITY HEIGHTS and bike andIndex Map pedestrian paths. The first phase of the project broke ground 48 49 in 2023, a strong signal that47San Diego’s 44 46 45 rezonings will42generate big returns— 43 ­not just financial, but social, too.

41 39 40 Unfortunately, like 37rezonings 35 36 38 council’s land use and housing those in San Diego bikeable environment in an area 33 are 31 32 34all too rare. committee, she also led efforts to Underutilized malls are previously designed for drivers alone.

26 27 28 and 29 vacant 30 eliminate parking mandates near transit just one type of outdated development Councilwoman Vivian Moreno 21 22 23 24 25 infrastructure, so developers do not have ripe for transformation.

Yet zoning helped lead the charge for these changes.

18 19 20 14 not 15 been 16 17 to build expensive parking garages in codes have revisited to enable Rather than trying to downplay 12 malls, 10 11 13 areas where people don’t need them. new possibilities for much less ARK the impact of rezoning, as some As she and others keep a watchful other types of9 wasteful, sprawling politicians do, she made a compelling 6 7 8 eye, these neighborhoods are already development.5 I hope my book offers public case for them. The website for 1 2 3 4 being remade. Perhaps most significantly, people insights about understanding her last reelection campaign explained SCALE: 800 the rezonings have GRID spurred a US$290 the levers of power contained in zoning how the San Diego upzonings—­ Services Department DATE: 06/13/2025 03:25:25 PM million sale of two Mission Valley codes, so that they have confidence in changes to code designed to foster mall parcels to an investment firm their power to change them—for good. more development—­will help to eager to build a mixed-use development.

This article was adapted from Chapter address the housing crisis, which While plans have yet to be released as 1 of Key to the City: How Zoning Shapes she called “one of the central challenges of this writing, the city’s code will ensure Our World (W.W. Norton 2024). of our generation.” As chair of the city RS-1-1

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INTERVIEW

Leader of MIT’s Senseable City Lab, Carlo Ratti discusses his curatorial strategy for the 2025 Venice Architecture Biennale with Greg Lindsay and Daniel Safarik.

Greg Lindsay The Biennale has never addressed technology so directly.

With your appointment as curator, it seemed inevitable that intelligence —especially artificial intelligence— would be central. Was this always your intention, or did you have to persuade the organizers?

Carlo Ratti The Biennale isn’t only about technology. Of course, technology is present, but Intelligens—with its subtitle Natural. Artificial. Collective.— explores how these different forms of intelligence can be brought together.

Tackling today’s most urgent challenges demands adaptation, and that requires more than digital tools. It calls for natural intelligence, collective wisdom, and the ways we’ve shaped our built environment for thousands of years.

Daniel Safarik You’ve spelled “intelligens” to highlight its Latin root—gens, or people. Does that imply a corrective to tech-centric thinking?

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CR Exactly. Most Biennales use two titles, one in Italian and one in English.

We chose just one—rooted in Latin— to emphasize multiplicity. Today, when you say “intelligence,” people think of ChatGPT or large language models.

But we wanted to broaden that: to remind people that architecture has always drawn from many kinds of intelligence—vernacular, communal, intuitive—and that we must harness all of them to adapt to a changing planet.

GL This year’s Biennale is the largest ever, and your open call welcomed submissions from across the world. Why take such a radically inclusive approach?

CR Biennales are typically top-down —curators invite people from their networks. We wanted to flip that model and try something more open and bottom-up. So we held salons around the world, inviting people to contribute.

The open platform received thousands of responses. It was overwhelming—

but also deeply rewarding. We discovered voices we might never have found otherwise: recent graduates, practitioners from across disciplines, people working in remote contexts.

I’m reminded of Umberto Eco’s idea of the opera aperta—an open work that evolves through collective input.

That’s how we approached this Biennale.

DS You’ve revived the Speakers’ Corner, first introduced in 1980.

This time it’s curated by Christopher Hawthorne, former Chief Design Officer of Los Angeles. What role does criticism play in your vision for the Biennale?

CR The Speakers’ Corner is located at the heart of the Collective Intelligence section in the Arsenale. Every day it hosts conversations—some via the open call, others involving locals, students, or major organizations like C40 and the UN. Typically, architecture biennales open with a few conferences and then revert to architects speaking to

VENICE BIENNALE

architects. We wanted to broaden the conversation: to make it ongoing, accessible, and interdisciplinary. That’s where collective intelligence begins.

GL Adaptation is a central theme.

Are there particular projects that exemplify how natural, artificial, and collective intelligence come together?

CR Rather than highlight individual projects, I’d emphasize the networks behind them. Many projects are collaborations among architects, scientists, social researchers, artists, chefs, and more. Take Canal Café— a collaboration between architect Liz Diller, a hydrologist, and culinary experts to purify lagoon water and turn it into drinkable coffee. Others explore water through big data, agricultural practices, or indigenous knowledge. The point is not just the content, but the connections.

And this ethos extended to national pavilions too. Many curators aligned

Above— Carlo Ratti photographed in Venice.

with our adaptation theme, so the whole Biennale has become an ecosystem of interlinked investigations.

GL You’ve said that the Biennale should be a place for creating new knowledge, not just showcasing existing work. What’s the long-term goal? Is there a structure to continue the conversations started here?

CR Yes—and that’s a key shift. In the past, biennales were about display. But today, you can see any project online the moment it’s built. So this Biennale is about co-producing knowledge.

Architecture must play a role in responding to climate change, rising sea levels, and social fragmentation.

We launched a Manifesto for Adaptation, signed by over 250 contributors. The Biennale becomes a platform for action—an ongoing dialogue rather than a periodic event.

DS

Of course, much has changed Vertical Urbanism 4 II / 2025 AGENDA

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politically since you began planning.

The 2024 US election—and rising nationalism elsewhere—have reactivated some of the colonial and imperial legacies that previous Biennales sought to critique. Has this altered how the exhibition is received?

like Piazza San Marco and at local universities. Venice itself is a perfect case study—an ancient feat of geoengineering and adaptation. It transformed an uninhabitable lagoon into a thriving city. That spirit of transformation is exactly what we need today.

CR Certainly, we didn’t foresee all of these shifts. But they only make adaptation more urgent. If political actors deprioritize mitigation, then adaptation—how we live with change —becomes all the more essential.

Our goal remains the same: to convene many forms of intelligence to navigate uncertainty together.

DS Rather than being an ironic location for a climate-focused exhibition, Venice may be the most appropriate.

CR We lost almost half the exhibition space, so we decided to turn the entire city of Venice into a living lab. You’ll find installations not only in the Arsenale and Giardini, but also in public spaces

Right— At Canal Café, Diller Scofidio + Renfro collaborate with scientists, chefs, and hydrologists to filter water from the Venetian lagoon—serving purified coffee as both provocation and proof of adaptive design.

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GL How is the Arsenale organized?

Does each section correspond to one type of intelligence?

DANIEL SAFARIK

GL The Giardini’s Central Pavilion is closed this year. How did that affect your curatorial approach?

CR Absolutely. One project—Terms and Conditions + The Third Paradise Perspective—involves ETH Zurich climate scientist Sonia Seneviratne, Transsolar engineers, and artist Michelangelo Pistoletto. It imagines Venice’s climate 50 or 100 years from now. Venice is fragile, but it’s also a symbol of resilience. That duality is central to this Biennale.

DANIEL SAFARIK

Right— In Terms and Conditions + The Third Paradise Perspective, climate scientist Sonia Seneviratne and artist Michelangelo Pistoletto imagine Venice in 2125— confronting the city’s future through data modeling, atmospheric engineering, and symbolic rebirth.

CR We start with climate and population—two defining forces for architecture. Then we move through Natural, Artificial, and Collective Intelligence. Finally, we end with Out, which explores outer space—not as a place to escape to, but as a testing ground for ideas we can bring back to Earth.

Martin Rees, the UK’s Astronomer Royal, writes beautifully about this in the catalog: there’s no Planet B. That said, we’ve designed the Arsenale experience as a fluid journey—like walking through a living organism.

The boundaries between intelligences are porous, as they are in the real world.

DS What’s the riskiest or most provocative element of the Biennale?

CR Controversy is welcome— it sparks dialogue. The real risk is disengagement. If people don’t engage with the design, the network, the multiplicity of perspectives, then we’ve missed the point. We worked

with Sub, a Berlin-based studio known for designing experiences that resonate beyond architecture’s traditional audience. The challenge is to provoke participation.

GL Where should the Biennale go next?

Lesley Lokko’s 2023 edition emphasized the unbuilt and the marginalized. Your edition is about adaptation and systems.

What remains unexplored?

CR I return to Buckminster Fuller: utopia or oblivion. If we stay focused on form or minor aesthetic concerns, we’re headed for irrelevance. But if architecture becomes a tool for planetary transformation—socially and ecologically—then it moves to the center. That’s not just the next theme for the Biennale. That could be the purpose of architecture itself in the 21st century.

The 19th Venice International Architecture Biennale, which runs until November 23, is reviewed overleaf.

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DISPATCH

The Venice Architecture Biennale’s Arsenale delivers a dark, overheated vision of collapse, writes Daniel Safarik, while the national pavilions offer quieter models of repair, resistance, and renewal, reports Beatrice Galilee (overleaf).

The thing that hits you first when you enter the Arsenale’s Corderie is the darkness, heat, and humidity. You stumble into other disoriented attendees, trying to make out boundaries in the murk. Several tubs filled to the brim with seemingly brackish water ring the space, while the business ends of numerous suspended air conditioners —the part that faces outdoors— blasting heat into the room.

This is “Terms and Conditions,” the first exhibit in the stuffed-to-thegills International Exhibition of the 19th Architecture Biennale in Venice, curated by Carlo Ratti. Created by the engineering firm Transsolar with Bilge Kolbas, Daniel Barber, and Sonia Seneviratne, the discomfort is deliberate—it is meant to mimic the potential climate of Venice in 2100, at an average temperature of 42°C, compared to the comfortable 32°C outside and the standard conditioned indoor comfort level of 28.6°C, mercifully available just past a heavy drop curtain.

This immersive, borderlineinvoluntary set piece is there to ask us, as we blithely adjust our thermostats: 20

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“What have we signed up for? Did we remember to read the fine print?”

The same could be asked by Biennale attendees in general. Once released from the unsubtle, if necessary, messaging of the first room, one is then—pushed? drawn? rendered? processed?—to the end of the 317-m-long building, and then onwards through several more docklands structures, containing all manner of installations, flashing lights, soundscapes, bricks, and bric-a-brac.

Oh, and robots? Affirmative.

What did we see along the way?

What *didn’t* we see? Ratti’s open call netted some 750 participants staging more than 300 exhibitions in a smaller-than-usual amount of space.

The effect is of total sensory overload, like a graduate seminar stuffed into a 90-second theme-park ride.

The exhibition is organized into three parts, representing the three sub-themes of Intelligens: Natural, Artificial, and Collective.

The first focuses heavily on materials, particularly those that can be translated into viable construction with a lower carbon footprint than the standard operating procedures of today.

Crystalized carbon, recycled rope, mass timber, plants made of code, or making code, bricks made of elephant dung— every conceivable biomaterial has its day. But why haven’t their days come yet? The overall feeling is that we’ve seen all this before, in some cases, decades ago. The heavily vegetated ACROS Fukuoka Prefectural International Hall by Emilio Ambasz & Associates was completed in 1995.

And while it deserves credit for its net addition of greenery to the urban landscape (and for being one the few pieces of built architecture in the exhibition)—is this truly the state of the art in 2025?

Considering the scale and bombast of the exhibition overall, the proposed interventions seem oddly tentative and

BIG

Left— “Ancient Future: Bridging Bhutan’s Tradition and Innovation,” pairs a robot with traditional craftsmen carving a frame for the new Gelephu Airport.

meager in scope. Where are the proposals for the supply chains that will make any of these well-intentioned ideas practicable to implement?

“Artificial” is where the unavoidable question of artificial intelligence’s effect on the future built environment is presented. Although there are some stagings of uncanny verisimilitude involving humanoid robots, and immense graphic works with ominous, dystopic undertones, such as Kate Crawford and Vladan Joler’s “Calculating Empires: A Genealogy of Technology and Power Since 1500,” the overall mood is surprisingly reassuring. Not that it has much to do with architecture, but that drum-playing robot is no match for its human rivals. Other pieces suggest that AI can be used to generate desirable social outcomes, such as culturallysensitive, appropriately designed hospitals in sub-Saharan Africa.

Further along in “Collective,” the relative hierarchy of robotic technology and pre-industrial craftsmanship are firmly stated in “Ancient Future: Bridging Bhutan’s Tradition and Innovation,” by Bjarke

Ingels Group, Laurian Ghinitoiu, and Arata Mori. On display were live human woodworkers, deftly carving an elaborate pattern onto a timber frame, with an ABB single-arm robot quietly brushing up behind them.

This tableau is in theory repeated in BIG’s real-life project, the Gelephu Mindfulness City and its airport “Forest Terminal.” The message is clear: “Robotics doesn’t replace craftsmanship.” The relief is palpable.

“Data Clouds” by MIT’s Senseable City Lab suggests that studying the favelas of Rio de Janeiro with LiDAR, and using blockchain to formulate property titles and mitigate risks can represent a happy harmony between informal and information architecture.

But not much is said about the energy required to perform blockchain calculations, and how the carbon

footprint of that energy generation contributes to the further immiseration of favela dwellers.

In retrospect, with the frisson of vernissage behind us, and the hefty exhibition catalog in hand, there is a discernable, linear narrative that feels more coherent than the cacophony one confronts in the flesh. The message seems to be that it will take the collective effort of humanity and the full brunt of its technological arsenal to resolve the climatic crisis created by the industrial revolution, and no solution should be discounted, no matter how small, dated, clichéd, or seemingly irrelevant.

Ironically or not, this “throw everything at the wall and see what sticks” approach, the most intensive act of curation in the whole exhibition seems to have been performed by AI. The ponderous architectural jargon on the placards rendered in 8-point type is helpfully summarized by AI into one or two sentences, easing the strain on the overstimulated receptors of visitors, blinking their way through the hot, dark, noise.

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This year’s edition of the Venice Architecture Biennale unfolds in two somewhat reduced movements: on one hand the curated exhibition led this year by MIT’s technooptimist Carlo Ratti took place in only one of the traditional two venues (the Central Pavilion being closed for renovations, leaving the Arsenale to be turned into a sort of three dimensional representation of 700 of Ratti’s open browser tabs), and on the other hand the constellation of singular national pavilions in the Giardini were muted by further closures, including the Czech and French pavilions, as well as the still-at-war Russian and Israeli outposts.

These absences were mitigated by some strong new pavilion additions, including Qatar, Togo, Oman, and Azerbaijan, which were scattered across the Arsenale spaces and the city’s archipelago. The top five pavilions each offer intelligence by thoughtfully contributing to a field of knowledge in different but purposeful ways: some new canons, new books, a certain pragmatism. There’s little here by way of utopias or even hopeful solutions, which, given the shared precarity we face, is a type of intelligence that is warmly appreciated.

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Below— Every element in the Danish Pavilion exhibition was from the building’s own reconstruction.

There was a cleverness in the Danish Pavilion’s choice to exhibit its own renovation that, in the wrong hands, could have been cynical, but instead became a joyful nerd-out of architectural detailing, craft and materials.

Curator Søren Pihlmann’s Build of Site follows in real-time the restoration of the pavilion itself, as familiar walls of the low brick and stone structure are stripped to their structural bones and new materials are assembled before the visitor’s eyes. There are no glossy panels or pristine maquettes—just scaffolding, joints, and a quietly choreographed ecosystem of reuse. Every element is sourced from the building itself or nearby waste streams. Bio-based binders, exposed insulation, salvaged panels: each detail signals a deep commitment to circular construction, but without aestheticizing roughness for its own sake. The exhibition

Qatar All eyes were on Qatar as it made its national debut in Venice. Beyti Beytak made an ambitious and also delicately balanced offering that unfolded in two parts: a temporary pavilion and a full-scale exhibition.

The temporary pavilion, constructed in the Giardini by

HAMPUS BERNDTSON

Denmark

is neither performance art nor greenwashing, it simply shares the realities of material legacies and architectural afterlives.

Pihlmann deftly presents a counterpoint to much of the speculative, interdisciplinary and ultimately more worldly narratives that architects often speak to in Venice by inviting the audience to truly value, observe and appreciate what exactly it is that makes good buildings work.

Exhibition name: Build of Site.

Curator: Søren Pihlmann.

Location: Giardini della Biennale

GIUSEPPE MIOTTO / MARCO CAPPELLETTI STUDIO

Pakistan’s pioneering humanitarian architect Yasmeen Lari, was a bamboo-framed structure designed as a space of welcome and ecological consciousness.

It occupies the site where Qatar’s permanent national pavilion —designed by Lina Ghotmeh— will open in two years.

Meanwhile, in the Palazzo Franchetti, curators Sean Anderson and Aurélien Lemonier orchestrated a precise and generous exhibition spotlighting architectural practices across the Middle East, North Africa, and South Asia. Among the contributors were Salima Naji, whose work in Morocco revives and reimagines vernacular earthen traditions; Lebanese architect Wael Al Awar, known for his climate-responsive material innovations; Bangladesh’s leading

light Marina Tabassum, and the late, great Geoffrey Bawa, a foundational voice in Sri Lanka’s tropical modernism.

These projects, spanning generations and geographies, resisted national essentialism in favor of shared, cross-cultural narratives of place and care.

The exhibition comes hot on the heels of some interesting new architectural commissions in Qatar, notably Elizabeth Diller’s women-only mosque, Herzog & de Meuron’s Lusail museum, and Alejandro Aravena’s Art Mill.

Interested to see what comes next.

Exhibition name: Beyti Beytak.

My Home is Your Home. La mia casa è la tua casa Curators: Aurélien Lemonier and Sean Anderson. Location: Giardini della Biennale & Palazzo Franchetti.

Mexico

Above— Qatar’s pavilion was a temporary bamboo-framed structure in place of its future building.

Mexico’s pavilion offers an unexpected parallel between the canals of Venice and the ancient chinampas of Lake Texcoco—agricultural plots built over water through intricate layers of mud, sediment, and vegetation.

Chinampa Veneta doesn’t just reference this Mesoamerican system—it reanimates it, proposing it as a living architectural model for a world in ecological crisis.

The exhibition ponders what could be learned from Xochimilco, a UNESCO-designated waterworld, as it grapples with the same precarity as Venice itself—rising water, shrinking land, the politics of purification and survival. The Vertical Urbanism 4 II / 2025 AGENDA

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Below— Mexico’s pavilion drew parallels between the Xochimilco water-world in that country and Venice itself.

& Ana Paula de Alba, Estudio María Marín de Buen, ILWT, Locus, Lucio Usobiaga Hegewisch & Nathalia Muguet, Pedro&Juana Location: Corderie dell’Arsenale

Togo Togo’s first-ever pavilion at the Venice Architecture Biennale presents a compelling, timespanning portrait of West African architecture. Titled Considering Togo’s Architectural Heritage and curated by Studio NEiDA, the exhibition traces a rich continuum—from the ancient Nôk caves and the sculptural Tatas Tamberma in the north, to the ornate Afro-Brazilian villas built by freed slaves in the south, and the modernist landmarks of mid-20th century Lomé. Each layer reveals

how architecture in Togo has evolved in response to climate, migration, and colonial influence.

The pavilion emphasizes not only what was built, but how and why. Urban expansion in Lomé— particularly after independence in 1960—ushered in foreign styles and materials that often overshadowed local building techniques. While icons like Hôtel Sarakawa remain active, others, like Hôtel de la Paix, stand as fragile reminders of a city in transition.

Rather than treat heritage as static, the pavilion frames it as dynamic—inviting reflection on how architectural knowledge can be conserved through transformation.

Conservation here is not about stasis, but adaptation. Through immersive storytelling and careful curation, Togo’s pavilion positions architecture as both legacy and method—one that is deeply contextual, materially intelligent,

CHINAMPA VENETA

installation unfolds with the slow logic of growth. Visitors move through chinampas at various stages of growth, from the dense, seed-filled chapines—small cubes of nutrient-rich mud—to a fully planted agroforestry landscape.

Vines climb native trees in the vite maritata tradition, while corn, beans, and squash rise in Mesoamerican polyculture.

Curated by a multidisciplinary collective of some of Mexico’s most interesting architecture studios, Chinampa Veneta dissolves the divide between cultivation and construction. It treats architecture not as object but as ecosystem— regenerative, participatory, and deeply informed by ancestral intelligence. In doing so, it invites a reconsideration of how we inhabit the planet, proposing that design might grow, heal, and collaborate rather than simply build.

Exhibition name: Chinampa Veneta Curators: Estudio Ignacio Urquiza

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WODY YAWO

Above— Togo’s pavilion posed colonial architecture as worthy of conserving and investigating.

Catalonia A little further out, over a few perfectly proportioned canal bridges and around several winding roads, the Catalan Pavilion makes the top five, if only for its commitment to the bit: a water pavilion that is pure theater—bright blue carpets, wobbly walls, weird lighting and a fearless curatorial perspective, one that only Eva Franch i Gilabert could marshal.

Above right— Catalan Water Parliaments, curated by Eva Franch i Gilabert.

ARAUNA+PARATEXT

WODY YAWO

and essential to imagining more just, sustainable futures.

Exhibition name: Considering Togo’s Architectural Heritage Curators: Studio NEiDA (Jeanne Autran-Edorh and Fabiola Büchele).

Location: Squero Castello

Built inside a repurposed naval warehouse, the pavilion brings together Future Labs held across Catalonia and the Balearics, an Atlas of speculative water imaginaries from around the world, and 100 Words for Water, a conceptual lexicon shaped by artists, scientists, and activists.

All of it was as refreshing and playful as it was kind of provocative and fascinating.

At its center, Water Parliaments explores the architecture of water governance across seven case studies, from droughtafflicted landscapes to submerged cities. Visitors walk through a theatrical environment of shifting humidity, steam bursts, filtered light, and sound—an immersive

microclimate that demands attunement rather than explanation. The installation is not didactic, but experiential: the kind of space where you feel a thesis before understanding it.

It resists the sterile metrics of sustainability, and instead offers a poetic, speculative approach to planetary crises.

If architecture is to grapple with ecological collapse, the pavilion argues, it must do so not only with technical solutions but also with rituals of care, collective memory, and slow negotiation.

Exhibition name: Water Parliaments Curators: Eva Franch i Gilabert, Mireia Luzárraga, Álex Muñoz Location: Cantieri Cucchini, San Pietro di Castello Vertical Urbanism 4 II / 2025 AGENDA

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ANDY RYAN

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DESIGN

The architect Steven Holl has long been a progenitor of radical experiments in vertical urbanism. With Simmons Hall—his dormitory for MIT—recently branded “the ugliest building in America,” the 77-year-old architect shares reflections with Will Hunter on a career defiantly pushing boundaries—from Zaha to Viñoly, Berlin to Beijing.

This discussion has been edited for concision and clarity.

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Will Hunter The news hook for our talking is that the Sweden-based group Architectural Uprising recently named Simmons Hall at MIT the “Ugliest Building in America.”

I’m curious how you think about the subjective nature of beauty and ugliness—and how form gets discussed. What’s your approach to beauty?

Steven Holl You read my response to the students, right?

When it was first posted, I just said, “Thank you for the beautiful pictures.”

It’s a great building. The people who live in it love it.

We were just in Boston a few months ago—I took my nineyear-old daughter and five-year-old son, and we explored the whole thing. It’s in great shape, even after twenty years.

This kind of classical pushback is nothing new. It was going on in the 1980s with Léon Krier leading the charge—this idea that classical architecture is somehow better than modern. It’s a recurring story. There’s always tension there. The political right has always gravitated toward classicism—Hitler, Stalin—it goes way back. So I’m not surprised. In fact, I take it as a badge.

We’re more modern. More radical.

I actually ran into Nicholas de Monchaux, the head of MIT Architecture, last night on the High Line—he gave a speech at Rick Scofidio’s memorial. And he loves the building.

So do the students who live in it. It’s not a bad thing to have attention on a building that’s held up this well. Anyone who visits will see that for themselves.

Someone calls it the “ugliest,” and suddenly people are looking again—reconsidering. Fine by me. As they say, there’s no such thing as bad publicity. It makes people think.

Above— Watercolor by Steven Holl showing the interior voids of Simmons Hall, with doubleand triple-height openings that channel light and create shared spaces.

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WH It struck me as a good moment to reflect on Simmons again. I was a Fellow at MIT a couple of years ago and tried to move into one of the Fellows’ apartments. I wasn’t accepted— but I bear no grudge! I really liked it. I thought it had a lot of integrity. It looked like you could live quite stylishly there.

SH How long were you at MIT? WH Nine months.

SH Oh, only nine months!

WH Yeah—I’d done a year at Harvard before that, then MIT, then moved to New York. I found Boston a bit too remote.

SH I found it remote, too. I’m very glad to have realized a building there, but years ago I was invited to take a tenured position at the GSD—Rafael Moneo extended the offer. Gerald McCue was the dean. I gave a lecture they liked, so they arranged a meeting with the president, Derek Bok. It was meant to be 10 minutes—but I came back an hour later. They asked, “Why did he keep you so long?” I said, “We started talking about his childhood in Los Angeles—he grew up in a Schindler building.”

WH How nice!

SH And Moneo and Gerald didn’t even know that. Anyway, the next morning, after my lecture, they offered me tenure.

They proposed moving my office from New York to Boston and

doubling my Columbia salary. So I went to [James] Polshek at Columbia and said, “Listen, I have to take this offer. It’s tenure track, double the salary, they’ll move my office—everything.”

I told him, “I don’t want to leave New York, but I don’t have a choice. I only have a few small projects.” And Polshek said, “Wait a minute—we’ll get you tenure here.” And he did. That’s how I got tenure at Columbia.

TAEHYUNG PARK / PCF&P

WH Harvard was a good bargaining chip. I think it’d be hard to move an architecture office from New York to Boston.

Above— One Dalton, Boston, designed by Henry Cobb as his final building in the city. A mixed-use tower of glass, it rises behind I. M. Pei’s water garden and thin concrete slab tower.

SH I like Boston for many reasons. We just took our kids up there and stayed at One Dalton—Henry Cobb’s last building.

It’s a condo and hotel tower. It’s glass, but it’s thoughtful—pure Henry Cobb. At the top, there’s a presidential suite or two. When we arrived, I said to the concierge, “I knew the architect quite well,” and told some stories. They said, “Wait a minute,” and gave us the presidential suite for the price of a regular room.

My kids were like, “Wow—look at this!”

WH What I find interesting is that, despite the big universities, the city doesn’t have much “vibe.” It goes suburban fast. Even around Harvard and MIT, the housing morphology is pretty suburban. It doesn’t feel like it supports urban life.

SH But there are places that are very interesting—like the Science Institute by I. M. Pei. He did that water garden and a thin concrete slab of a tower you can see through. The sunlight shines through it because it’s so shallow. And the water garden is still there. One Dalton sits right behind it, so we could watch the

Above— Final sectional drawing of Simmons Hall, showing the evolution from early conceptual studies to the realized design.

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Above— MIT campus master plan in watercolor.

Developed as an alternative to a local firm’s brick-wall scheme.

Right— View of Simmons Hall across the snowy playing field at MIT.

sunrise through Pei’s original flat tower. There’s Trinity Church, the Back Bay—there’s a lot to see in Boston.

SH That was the whole idea—the hollowing out inside a rigorous exoskeletal frame. The voids are the social spaces— double- and triple-height openings. I was fighting for the social life of the building.

When we were hired, there was a local Boston firm’s brickwall master plan in place. I told MIT Chancellor Larry Bacow, “I’d love to do the project—but not with that master plan. Can I make a new one?” He said, “What do you mean?” I said, “Let me sketch something and show you tomorrow.” I proposed an idea: instead of a wall, there’d be porosity. The playing field would stay, but instead of enclosing it, the architecture would open it up.

He asked, “How long do you need?” I said, “Six weeks—and $150,000,” or whatever the figure was. And he said, “Okay, you’ve got it.” So I had time to do the master plan. I developed four buildings, each with different types of porosity. When I returned to present them, Bacow asked, “Which one would you like to develop?” I said, “The folded street.”

It rose 120 ft (36.5 m)—a continuous ramp of dormitory rooms lining a street-like spine. You could walk up the entire 30

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ANDY RYAN

WH I suppose I’m thinking about living there, about how people meet in an urban way—which brings me back to Simmons Hall. There are thousands of interesting people working across disciplines, but how do you bring them together? How did you think about the building’s social life? What was the social organism you were trying to create?

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ANDY RYAN

Above— Simmons Hall: anodized aluminum reveals structural stress patterns in the exoskeleton, turning engineering information into architectural expression.

building. The social space was the street. But then, as we moved into schematics, they came back and said, “We’ve just discovered a 100-ft height limit. You can’t do this building.”

It wouldn’t work at a lower height. They said, “Choose one of the other porosities. We still need the design by 12 September—and now it’s 1 July. We have to start over.”

WH I read there were three schemes: one with towers, one more like an Italian hill town, and then the sponge—the final one. Is that right?

SH Right. But I only developed two. The folded street was the first, but around July 1 they said, “That won’t go. You’ve only got two months.” So I told the office, “If we agree to deliver this by 12 September, we’ll have to work all summer—no vacations, weekends included.” I said, “Let’s take a vote. Are we in or out?”

We voted—and I was the only one who said no. But everyone else was in, so we did it. Seven days a week, all summer. That’s how we developed the sponge—this idea of overall porosity. Guy Nordenson helped with the structure, which is very advanced: an exoskeletal frame that carries the entire load. There are nine windows in every room, and they’re also integral to the structure.

So for MIT, it’s sophisticated—technology is visible.

And then there’s the story about the color. I’d planned to assign each of the ten student “houses” a different color—using the depth of the exoskeleton to set the sill, jamb, and head of each window in colored aluminum. You’d stand on the playing field and see exactly where your house was. But in a meeting, the students and staff said, “We don’t want to be identified from the

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Right— Interior view of Simmons Hall, featuring the curving central staircase.

Set within the building’s porous core, it connects shared spaces and reinforces the emphasis on circulation as social infrastructure.

ANDY RYAN

Below— Interior view of Simmons Hall: the exoskeletal fenestration casts a chiaroscuro play of light and shadow.

outside.” What was I going to do? I still needed the color. I flew back to New York. On my desk was Guy Nordenson’s engineering diagram—his stress map of the exoskeleton. And you could read the structural forces through the color: red was a number four, blue was a number two. You could literally see the load paths in color. I thought, “That’s perfect for MIT.” The color system became a reading of the structure. I still love that idea.

WH That’s an even richer solution. It’s good the students pushed back—it ended up better.

WH Were there any other big battles you remember?

Any compromises you regret?

SH You know, Bill Mitchell was a great supporter. I really loved him. A huge figure in architectural culture. He had the

PAUL WARCHOL

SH Another thing we fought for was the cafeteria.

McGregor—the dorm built before ours—only had vending machines and communal kitchens, which never work. Every sink had dirty dishes and pots of beans no one cleaned up.

I said, “You can’t do that again. You need a cafeteria— it’s a social space. People meet there.” And if we put it on the “street”—the main circulation—it becomes a gathering point.

That was a big fight, and I won. And I’m really glad I did.

The kitchen is still in use. It’s appreciated. There’s even a barbecue area out back. That was a battle we won. The social life of the building was very important to me. That part wasn’t neglected at all. I fought for it all the way down the line.

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Below— Structural analysis drawing by engineer Guy Nordenson and Associates, mapping stress across the exoskeletal frame.

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Right— Top-lit social void within Simmons Hall, defined by curving walls and sculpted light.

ANDY RYAN

ear of the administration—Chuck Vest, Larry Bacow.

There’s a book called Redefining MIT that includes Frank Gehry’s building, the Media Lab, and the other projects from that period.

They wanted to make MIT relevant again—to architectural culture. Like it had been when Eero Saarinen did the chapel.

And they had support at the top. Bill Mitchell really made that happen. He was such a force—bless his soul. That’s why we were selected, along with Larry Bacow.

Charles Vest was one of the great university presidents—just fantastic. Without his leadership, that whole wave of architecture at MIT wouldn’t have happened. We were part of that. So in a way, I was in “the right place, at the right time, with the right idea”—as Walter De Maria used to say. I never forgot that line.

At the time, I was also working in China. We did Linked Hybrid in Beijing and the Horizontal Skyscraper in Shenzhen.

But now, China is dead. I still have three or four people there because of two unfinished projects, but otherwise, it’s over.

Now I’m working in Tirana, Albania. The Prime Minister, Edi Rama, is an artist—a fantastic guy. I just came back from his “Bread and Salt” architecture festival. There were a hundred architects there. It was a big event around all the work happening there. It’s a very interesting moment. You should go—do a report.

WH Looking back on Simmons, were there any lessons that informed later projects? Things that worked well—or didn’t?

Below, left— Simmons dining hall, set along the building’s central circulation spine.

Below right— Dormitory room in Simmons Hall.

Steven Holl designed all the furniture.

ANDY RYAN

PAUL WARCHOL

SH The exoskeletal frame, for sure. That—and the idea of lowering the window-to-wall ratio—definitely carried into Linked Hybrid in Beijing. That’s eight towers, all with

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SHU HE

Right, above— Size comparison with the Empire State Building.

Right, below— Horizontal Skyscraper: the lifted form preserves green space below, integrating architecture and ecology into a continuous urban field.

STEVEN HOLL ARCHITECTS

Above— The Horizontal Skyscraper in Shenzhen, China,

by Steven Holl Architects.

The elevated structure bridges across a landscaped park, continuing Holl’s exploration of porosity, structure, and urban connectivity at a vastly different scale.

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SHU HE

exoskeletal frames. The windows there are larger and the frame heavier, but the principle came from Simmons: structure on the outside, no interior columns.

It probably started at MIT and moved forward. We took it further in Chengdu, where the exoskeleton is stained white—a penetrating stain. That tower reached 35 stories. We were pushing the limit of exoskeletal concrete construction. Quite tall.

I remember presenting the Chengdu project in Singapore to the client, Mr. Liu. Rafael Viñoly was also there, presenting another scheme. He really liked ours. I’m pretty sure his Park Avenue tower was influenced by our Chengdu frame. He took it far—maybe too far. Now they’ve had problems: elevator issues, building sway. I think it’s the slenderness ratio—he was pushing it. But we don’t know for sure. There are a lot of variables. I follow it closely. Rafael was a friend.

Last time I saw him was at a Wang Lu concert at Carnegie Hall—absolutely fantastic pianist. During intermission, I asked him, “Did you take the exoskeleton idea from me, Rafael?” He pulled down one of his many pairs of glasses—you know, he always had two here and one there—and said, “It’s a great concert, isn’t it?” And that was that.

I knew him from when he first came to New York. I arrived in ’77. I think he came from South America around the same time—though he already had an office there. He bought an apartment on Park Avenue. I lived on a plywood shelf in a cold-water loft in an abandoned department store. We had very different lives—but we arrived at the same time, so we were friends. I remember visiting his studio on the second floor of one of the few Louis Sullivan buildings in New York. He was working 38

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on the Tokyo Forum competition—that giant glass boat.

Winning it was his breakthrough. His office exploded after that.

WH And what would you say was your own breakthrough?

SH Kiasma—the museum in Helsinki. I had an office of four people. In fact, when we won it, we were down to just two or three. There were 416 entries. That was 1993. It opened in 1998.

A big success. Still in great shape—we visited last year, and it’s beautifully restored.

WH So Simmons came quite soon after? Within a year or so?

SH We opened Kiasma in ’98, and got the Simmons commission in ’99.

WH That must’ve been the moment your practice scaled up?

SH Yes, it grew to seventy-five people—which I hated. I don’t like managing that many. Around 2008, we hit seventy-five. The strange thing was, we were still growing—but I didn’t want to.

I had three projects under construction in China, so even while firms in New York were laying people off, I was hiring. It was crazy—didn’t make much sense. And then, of course, China just stopped. Now it’s dead. But who knows—it might come back.

WH And realizing you didn’t want to manage 75 people—how did you begin thinking about the next generation leading the practice? How do you see things evolving?

SH I think architecture is an endangered species. It’s become very commercial. The value system is off. Last night, I was talking about the only questions that really matter: why we build, what we build, and how we build. That’s why I keep teaching at Columbia—to keep those questions alive.

But I do think we’re losing that. Everyone’s focused on scaling up, pumping out buildings. Out here [gestures out the window of his New York studio], there’s a row of skyscrapers— probably designed in two weeks on a computer. And there they are: big glass nothings.

I won’t name names, but there are three in a row—terrible buildings. They throw the street into shadow. No public space, no light at the base. Just a silly zigzag going up—a diagram pretending to be an idea. All glass. Gigantic. Monocultural.

Un-urban. That’s not the future of architecture. I hope young architects find more soulful ways to think and build. That’s why I’m still teaching.

WH Are there younger practices you’re excited about?

SH Of course. It’s unpredictable, but I really like nARCHITECTS—Eric Bunge and Mimi Hoang. Mimi used to work for me. She was part of the team for the Nelson-Atkins competition.

There are also some great young firms in Portugal, clearly drawing from Álvaro Siza. It’s amazing—Siza is still working.

He’s 94 and still drawing. At the Tirana architecture conference in Albania, he couldn’t come in person but sent a video. He spoke about how much he admires Edi Rama—the Prime

WIKIMEDIA

Left— Sliced Porosity Block in Chengdu, China. The complex carves sunlight and air through its mass via deep voids.

Left— 432 Park Avenue in Manhattan, designed by Rafael Viñoly. Holl believes he inspired the tower’s exoskeleton.

Minister, who’s also an artist. Right after, I think it was Camilo Rebelo—another Portuguese architect who collaborates with Siza—who came up to me and gave me books on their work.

There’s this tradition in Portugal of beginning with a concept sketch. That kind of care and detail, like Scarpa.

It’s encouraging.

And as I said, you should go to Albania. Tirana is where it’s happening. Edi Rama is commissioning a lot of young architects.

At the big festival dinner—500 architects at the King’s Castle— Kengo Kuma and I were seated at his table. Rama stood up and said, “I want everyone to toast someone else.” And then he said, “I’ll start. I’m toasting Kengo Kuma and Steven Holl.”

And I thought—okay, I’m getting old! We were the oldest ones there. But the energy was with the young people. If you want to know where the next generation is, go to Tirana. Rama is giving them work. It’s a very optimistic place right now.

WH I think that’s true across Europe. There are some very compelling younger practices. Just yesterday, at NYU, I hosted some of the architects behind King’s Cross. The level of thought was extraordinary. Even something like Niall McLaughlin’s power station with mixed-uses is so crafted. The quality, the care.

SH Yeah. But let’s not dismiss LA entirely—there’s still great work happening. Michael Maltzan is doing some of the best social housing in the country. Are you familiar with his work?

WH Yes. In fact, I asked Niall McLaughlin to review Maltzan’s housing back in 2013, when I was at The Architectural Review.

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SH He’s particularly good. Same with Neil Denari. There’s real thought and care in what they do.

WH Do you see them as part of a broader culture in Los Angeles, or do they stand out as exceptions?

SH There’s definitely a culture. LA has always been a kind of hothouse for invention.

WH In terms of built work though—not just education, like SCI-Arc. Does that inventiveness translate into the architecture itself ?

When you were at the AA, was Zaha there too?

SH Yes—we discovered Zaha. She was a close friend for life.

I have the last photographs of her—she came to our apartment in New York to give my newborn daughter a yellow Issey Miyake dress. That was 16 March. She went to Miami shortly after and died of a heart attack on the 31st.

We met in 1976 at the AA. Elias Zenghelis gave this brilliant assignment: instead of assigning a site and a program and asking for a form, he gave the students a form—Malevich’s Architecton— and told them to invent the site and the program.

Zaha turned it into a complex bridge. I remember sitting with Rem on one side, Peter Cook on the other—we all leaned forward and said, “This is brilliant.”

We were witnessing her emergence. She had just come from Léon Krier’s unit—he’d apparently drawn arches on her project in pink magic marker. We told her, “Take that off—this is brilliant.”

And over the years she’d say, “Oh, that’s not a true story.”

WH

She probably said she discovered you.

SH [Laughs] Probably. We were friends forever. Every time I beat her in a competition, she’d send me a Stevie Wonder 40

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MICHAEL MALTZAN

WH

STEVEN HOLL ARCHITECTS

SH Over the years, yes. Denari, Maltzan, Thom Mayne, Eric Owen Moss—they’ve all pushed things forward. There’s been consistent experimentation.

And I have a story. I was very close with Rem Koolhaas— we met at the AA in London. I didn’t graduate, but I was there in 1976. Rem, Elias Zenghelis, and I became great friends.

Around 1987 or so, I had two commissions for houses in Los Angeles. Whenever Rem came to New York, he’d call me up and say, “Let’s have dinner.” So one evening I told him, “Rem, I’m thinking about moving back to California to do these houses.

All I can get in New York are apartments.” I was born on the West Coast—first registered in California. I’d lived in San Francisco for five years. It seemed like a natural move.

And Rem said, “I wouldn’t do that if I were you. You’ll just be one of them.”

I never forgot it. And I never moved. He was right.

The very next year, I won the Gedenkbibliothek competition in Berlin—1988, the bridge over the original building. Then came a project in Venice. It was much easier to work from New York to Europe than from Los Angeles.

That was one of the reasons my practice ended up more European, and international. My first major built project was in Fukuoka, Japan—thanks to Isozaki.

Above— Housing by Michael Maltzan Architecture in Los Angeles. Holl praises Maltzan as doing “some of the best social housing in the country.”

Top— Steven Holl iterates designs through models, such as this unbuilt competition entry for the Palazzo del Cinema in Venice, 1990.

congratulations—she called me Stevie Wonder. And when she won, I’d send her one too.

WH And do you still compete with the office now that Patrik is leading it?

SH No. It’s not Zaha anymore. They’ve tried to brand it— to make it a style. As Elias Zenghelis said, “I can’t even look at the work.” It’s not the same. It’s something else entirely.

WH Do you think that’s about process? Her early work was hand-drawn, developed through layering on tracing paper. Did it lose something when it became fully parametric and digital?

STEVEN HOLL ARCHITECTS

SH All I know is her mind. She was truly brilliant—an inventive, original thinker. And she wouldn’t have launched like a rocket ship without Patrik’s technological support.

Together, they were unbeatable.

I think Patrik joined her around the time of the Vitra Fire Station. I was at the opening—June 1993. I’ve got photos of me, Zaha, Philip Johnson, Rolf Fehlbaum. It was a real moment.

She designed every detail of that building. It was fantastic.

She was the real deal. But even near the end, she told me, “I don’t like this big office. I’d like to take five people, go away, and just do my projects.”

She hated being forced to travel constantly—for groundbreakings, for openings—especially for things she wasn’t fully invested in. That wore her down.

WH In your own practice—your relationship between architecture and art, and the way you draw and paint—how does that interface with the studio? How do others contribute creatively?

How does the architecture move forward?

SH I draw on these little five-by-seven watercolor pads.

I photograph the sketches and send them around. Once the iPhone came out, it was perfect—the format just worked.

This morning, for instance, I drew a light fixture at 6:00 a.m., took a photo, and sent it to two people.

There’ll be a model by tomorrow. It’s a constant interface —very fluid. These are concept sketches, and they move quickly through the office.

WH

And then it goes back and forth?

SH Usually we move to models. Then the design evolves —either I make another sketch, or we revise the model. We have a model archive which chronologically holds all the models of designs since 1978. Many inspiring creations were never realized, such as our competition entry for the Palazzo de Cinema (Venice, 1990). However, the idea is clear, which is what really matters—architecture does not have to be built to have meaning Steven Holl writes about what informs his work in VU’s Inspiration feature on page 146. Overleaf, current MIT students reflect on life inside Simmons Hall—recently branded the “ugliest building in America.” And on page 11, the late Léon Krier offers his final reflections on tradition and democracy in architecture.

Left— Linked Hybrid in Beijing: a mixed-use complex with eight towers connected by skybridges, creating a network of public spaces.

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Vertical Urbanism explores the beginnings of MIT’s Simmons Hall in 1999—and chats with current students to find out what they think.

When Sweden-based advocacy group Architectural Uprising unveiled its inaugural “Aesthetic Atrocity Awards” earlier this year, one name topped the list: Simmons Hall, the famously porous dormitory at MIT designed by Steven Holl Architects. Citing its “classic hallmarks of Modernism and its failures,” the group— whose mission is to oppose contemporary architecture in favor of traditional design—lambasted the 2002 building as “colossal, impractical, and unwelcoming.”

Holl’s response? “Thank you for the beautiful photos.” He added that the students “were very happy and futurefocused in the spirit of MIT,” and accused the group of aligning with “[the United States’] barbarian president.”

This spat between designer and campaigners provided the perfect opening to revisit the project in more depth—to explore how much the social organism of a unique MIT dorm drove its design, and what it’s actually like to live there now.

Beginnings of Simmons In 1999, MIT set out to build a dorm that would embody its new educational mission. A recent task force on student life and learning had redefined the university’s

Right— Simmons Hall floor plans, levels 1 (below) and 2 (above).

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priorities, arguing that education happened not just in labs and lecture halls, but in the informal spaces between them—in conversations over dinner, late-night problem-solving in lounges, or friendships forged across disciplines. The new residence, known initially as “Residence 2001,” was intended to support that vision. It would be more than a building—it would be a prototype for a new kind of learning community.

To guide its development, MIT assembled a “Founders Group,” a cross-section of students, faculty, and staff charged with advising on both the physical design and the social culture of the building. Among them was Jeff Roberts, then an undergraduate, now Director of Zoning and Development for the City of Cambridge. His detailed account of the process—still available on the Simmons Hall website—offers a rare student-side view of how the project unfolded.

From the outset, Roberts writes, the group faced structural limitations. The program for the building—how much space would be devoted to dorm rooms, dining, study, and social areas—had already been determined by MIT’s

Planning Office and an external consultant. “Many of the innovations that people talk about with regards to Simmons Hall... were developed as part of this process long before the architects were ever involved.” The architect himself, Steven Holl, was already on board when the Founders Group began. Roberts recalls being told Holl was “a genius,” but also notes: “I had heard that Steven Holl didn’t have any experience in designing student housing and had designed very little housing at all.”

Holl’s early proposals were striking but impractical. The first scheme—nicknamed the “pencil towers”—featured four tall, skinny towers, each with a differentshaped floor plate. “After seeing this, many of us in the group had to strongly but politely explain to him what we had goals for the community that involved largescale interaction, and isolating people in high-rise towers really didn’t seem to accommodate that goal.”

The next concept fared better. Inspired

by Italian hill towns, it consisted of a long, winding corridor that gradually rose through the building, linking rooms and lounges into a continuous social surface.

“Despite the peculiarity of the design,

many of us in the group actually liked the Italian hillside concept quite a lot because it seemed to much better support our social goals.” But the City of Cambridge wouldn’t permit a building that tall, and the idea was scrapped.

The final design—the one built— emerged quickly. It became known as “the sponge” for its grid of punched windows and porous structure. “With the dorm still expected to be done by fall 2001—and it was now nearing fall 1999—there would not be time to develop another option.

Basically, we were getting the sponge whether we liked it or not. So overall, we chose to like it.”

The group remained hopeful. They supported the idea of large vertical voids to encourage cross-floor interaction. They saw promise in the open roof terraces. But one by one, those ambitions were trimmed by code and cost. “As the design progressed... the atria became smaller and smaller and more enclosed.” Fire regulations, Roberts writes, meant the lounges had to be sealed off. “Instead of serving as the main nodal points of the building, they became small, cavernous offshoots that we knew would not attract or encourage social interaction.”

The roof terraces were originally intended as shared outdoor spaces. But a recent student suicide had triggered new safety measures. MIT’s safety office insisted they be restricted or fenced off.

“The architects thought that a fence would look terrible, and decided to alter the layout so that all of the terraces were accessible only through housemaster, visiting scholar, or graduate apartments.”

Furniture became another sore point.

Holl insisted on designing every element, down to the perforated trash cans. Roberts campaigned hard for round dining tables, which he believed encouraged social mixing. “Dinner time was probably the most important and dependable element of my life at MIT,” he wrote. “I pressed on him the idea that a dining hall needed large tables... In the end, Holl’s original idea stood, and we got the furniture you have, tiny tables that mostly seat 4, and no more than 6.”

By the time construction was delayed—thanks to a lawsuit from a neighboring property owner—the Founders Group’s role was already evolving. “We didn’t make decisions,” Roberts writes. “We started conversations.”

They focused on recruiting students who

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Right— Simmons Hall floor plans, from bottom: levels 3, 4, 6 and 7.

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Right— Simmons Hall floor plans, levels 8 (below) and 9 (above).

would carry those conversations forward, pushing back on perceptions that Simmons would be an all-freshman dorm, or worse, an administrative experiment.

They proposed a “town hall” model of governance and insisted visiting scholars contribute to the community, not just occupy its best apartments.

The Founders Group sought to instill the idea of Simmons Hall as a social machine—and to defend the expectation that its community would govern itself.

“We had to create life from a sponge,” Roberts writes. “And while our mission was never entirely clear, our goal was certain—we had to get people to see Simmons Hall as a new living environment, a new community.”

Life at Simmons Today Vertical Urbanism approached the Simmons Hall student government and spoke with four current residents about their experiences of living in the building.

While these views are not necessarily representative of all 350 students who call Simmons home, they offer a snapshot of how Holl’s radical design plays out in daily life—two decades after its opening.

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When MIT first commissioned Simmons Hall, the goal was to create a building that would encourage chance encounters and social overlap. In practice, that idea has yielded mixed results. “You can get lost,” said Ian Frankel, a first-year student. “And like, it’s literally a 2D layout—it’s just three towers, right? You shouldn’t be able to get lost in this dorm.

And it’s possible to get lost in this dorm.”

That theme came up repeatedly: the sheer scale and spatial fragmentation of the building can make everyday interactions feel distant or effortful. “Why, when I want to see my friend, do I have to take two elevators to specific floors—not even all floors?” Frankel added.

Diego Temkin, who also lives in Simmons, was more blunt. “Simmons is, like, the worst socially engineered building I have seen. You stare down this, like, overly massive, empty hallway, which has like random concrete just jutting out... and you see no one.”

But Eugenie Cha, dorm co-president, pointed out that the spatial fragmentation has allowed micro-communities to form across the towers and floors. “Some towers offer more isolation and a tighter

community, especially on the higher floors in Tower A. Versus on the lower floors or on continuous floors. Culture is very different.”

Nearly all students commented on the building’s distinctive interior geometry— especially the curving walls and unusual room layouts. “The first two weeks you live in it, you’re like, ‘Oh my God, I live in an art installation. It’s so cool. I have curvy walls. It’s goofy. It’s weird,’ ” Ian said. “And then literally after two weeks you’re like, ‘I’m sick and tired of this. Why am I wasting space in my room because there’s a freaking curved wall, and I can’t put my desk against it?’”

That tension between visual drama and functional inconvenience was a recurring theme. “It wasn’t designed for humans,” Frankel said. “It was designed for being like an art installation first, that they happened to shove humans into.” Temkin echoed this. “It’s so obviously not designed for the people who live in it. It’s designed to be cool, like a cool building, but it’s not designed to be a nice place to live.”

And yet, despite its oddities, Simmons does have its strengths. “I will say it’s not the worst dorm to live in at MIT,” Frankel

admitted. “Because it has larger rooms on average than the rest.”

Perhaps more than in any other MIT dorm, the community inside Simmons has used the architecture as a surface for expression. “There’s a lot of space for murals to go up,” said Cha. “Each building area has their own unique murals.”

One tower has a map of the United States painted on the wall, where students can mark where they’re from.

Others host running chalkboards, painted ceilings, and floor-wide art projects. “Murals like that really give each section of Simmons their own little culture and personality,” Cha said. That creative culture helps foster a more grounded sense of belonging. “It’s nice to have that kind of nice community and relate with each other through silly things like chalking on the walls. Some people run on the walls. Just a form of activities.”

In the end, Simmons Hall seems to work best when its occupants adapt to it—rather than the other way around. The building’s intentions are legible, but unevenly delivered. “It just feels cavernous and empty all the time,” Temkin said.

“Even if people want to have some personality outside the door, you don’t even see it.” And yet for others, it’s exactly that space—literal and figurative—that allows something distinct to take root. “In terms of quality of life, maybe a little less,” Cha acknowledged. “But in terms of community... it’s really special.”

Realizing ambitious architecture is never easy—especially within the layered bureaucracy of higher education, even at a place as outwardly innovative as MIT. Simmons Hall exposed a deeper tension: between architectural authorship and institutional consensus, between design intention and the lived realities of students. MIT encourages bold thinking, but it also cultivates a culture of student self-governance— an environment where residents expect to help shape not just their community, but sometimes even their building.

In that context, Simmons Hall was always going to be a contested space.

And perhaps that’s its greatest achievement: not harmony, but provocation—a structure that continues to challenge, absorb, and reflect the evolving community it was always meant to serve.

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DESIGN

From Montréal to Qinhuangdao, Moshe Safdie has spent six decades rethinking how we live together at height. In this conversation with Casey Mack, he revisits the Habitat legacy— and what it means to build generously in an age of exclusivity.

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Casey Mack In revisiting your work for Vertical Urbanism, what struck me was how the idea of “Habitat” seems to be tied to a concept of abundance. There’s a generosity embedded in the ethos—an ongoing commitment that evolves through questioning and refinement, rather than becoming fixed.

That feels especially rare in architecture.

It also feels political, in a quiet but persistent way. Mies, for example, seemed to decide at some point that he’d solved the housing tower—no need to rethink it. But your approach remains open-ended, responsive. Greenery and nature are integral to that, but not, as you’ve said, as “a one-liner.”

They’re part of a deeper system.

Looking at Qinhuangdao, it feels almost like a sequel to Habitat 67. With that earlier project, you had the extraordinary situation of a thesis becoming a realized building—the apotheosis of any student’s dream. But Qinhuangdao also emerged from a speculative framework, didn’t it? I came across the “Vertical Urban Window” studies from your practice’s fellowship research, and I believe that’s where this version of Habitat took shape?

What strikes me about both Habitat 67 and what you later called “Habitat 2.0” in China is this recurring pattern: first comes the speculation, and then you find the site where it can be realized.

That’s incredibly rare—and remarkable. So you’d already been developing Habitat ideas again by, what—2010?

This discussion has been edited for concision and clarity.

Moshe Safdie We actually started a bit earlier—sometime in the early 2000s.

CM And what was the transition like from that phase of independent conceptualization—especially your concerns about surface area, plumbing runs, and other technical aspects —into an actual commission?

MS It came in sequence. After Habitat 67, there was a wave of unbuilt iterations—New York, Puerto Rico, Tehran, and Israel.

Then, for a while, there didn’t seem to be any new opportunities.

So we shifted to museums, public buildings, institutional work.

Around 2000, we launched the Safdie Architects Research Fellowship. The first cycle focused on towers in the city—not necessarily residential. We analyzed around 10 submissions for Ground Zero, which led to broader questions: How do you cluster high-rises? How can they connect at different levels?

Can you create public space above the street?

The following year, we ran another fellowship—this time explicitly revisiting Habitat, but imagining it at higher densities,

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Right— Design sketch

by Moshe Safdie for Habitat, Montréal, 1967.

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with mixed-use programming. We developed several prototypes and ultimately selected four systems, each with different priorities.

One system eliminated the inclined elevators of the original Habitat, which had doubled as both structure and circulation.

Instead, we focused on straight-line plumbing—more efficient— and simpler structures. The idea of prefabrication also evolved.

We had one we called the “in-and-out” system: a vertical structure that produces stacked terracing, with horizontal streets cutting through.

Another model kept the inclined massing but used vertical cores—the structure resolves itself through a kind of counterbalancing: one portion inclines this way, another that way, and by the time they meet at the base, it’s vertical.

And then there was the “urban window”—a completely vertical structure, with three layers: public realm at the base, offices in the middle, and mostly residential above. It reached up to 75 stories, but retained a sense of air and porosity.

Every unit had a real garden, and where that wasn’t feasible, we used compensating balconies.

CM

So that became the basis for Qinhuangdao?

MS Exactly. That was the genesis. Qinhuangdao became a testbed. It was purely residential—no offices, no commercial program—which allowed us to really test the architectural logic.

And it fit the site perfectly. The building sits right on the ocean, and the city was deeply concerned about megadevelopments blocking the view from behind. Our scheme offered something more porous, more respectful of its coastal setting.

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Left— The pioneering Habitat 67 was created for the Montréal Expo of that year, when Safdie was still a graduate student.

Opposite page— Prefabricated modules being lifted into place during Habitat 67’s construction.

Right— An axonometric section reveals the complexity of the Habitat’s interlacing of skybridges, modular units, and utilities.

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Revisited: Habitat 67 number 4, 2018: photograph

by James Brittain from a series.

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Revisited: Habitat 67 number 5, 2018: photograph

by James Brittain from a series.

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CM It really is amazing how porous it feels. It’s not overwhelming.

MS Exactly. It feels reasonable. They built it in two phases, and it sold like hotcakes—entirely within the open market.

No subsidies, no incentives. That’s what’s so impressive. We’re used to World’s Fair-style conditions where you can do one-off experiments. But here, it worked in a real commercial context.

Much of our early work was based on the idea of horizontal streets. In Habitat 67, those occurred every three floors. In later theoretical systems, it was every two or three—assuming that once you get off the elevator, you might go up or down one level.

Designing duplexes also allowed for cross-connections.

But it’s tough to implement horizontal street systems today, especially in China and Saudi Arabia. In China, the idea of luxury is tied to a private elevator that drops you right into your unit— or almost. In Saudi Arabia, it’s partly about privacy norms, but also a cultural preference for autonomy. The horizontal street is inherently social. And that doesn’t align with how super-luxury is imagined in either context.

CM Right—where super-luxury might even mean driving your car up to your unit.

MS Exactly. In our own project, even though we had elevators placed [at two points], and anticipated horizontal circulation between them, we ended up adding interim elevators just to shorten the corridors. That was a compromise—less efficient, and definitely less communal. But we had to accommodate very regional expectations.

CM Is the Qinhuangdao project luxury housing?

MS Not exactly. I’d call it upper-middle-income. Some units are owned by local government officials; about half are second homes from Beijing, and the rest are owned by locals.

Another one of our non-luxury housing projects is Sky Habitat, which was built on the periphery of Singapore, where there’s no luxury housing market. It’s really for working Singaporeans. I’d say middle- or upper-middle-income, but by Singapore standards, more like solidly middle-class.

The biggest difference with luxury would be location— true luxury housing tends to be central.

CM And what about the bridges in Singapore? You’ve mentioned how their appeal varies in Saudi Arabia and China.

Is there a different attitude there?

MS Yes. Singapore has a tradition of horizontal access— especially in HDB [Housing & Development Board] housing, which typically uses single-loaded galleries. So the idea of bridges or shared horizontal streets fits well within that context.

We’ve done several housing projects in Singapore. One was The Edge on Cairnhill. It’s three towers—each with one apartment per floor—linked by bridges and elevators. That setup avoids duplicating fire stairs and other systems. The units are large—2,500 sq ft (232 m2) or more—with glazing and windows on every side, even the back. Total privacy, but panoramic access.

I think the floor plate is approaching 3,000 sq ft (279 m2)— and that’s in luxury housing. There are even duplexes. But in

Upper right— Section / elevation.

Above— Typical floor plan, Habitat Qinhuangdao.

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Lower right— Site plan, showing footprint of a series of stacked residential blocks.

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Overview of Habitat Qinhuangdao in China.

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Top— View from a skygarden at the middle datum line of the complex.

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Above left— The towers and gaps between are oriented to maximize sea views.

Above right— The setbacks and intermittent park spaces break down the massive scale.

middle-income housing, like in Sky Habitat, residents are more socially inclined. The streets actually work. I’ve been back recently—lots of kids, playgrounds, swimming pools, amenities on the rooftop and at ground level. Honestly, I’ve never seen anything quite like it in the United States.

Top— The Edge on Cairnhill, Singapore has large units, one per floor, in three linked towers.

Bottom— Typical floor plan, The Edge on Cairnhill.

CM That resonates with some of what I’ve seen in my research— particularly in Japan, where “streets in the sky” seem to function just fine despite the criticism. That said, I haven’t seen them go much higher than the 20th floor.

MS That makes sense. In our case, it was the 25th floor. The idea was to create a kind of public ground at that level, running horizontally across a series of buildings. It was designated for community facilities, retail, and to serve the adjacent offices.

Then you’d have a more typical public realm at street level.

CM Right. That question of height reminds me of Form Follows Finance by Carol Willis.

She traces the history of early commercial skyscrapers in New York and Chicago, and one idea that stuck with me is “economic height”: the maximum profitable height before structure and core start eating into your returns. It made me wonder—do you have a kind of “ecological height” in your habitat work? A point where the system starts to break down in terms of wind, green space, or usability?

Some European studies now argue that anything above 12 stories carries a carbon penalty you can’t offset through low operational energy. I’d love to hear how you think about height from that angle.

MS I’m increasingly leaning toward less height— exploring compactness without sacrificing amenities. A singlefamily home, for instance, offers privacy, outdoor space, good light—and it’s structurally cheap. But in cities where land costs 10 times more than construction, that model becomes unaffordable.

As density increases, those qualities—light, outdoor space, even privacy—become technically difficult and financially prohibitive. The higher you go, the more complex the core, circulation, and structure. Eventually it all becomes heroic.

Singapore doesn’t have strong wind loads like Miami or the Gulf Coast, so height there isn’t constrained by storms.

But land value still drives everything.

In Western cities, the irony is: allow more density, and land prices rise further. In D.C., where building is capped around 11 stories, land value is linked to that cap. In Jerusalem, I fought to cap at 12—but lost. Now we’re seeing 30- and 40-story towers.

But I still believe you can achieve impressive densities without going super-high.

Many towers have emerged in the last 20 years on the Brooklyn and Queens shoreline. In that context, maybe 50 or even 75 stories make sense. You’re building for the uppermiddle market, and land values are already set.

But if I’m designing a new city? I wouldn’t go that high.

CM Right. And then there are shadow impacts—and in clusters, towers start blocking each other’s views.

MS Exactly. We studied that in the fellowship—residual views in dense high-rise clusters. It’s a complex issue.

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Below— The Crystal is a massive, 296-m-long skybridge spanning the tops of four towers at Raffles City Chongqing, with distinctly programmed modules within.

CM Zooming in again—thinking about Qinhuangdao with reference to Montreal—there was a big focus in Montreal on defining the concrete units: box size, the structural grid, whether the grid referenced the interior or exterior of the boxes.

That whole era was really about aggregation.

But your more recent Habitat projects feel different.

Aggregation is still there, but it seems like massing leads, and the units find themselves within it. Was there a guiding module at Qinhuangdao we don’t see? Or were standards set by the developer? How much freedom did you have?

MS Unit sizes and balconies were quite prescriptive.

But the bigger question—what construction system is best —that’s still unresolved for me.

With Habitat 67, I believed a three-dimensional module made the most sense. You could pre-finish it and assemble it on site. And we did that, partially: bathrooms, kitchens, wiring, windows, insulation. But the box wasn’t fully sealed, which created limits. We also ran out of time—some units had to be finished on-site.

The idea was solid, but we went too wide. The modules weren’t highway-shippable, so we had to build a plant on-site.

That’s only viable if the plant can move—or if the project is big enough to justify the cost.

Weight was another issue—each module was 70 tons.

Today we could lighten that with better concrete or steel. But ideally, you’d want something around 12–13 ft (3.5-4 m) wide to make it truckable. Even then, you’re still shipping a lot of volume.

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used it, though it hasn’t moved forward. We also worked with a modular company that normally does cookie-cutter hotels using 12-ft-wide boxes. Together, we figured out how to combine two of those into a 24-ft (7.3-m) unit.

CM Made from mass timber too?

MS Yes—CLT panels, laminated beams, and columns.

We even designed a system with corner columns that could replicate the Habitat concept of crossing over modules. So: column, column, column, and CLT in between.

You can leave the ends open and create continuity, with the timber units joined like Lego blocks. Structurally it works— and you can solve sound issues by duplicating the floor slabs and insulating. We took that study to eight floors and achieved considerable density. But no, it’s not built yet.

CM Still, it sounds promising.

MS We hope to build it. But at large scale, timber becomes less viable. You’re back to panelized modular systems—prefab bathrooms, kitchens, and so on—rather than full 3D modules.

And the jury’s still out on what’s most efficient.

You can’t answer that question at the scale of one project.

That’s the difficulty. Right now, most construction—even in China—is still wet. Concrete columns and beams poured on site, partitions going up by hand.

Just like any conventional construction site. And yes, it’s possible to make that more efficient, but change is hard in this industry.

Upper right— A dining space in the Crystal.

Lower right— Raffles City Chongqing is on one of the city’s most prominent sites, at the confluence of the Jialing and Yangtze rivers.

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CM Still, it feels like there’s a natural resonance between Habitat’s underlying biophilic ethos and the promise of mass timber.

MS I agree.

CM Thinking about Sky Habitat in Singapore—you’ve spoken admiringly about the way Singapore supports high-quality maintenance. Marina Bay Sands, Sky Habitat—they seem to thrive because the city commits to long-term upkeep. That kind of maintenance culture feels worlds away from the United States.

Singapore’s HDB housing model is often cited as exemplary. It’s deeply integrated with pensions and welfare, and manages to house people of all income levels in high-quality buildings. Vienna gets a lot of attention too. But Singapore seems like a system we could try to learn from—if not wholesale, then in parts.

But I wonder: while there’s so much attention paid to Singapore, is there anything in China we’re overlooking?

Something positive that’s getting overshadowed by things like the Evergrande crisis and the financialization of real estate?

Is there something in China’s housing culture or production that’s worth learning from?

MS There’s a real sense of adventure in Asia right now.

That’s the biggest difference.

Take Hudson Yards in New York. It was developed by one of the biggest firms in the United States, with all the marquee architects—and yet, it’s a failure in terms of public realm.

It’s a disgrace. Architecturally, too, it’s disappointing.

Compare that to what we built in Chongqing. It’s not a Habitat project, and it’s very tall, very dense—but the public realm is extraordinary. I hadn’t been back since COVID— it opened during the pandemic—so when I visited, I was amazed. The parks were full of people, the spaces were alive.

It was affirming.

So yes, there’s something in Asia—whether in China or Singapore—that allows you to do things we just can’t do here.

But the other side of the question is: will we ever have a situation where you start investing in developing schemes that are amortized over time, or a large number of units, that allow you to explore things?

I still marvel at the industrial quality of things we do mass produce. Cars, for example. You spend $50,000 and get extraordinary precision and performance. But I just did a modest renovation on a little carriage house—added a bathroom.

Left— Sky Habitat, Singapore (2015).

Right— Sky Habitat notably features planted bridges connecting the towers.

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The cladding alone cost $120,000. That’s more than two cars.

It doesn’t make sense.

So yes, I keep wondering: when will we finally crack this? I’m 87. We keep being promised new materials— fireproof polymers, ultra-strong composites. But they never arrive. Timber has improved, but has limits. Glass tech has advanced. But the basic bones of buildings? Still steel or concrete.

CM I’ve long been interested in questions of control in architecture… What’s striking, across projects like Marina Bay Sands and Chongqing, is how accessible your public spaces seem to be—at least in their ambition.

I remember you saying that Marina Bay’s public areas were accessible 24 hours a day. How much of that openness is something you’re able to push for? Can you actually demand that public space be kept truly public, rather than gated behind turnstiles or financial controls?

MS It’s a real tension—between public accessibility and exclusivity. At Marina Bay Sands, for example, the galleries and shopping areas were of course designed to be open to the public. That aligned with the developer’s interests—they wanted foot traffic. No problem there. And integrating those interior spaces with the waterfront into a seamless public experience? Again, no conflict.

Where it got more complicated was in the hotel atriums.

I wanted those 10-m-wide passages to function like true public realm—open 24/7. I convinced the client by arguing that if we kept them public, they could be excluded from the building’s gross floor area (GFA), which helped with compliance. That worked.

But now, 15 years later, those passages are too successful.

They’re crowded with people—many not staying at the hotel. The client wants to increase the sense of exclusivity, so now there’s discussion about whether to limit access.

CM Right. As properties get more luxurious, the pressure to gate the public out increases.

MS Exactly. In residential projects, it’s even trickier. In Montreal, I donated my own Habitat 67 unit to McGill University to make it publicly accessible. That meant organizing public tours through a private building— understandably, a sensitive issue for residents.

Montreal’s relatively low-crime, so people were okay with it. But if you tried that in a city like Chicago, you might face stronger pushback—purely for safety reasons.

CM Do you think it’s possible to design large-scale projects— Hudson Yards-scale projects—that make a healthy distinction between public and private realm?

MS Yes, but you have to be deliberate. The key is to make public spaces truly accessible—and, just as importantly, connected to the flow of the city. If you create a beautiful plaza on the 25th floor with no connection to how people move through the city, it’ll be a dead zone.

At Marina Bay, by contrast, we’re getting extraordinary foot traffic. That’s a sign it’s working.

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CM I haven’t been to Singapore yet—it’s high on my list.

MS You should go. There’s a lot happening—local architects doing strong work, and also some interesting contributions by international firms.

CM It’s also one of the world’s greenest cities—literally. Greenery plays such a key role in your projects there, and in Qinhuangdao too. But greenery is sometimes dismissed as a kind of aesthetic cliché. I’m wondering if, from your experience in Asia, you’ve encountered more admirable or rigorous approaches to sustainability—whether through regulations or design culture?

MS That brings me to a favorite subject: we’re mismeasuring sustainability. Look at LEED, Green Mark, and similar programs.

They can rate a terrible building as Platinum. Why? Because the criteria they measure—like energy use—are clear and quantifiable. But livability isn’t really part of the equation.

Take a notorious example: someone at UCLA proposed a dorm with tiny, cell-like bedrooms and a few shared living spaces at the perimeter—no daylight, no windows. And it earned a Platinum rating. That project didn’t get built, but it shows the problem: it ticked the boxes on energy performance, but was fundamentally unlivable.

CM That’s horrifying—and not uncommon.

MS Then there’s the flip side: cynical greenwashing. Big firms walk into a pitch and say, “We’re all about biophilia.” Then they present a conventional building with a few trees stuck on top.

You have no idea where the trees are rooted or how they survive.

It’s just a green bluff.

We need to ask: When is green really green? To me, it’s green when people can sit in it, live in it, use it—not just look at it.

And when it’s integrated into the building in a way that’s nearly maintenance-free.

The rating systems need to evolve. For example, why not require minimum daylight access? In Germany, workspace standards specify how far a desk can be from a window.

That’s meaningful. Without those kinds of livability metrics, the ratings become about abstract numbers rather than actual human experience.

CM And it seems like, more and more, firms are playing the system.

MS Absolutely. I see it constantly.

CM One of the things I find especially frustrating about LEED is that it often rewards more material use. You get points for including 20 different materials with environmental product declarations— while using just one really efficient material doesn’t count for much.

Just a final couple of questions. I teach a vertical urban utopias thesis class at Pratt, and I often ask my students a classic sciencefiction prompt: “What pisses you off?” I’m curious—what’s irritating to you right now in architecture, and how does that motivate your current work?

MS During the postmodern wave, I felt quite alone in thinking it was all nonsense. And I suppose I’ve lived long enough to watch

Above—Marina Bay Sands, Singapore.

Original three towers and Skypark pool (2012) at right; under-design music arena and fourth tower at left.

it disappear—though in places like Dubai, you still see its afterglow: earth-tone façades, decorative roofs.

But the bigger shift I’ve seen is this: for 20 years, people said Habitat was a one-off, irrelevant. Now it’s gone mainstream. Firms like BIG, Herzog & de Meuron, Mecanoo—they’re all exploring versions of it. Fractal massing, more terraces, more gardens—it’s become common. That’s satisfying to witness.

What still irritates me is architecture that’s purely compositional or formalist, ignoring program and livability. Some of Zaha’s or Libeskind’s work falls into that category. That said, there are moments of genuine spatial invention too. It’s a spectrum.

CM Which current projects are you really excited about?

MS We’re working on a $4 billion expansion to Marina Bay Sands—another tower and a music arena.

It’s ambitious. We’re also designing a ski resort in Killington, Vermont—my client’s goal is to make it even better than Stowe.

And we have housing underway in Riyadh. It’s more conservative there, but it’s interesting.

CM Thank you for sharing your time.

Credits— Unless otherwise noted, all images courtesy of Safdie Architects.

MS

There’s a lot to talk about.

This issue’s Archive features a selection of Moshe Safdie’s drawings that track Habitat from his student thesis (p. 148).

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DESIGN

In Curitiba, AGE 360 reimagines the residential high-rise not as a status symbo, but as a framework for connection —combining a concrete exoskeleton with communal spaces to propose a new kind of vertical belonging, writes Greg Bousquet. Photography by Joana França.

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Designing a building like AGE 360, in Curitiba, was an exercise in attentive listening and creative articulation. It began with a sensitivity to the site—its topography, regulatory framework, and urban history—and the desire to shape an architectural language that could respond to these conditions with both density and lightness. The challenge was clear: to create a landmark in the city’s skyline that transcended mere iconography.

We envisioned a tower that embodied a new mode of vertical living—contextaware and bold in its propositions.

The Ecoville neighborhood, where AGE 360 is located, is a territory in flux. Historically characterized by low-density, horizontal development and generous greenery, it has undergone a rapid verticalization over recent decades—often in ways disconnected from the surrounding urban fabric. We saw in this not a constraint but a design opportunity: to reposition verticality as a means of integration—with the landscape, the city, and its people.

Curitiba has long held a reputation for pioneering urban planning. AGE 360

engages with that legacy while also questioning the limitations of conventional residential typologies.

It argues that vertical living need not entail repetition or isolation. Quite the opposite—it can offer a framework for what we call “vertical belonging.”

Architecture plays a critical role in confronting climatic, social, and even migratory challenges, particularly given the scarcity of available land.

Rather than defaulting to predictable, controlled environments, we must design spaces that accommodate complexity and foster interaction.

Reclaiming Verticality From the beginning, the client presented an ambitious brief: a 124meter residential tower that would serve as a new visual anchor for the city.

It was a bold commission, yet unusually open to experimentation—a rare alignment of vision and trust.

We initiated the process with an intensive collaboration between architects, engineers, and the developer.

Early workshops helped establish a

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Left— Site plan emphasizing AGE360 tower’s urban permeability at ground level.

Above— The tower seeks to extend the essence of the surrounding Barigui Park upwards, integrating greenery into its façades and terraces.

common language across disciplines.

This alignment ensured that aesthetic, technical, and commercial decisions would reinforce, rather than undermine, one another. Today, architectural responsibility is inherently collective.

In an era of climatic and social adversity, the architect must act as an orchestrator of interests, transforming conflict into spatial opportunity.

Local zoning regulations, often viewed as constraints, became generative tools. Setbacks, solar access requirements, and height limitations were translated into spatial parameters. We conducted more than 40 volumetric simulations to optimize the tower’s placement— balancing views, cross-ventilation, and contextual sensitivity. The chamfers and setbacks that now define AGE 360’s silhouette emerged directly from these studies. The final form is a synthesis of what the site asked of us and what the city allowed us to do.

At Architects Office, every project begins with an investigative process rooted in our contextual, glocal, and tactile approach. We draw from both local and global perspectives —always attending to land, climate, and community.

Structure as Expression One of the central design challenges was how to create expansive, open interior volumes without compromising either structure or façade. The solution emerged from the structure itself: a concrete exoskeleton that carries the tower’s loads at its perimeter. This liberated the interiors from columns, enabling flexible floor plans and panoramic views.

Together with the contractor, we developed dozens of prototypes to achieve the desired uniformity of tone and texture in the concrete. This was not merely an aesthetic concern; the exoskeleton was tasked with expressing both structural logic and poetic intent.

For us, material innovation is about balancing authenticity with performance.

The structural system posed major technical demands. Our dialogue with engineers was particularly intense when validating the feasibility of the exoskeleton and the cantilevered slabs.

Construction methods had to adapt —requiring prefabricated formwork, careful sequencing, and close integration of the planted terraces.

Personally, AGE 360 represents a turning point. It crystallizes a trajectory I’ve been pursuing for years: toward Vertical Urbanism 4 II / 2025 FOCUS

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AGE360’s faceted volume reshapes the city’s skyline with its sculpted geometry and exposed concrete exoskeleton.

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Boston University’s main campus sits on the southern shore of the Charles River, directly across from MIT and downstream from Harvard University.

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Left and below— The tower’s wellness spaces are finished in natural wood and planted with wind-resistant, low-maintenance native species.

architecture that is more contextually grounded, more process-driven, and less object-focused. Each project becomes a singular interpretation of its time and place.

Designing for Belonging A key innovation was the relocation of shared amenities from the ground floor to the middle of the tower. The pool, spa, and communal areas were elevated to create a new kind of social threshold—both contemplative and connective. In doing so, we aimed to foster not just vertical living, but vertical community. Residents share not only a height in the skyline, but a horizon.

These shared spaces are clad in natural wood, offering warmth and softness against the mineral presence of concrete and the integrated greenery.

Even 60 meters above ground, the building encourages reconnection with nature. Architecture, in this context, must support communal experience and social interaction, rather than isolation.

Vegetation plays a structural role in the project. Built-in planters were integrated into the terraces and directly accessed from each unit. This not only facilitates maintenance but reinforces an 76

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Above right— Common areas on 22nd floor.

Below right— Standard floor plan.

everyday relationship with greenery.

Species were selected for resilience to wind and sun, ensuring long-term sustainability with minimal upkeep.

These gestures, though subtle, have measurable impacts—on residents’ well-being and the building’s broader urban ambiance. Architecture becomes a wellness infrastructure, capable of generating ecological and emotional value.

A New Urban Legacy Though Curitiba is a mid-sized city, its urban challenges mirror those of larger metropolises. In this context, AGE 360 is a case study in intelligent densification. It rejects the model of the isolated tower and proposes instead a verticalism grounded in wellness, social connectivity, and long-term livability.

Projects like this may offer guidance for cities across the Global South, where urbanization is accelerating and the demand for housing is intensifying. The question is not just how to build higher —but how to build with depth: socially, ecologically, and spatially. Architecture, in this sense, must act as a conscious art—shaping the present while offering a more humane legacy for the future.

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Right— A triple-story exterior terrace on the 17th floor provides expansive views of Boston, including the Charles River and Fenway Park.

Left— Key section showing the intent to establish a “vertical campus.”

Rotating around the central core, the cantilevered volumes are conceived as neighborhoods that offer each department its own dedicated outdoor space.

Aerial view of AGE360: the tower rises 124 meters above Curitiba.

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Right— Typical floor plan: the design provides access to natural light and views and creates multiple collaboration spaces.

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Left— Ground floor plan: with the tower anchoring the corner site, the ground floor is primarily given up to the public realm, offering areas for collaboration and study, and a café.

Credits Owner/Developer: Boston University Architect: KPMB Architects Structural Engineers: Entuitive; LeMessurier MEP Engineer: BR+A Consulting Engineers Project Managers: Brian Ballantyne Specifications; Compass Project Management Group Contractors: Suffolk Construction Company, Inc. (main contractor); Prime Steel Erecting, Inc. (steel)

Other Consultants: Acentech (acoustics); Nitsch Engineering (civil); Transsolar Energietechnik GmbH (environmental); Entuitive (façade); Jensen Hughes (fire, life safety); Ricca Design Studios (food service); Skillings & Sons, Inc. (foundation); Haley & Aldrich (geotechnical); Robbie McCabe Consulting, LLC (interiors); Richard Burck Associates

(landscape); The Green Engineer (LEED); Rubin and Rudman LLP (legal); Dot Dash (lighting); Fort Point Associates, Inc. (planning); AECOM (traffic); Soberman Engineering Inc. (vertical transportation); Entro Communications Inc. (way finding); RWDI (wind) Material Suppliers: Ferguson Neudorf Glass (cladding); Canatal (steel)

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Left— Section: AGE360 has an exoskeletal concrete structure.

Above— Panoramic views of the city from a shared terrace.

Below— Communal swimming pool on the 22nd floor.

Credits Developer: AG7 Realty Architects: Architects Office; Triptyque Main Contractor: TEICH Engenharia Structural Engineer: Kálkulo MEP Engineers: Lumini Projetos e Soluções; Michelena Climatização; Vectra Engenharia Interiors: Suíte Arquitetos Landscape Architecture: Renata Tilli Fortes Acoustics: Relacus Realizações Acústicas Foundations: MG&A Lighting Design: Estúdio Carlos Vertical Urbanism 4 II / 2025 FOCUS

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DESIGN

A slender tower on a four-meter wide site in Mexico City is a model of urban precision—bold, adaptive, and barely possible, says Francisco Brown.

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In the rarefied air of Mexico City’s Polanco district— amid its broad avenues and speculative high-rises— one building stands apart not for its scale, but for its restraint. A rationalist sliver of architecture, Ferrocarril de Cuernavaca 780 occupies a slender parcel hemmed in on all four sides by a labyrinth of jurisdictional and infrastructural constraints. Designed and developed by Hemaa Arquitectos, the building is just 4.3 m wide at its narrowest façade, expanding to approximately 10 m at its widest. In an environment characterized by volatile development politics and a rapidly evolving office market, the project emerges as a model of urban intelligence—negotiating legal, environmental, and spatial complexities with design precision and business intuition.

“It’s not a triangular lot, as it might seem,” explains Santiago Hernández Matos, co-founder of Hemaa

Left— The black façade articulates its rational steel frame and hybrid structural system, paired with high-performance reflective glazing and operable windows.

Above— Site plan: setbacks imposed by buried pipelines, zoning regulations and seismic requirements, forced the building into its elongated form.

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Arquitectos. “It’s actually rectangular—but riddled with setbacks. All four sides were constrained due to pipelines from Pemex (Mexican Petroleum) and MetroGas, a gas distribution company that pass barely 1.2 m [4 ft] from the site.” The presence of gasoline and gas conduits just beneath the sidewalk demanded constant industrial oversight and dictated much of the building’s structural logic —but it also catalyzed the architectural form.

Hemaa served not only as the building’s designers but also as its developer —a hybrid role that proved essential. “It took two years of unraveling regulations,” Matos recalls. “But that period also gave us time to structure the project around opportunity, not just restrictions.” That dual agency allowed the architects to engage directly with municipal authorities, unlocking latent development potential while safeguarding

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Left— Seen from the adjacent now-unused train tracks, the building’s narrow form aligns with the former Ferrocarril de Cuernavaca rail corridor, from which it takes its name.

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Opposite page— The long elevation reveals the building’s shallowness, only 30 feet (9 meters) at its maximum.

Below and bottom— The building’s narrowest elevation is just 14 feet (4.3 meters) wide. From inside, the floor-to-ceiling glazing frames the city beyond.

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clients like Amazon, Google, and American Express.”

“We ended up with a more dynamic program than originally planned,” says Matos.

“It’s one of the unexpected gifts of the pandemic.”

This adaptability is further enhanced by a robotic parking system—developed with a German firm—which houses 126 vehicles within the building’s constrained footprint. Seamlessly combined into the architectural and structural design, the system exemplifies how technology can resolve density-related spatial dilemmas and city code.

Sustainability was also a guiding principle.

The building is LEEDcertified, with an incorporated Building Management System (BMS) that dynamically calibrates lighting, HVAC, elevator usage, and power consumption based on real-time occupancy and seasonal fluctuations.

High-performance glazing with carefully applied reflectance levels, operable windows, and balconies

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against excessive bureaucratic compromise.

The outcome is a rationalist steel tower that feels simultaneously lean and robust. Its integrated structural system—composed of steel framing with concrete elements—ensures openplan, column-free floors while meeting Mexico City’s stringent seismic codes.

The minimalist structural grid, paired with an efficient core-and-shell strategy, yields elongated, light-filled volumes with a degree of programmatic neutrality that encourages flexibility across tenancy types.

Initially conceived as a corporate office building, the program evolved midconstruction in response to pandemic-era shifts in space usage. Today, the high-rise accommodates a range of uses—medical offices, a yoga studio, corporate training spaces, and a rooftop event venue. The latter, with panoramic views of the city, has become a vital revenue stream, “rented frequently by

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Left— Upper-level view from the narrowest end, where fullheight glazing reveals the building’s historical axis with the former rail corridor.

promote daylight autonomy and passive ventilation— essential qualities in a post-COVID context where access to fresh air and individual control have become tenants’ priorities.

Perhaps most compelling is the project’s engagement with the public realm.

Forgoing perimeter fencing or barriers typical in the city, the architects opened the ground floor as a public landscape and commercial node. The street level includes a café and seasonal pop-up stores that have become a popular morning ritual stop for local runners, neighbors, and frequent visitors. In collaboration with landscape architects DLC Arquitectos, Hemaa crafted an interface of 90

planters, benches, and porous urban edges that connect seamlessly with the planned linear park along Neuchatel Street.

“That public space wasn’t an afterthought,” Matos emphasizes. “It was part of the negotiation with the city—and it’s what unlocked the project’s full potential.”

Ultimately, Ferrocarril de Cuernavaca 780 exemplifies what becomes possible when design and development converge within a single vision.

Far from being an exercise in compromise, the building is a case study in architectural clarity born of constraint, where each formal and spatial decision serves both programmatic adaptability and urban generosity.

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Above— Interior view onto the roof terrace, a flexible outdoor space with panoramic city views, now used for events and gatherings.

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Left— The lobby’s curved glazed wall softens the building’s entry, easing circulation and drawing light into the narrow space.

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Below— Floor plans: typical underground parking level and ground level.

Opposite page— Floor plans: typical office floor and roof top level.

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Left— Long section revealing the full extent of the robotic basement parking system, which fits 126 vehicles within the building’s compact footprint—an engineered solution to extreme site constraints and city code requirements.

Above— Façade detail showing the layered assembly of the building envelope: a rational steel frame infilled with high-performance glazing, operable windows, and balcony elements—designed for thermal efficiency, daylight autonomy, and passive ventilation within a tightly constrained structure.

Credits Architecture: HEMAA Design and Construction Team: Santiago Hernández Matos, Alejandra Tornel Cahue, José Miguel Fainsod Castro, José Pedro López González, Alonso Sánchez Toscano, Adriana Aguirre Becerra, Andrea Motilla Chávez, Daniela Parra Orozco, José Miguel Santivañez Gómez, Juan Octavio Ferreira, Mónica García Cruz, Patricio Salgado Rodríguez Structural Engineer: PESA MEP Engineers: CYVSA; DEC; Garza Maldonado Special Engineer: TecnoBuildings Landscape Design: DLC Architects LEED Certification Comissioning: Alejandro Trillo + Gabriel Morales Architectural Model: Taller Cuatro Cuartos Others: Omar Sad / Augusto Álvarez

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TECH

Wood Up combines hybrid structure, beech glulam, and regulatory firsts in a testbed for dense, low-carbon housing in Southeast Paris, says Francisco Martinez Selles.

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Left— View from across the Seine, showing Wood’Up’s doubleheight timber grid and central void aligned with the Parisian roofline.

In the Bruneseau regeneration district in Paris, is a prototype for low-carbon urban construction designed to test both architectural potential and regulatory limits. At the edge of Paris Rive Gauche, facing the Seine and backed by the Boulevard Périphérique, it stands at the threshold between city and suburb. It occupies a site shaped by infrastructural disconnection, yet aims to propose a more connected, materially expressive model of dense urban living.

Our practice, LAN (Local Architecture Network), won the competition launched by the City of Paris, which sought to encourage innovation in timber construction.

From the outset, it was treated not just as a residential project but as applied research: an opportunity to advance 98

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the technical, regulatory, and formal language of timber urbanism.

Wood Up’s structural system is hybrid. A three-story polished concrete plinth—needed to bridge the sevenmeter height difference between the riverside quay and the boulevard— anchors the building to its uneven site.

Above this sits a timber superstructure built on a 3.9-m grid, developed through full-scale studies to find a rhythm that balances expressive clarity with daylight performance.

Originally, nearly all units were designed as duplexes, occupying a full grid cell each. That purity eroded in development, as smaller, single-level apartments were introduced to improve financial viability. Still, the overall framework remains legible: every second floor accommodates larger

Right— Stairway linking boulevard level to the Seine, integrated into the three-story precast concrete plinth that anchors the building to its sloped site.

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Left— View across the Seine toward Wood Up; the École d’Architecture de la Ville et des Territoires is adjacent, with the emerging ZAC Ivry-Confluences district visible in the background.

flats with private terraces, while smaller units without balconies are placed above.

Those that face the Périphérique feature narrower outdoor spaces—an architectural decision reflecting both acoustic conditions and patterns of use.

Externally, timber columns span two levels, reinforcing verticality and providing depth for solar shading. These wooden structural elements—made from Normandy-sourced beech and Douglas fir—are visible throughout the façade.

Their presence was not a given. Fire safety regulations in France no longer permit exposed timber in high-rise façades. To retain the expression of wood, we undertook an intensive process of modeling, simulation, and laboratory testing to show that flame spread could be contained. We lost some details—timber balcony soffits had to be replaced—but kept the essential character intact.

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Left— View showing the double-height timber column grid—a remnant of the original duplex scheme— with narrower balconies on the Périphérique side.

Opposite page— View from the open-air stair landing, looking across the Boulevard Périphérique.

This negotiation with regulation shaped every part of the project. The stairwells, for instance, are open-air. By leaving them unenclosed, we were able to meet fire code requirements without expensive ventilation systems.

This strategy also allowed us to exclude the stairs and lobby from the building’s total floor area—since in French code, open-air spaces do not count toward a site’s maximum allowable buildable area. The result is a building that feels open, generous, and porous, while remaining tightly calibrated for spatial and financial efficiency.

Midway up the tower, a large communal terrace is cut directly into the structure—interrupting the rhythm of columns and offering views across the city. This gesture serves multiple purposes. It introduces a social hinge

into the vertical sequence of apartments; it creates a shared public space at the level of the average Parisian rooftop (roughly 24 to 25 m); and it brings the building into dialogue with its broader context.

Structurally, this void required a significant intervention: a transfer truss that redirects the loads from the columns above to those flanking the terrace. Such elements are more common in office or infrastructural projects, but here they were necessary to preserve the openness of the middle level. Initially, the entire eighth floor was to be shared space—a feature that helped the project win the competition—but this was later reduced.

Even so, the terrace remains an architectural and civic marker.

A similar approach shaped the lobby.

Though enclosed on some sides, it is

formally considered an outdoor space.

This allowed us to treat it as a kind of urban threshold rather than a conditioned interior, avoiding thermal and fire performance requirements that would have driven up costs.

A simple curtain wall fronts the Périphérique side, while the approach from the river offers a more ceremonious ascent, stitched into the site with stairs and ramps.

Many of the technical innovations in Wood Up are subtle but essential. The sliding doors that connect apartments to terraces, for example, had to remain perfectly horizontal. Unlike hinged openings, sliding systems cannot accommodate movement—and timber structures, by nature, move.

Our solution was to suspend the door frames from isolated steel brackets, Vertical Urbanism 4 II / 2025 FOCUS 103

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Right— Long-section.

The void is cut at the typical Parisian roofline height.

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effectively detaching them from the shifting structure like paintings hung on a wall. The gap is sealed with a flexible EPDM (ethylene propylene diene monomer) membrane, ensuring continuity of the thermal envelope while allowing independent behavior.

Thermal curtains were another carefully considered detail. Instead of using exterior blinds—ubiquitous in French housing—we developed a dual-layer curtain with a reflective aluminum outer face and a soft textile inner lining. These are installed as part of the architecture, and are in fact essential to the building’s energy compliance. If a resident removes them, the unit technically no longer meets regulation. While enforcement is unclear, the strategy allowed us to preserve a clean façade while ensuring thermal performance.

Wood Up is not a social housing project. The units are neither subsidized nor rent-controlled, and the larger terraces and best views belong to the more expensive apartments. But it does attempt to model a different kind of vertical domesticity—one that combines architectural clarity with material warmth, and economic realism with environmental ambition.

If there is a contradiction at the heart of the project, it is this: we are being pushed—by climate mandates, by city policies—to build in wood.

And yet, at the same time, the codes that govern safety increasingly forbid 0 us from showing it. Wood Up is one possible resolution. It takes regulation as a design tool, not a constraint, and proposes a way forward for timber urbanism that is both expressive and exacting.

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Left— Shared terrace cut into the middle of the tower, aligning with the Parisian roofline and marking a social hinge in the building’s vertical sequence.

Right— Partially enclosed lobby space treated as exterior to bypass fire and thermal regulations.

Far right— View from the shared void terrace, looking out across the Périphérique.

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Left— Upper-floor apartment with double-height living space—part of the limited remaining duplex units from the original scheme.

Left— Typical corner unit with sliding glass doors opening onto a private terrace; reflective thermal curtains replace external shading devices.

Above— Private terrace facing the city, with a horizontal fire-protection panel that also offers privacy from the overlooking apartment above.

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Glulam spruce beams

Left— Structural diagram showing the hybrid system: a concrete base with a timber superstructure, and steel transfer trusses redistributing loads around the central void.

Glulam beech pillars

Vierendeel steel beam Mixed wood/ concrete floors Concrete bracing walls

Steel ladder beam Concrete pillars

Credits Owner: Sémapa Developers: Gecina; La Compagnie de Phalsbourg; REI France Architect: Local Architecture Network 108 Vertical Urbanism 4 II / 2025 FOCUS

Structural Engineer: Elioth MEP Engineer: Sinteo Main Contractor: Maître Cube Environmental Consultant: Elioth

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Façade detail key 1. Terrace–Loggia floor complex: Wood decking on joists, installed on adjustable pedestals ; concrete flashings at fixing points for balustrades and two-layer waterproofing ; concrete slab 2. Concrete slab nosing: Prefabricated reinforced concrete slab, beige mass-tinted 3. Metal balaustrade: Powder-coated steel frame with flat uprights ; Powder-coated steel balustrade infill 4. Side wood cladding: 3-ply Douglas-fir panels, treated with fire-retardant stain, invisible fixings 5. Post head timber cladding: Gluedlaminated Douglas-fir cladding, treated with fire-retardant stain, invisible fixings 6. Aluminum external windows: Thermolacquered aluminium frame with a bay featuring sliding openings + opaque panel for maintenance 7. Internal timber edge beam: Glued-laminated spruce beam 8. C+D casquette: Powder-coated steel C+D “casquette” 9. Acoustic enclosed ceiling: Acoustic false ceiling with BA13 anti-vibration ceiling tiles 10. Thermal curtain: Thermal insulation curtain ; External reflective aluminium surface ; Rail-mounted 11. Wood – concrete slab

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TECH In a remote Alpine village, a 3D-printed concrete tower combines robotic fabrication with embedded structural reinforcement for the first time, write Benjamin Dillenburger and Michael Hansmeyer.

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In the Swiss Alpine village of Mulegns, rises Tor Alva (“The White Tower”), what we believe to be the world’s tallest 3D-printed structure. Commissioned by the Origen Cultural Foundation, the tower is intended as a beacon for the village—revitalizing it through architectural visibility and cultural programming.

The project seeks to seamlessly merge architectural experimentation with cultural activation. It functions as both a performance venue and a research prototype for digital construction. Developed through interdisciplinary research at ETH Zurich, it explores the ecological and economic viability of 3D-printed concrete while addressing the broader question of how design can respond to rural demographic decline.

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also demonstrates how computational design and robotic fabrication can expand architectural expression and technical capability.

From Enclosure to Exposure The spatial sequence of the tower leads visitors on a vertical journey—from dark, introspective chambers at the base to a luminous theater beneath a dome.

At the summit, 36 seats encircle a central stage, framed by eight slender columns and open to the surrounding landscape.

The structure blends interiority and outward view, creating a space for performance and reflection within a high-altitude setting.

Thirty-two columns define the tower’s structural and visual character.

At the lower levels, robust 3.4-m columns anchor the building. Above, more slender columns—some reaching six meters—intertwine to support the cupola. While each column is uniquely designed and ornamented, they share

Above— The cupola theater at the summit of Tor Alva seats 36, arranged in a circle beneath eight slender columns that open to the Alpine landscape.

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Above— From the summit of Tor Alva, visitors look out across the alpine valley surrounding Mulegns.

Below— The central staircase spirals through Tor Alva’s five levels.

a formal and material vocabulary that unifies the composition. The undulating surfaces of the columns animate with light and shadow as the day progresses.

This expressiveness is made possible by computational design strategies articulated at three scales. At the macro scale, the columns’ branching, bone-like geometries absorb lateral forces without requiring extra bracing. At the meso scale, spiral waves reinforce thin shells, both stabilizing and exaggerating verticality. At the micro scale, detailed ornamentation emerges from subtle changes in robotic extrusion—capturing the unpredictability of material behavior while referencing the baroque craftsmanship of the surrounding region.

Matter, Method, and Machine The 3D-printed concrete used in Tor Alva enables what the designers describe as “material-driven” ornament—form shaped not just by design intent, but by the properties and constraints of the Vertical Urbanism 4 II / 2025 FOCUS

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Tor Alva rises from the small alpine village of Mulegns, Switzerland.

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BIRDVIEWPICTURE

printing process. Adjusting factors such as extrusion speed and nozzle angle produces surface textures that cannot be fully anticipated in digital models.

To manage this unpredictability, the design team developed a “cookbook” of parameter sets, linking print settings to specific surface effects. This approach enables mass customization with a high degree of control, producing tactile richness at no additional cost.

Each column is fabricated from approximately 5,000 m of printed filament, measuring 25 mm wide and 8 mm high. The system includes an outer filament for surface articulation, a middle layer encasing steel reinforcement, and an inner filament forming hollow channels for posttensioned rods. The printing mix itself—white concrete blended with stabilizer and accelerator—cures quickly enough to support new layers while remaining pliable for bonding.

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HANSMEYER/DILLENBURGER

CHEWEI LIN

Top, right— Printed components are maneuvered through the fabrication hall.

concrete in complex geometries, while the other inserts reinforcement as printing progresses. After the main print is completed, additional steel rods are inserted and grouted into the hollow cores, enabling full structural performance. This marks a significant advance in digital construction: Tor Alva is the first multi-story building with fully load-bearing 3D-printed concrete columns that integrate reinforcement during fabrication.

Assembly and Afterlife Prefabrication took place over three months at ETH Zurich’s Robotic Fabrication Lab. Mid-sections of the columns were printed on-site, while bases and capitals were produced using hybrid methods that combined 3D-printed plastic formwork with cast concrete. These components were then transported to Savognin—10 km from Mulegns—for final assembly. Each floor was installed in a single day, allowing for 116

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Above, left— On arrival in Mulegns, column segments are lifted into place using cranes adapted for the steep, narrow terrain.

CHEWEI LIN

HANSMEYER/DILLENBURGER

Top, left— Columns are made in ETH Zurich’s Robotic Fabrication Lab, where dual robots extrude and reinforce bespoke concrete geometries.

Above right— Installers align and join each modular piece—base, shaft, and capital —completing one story per day during the short mountain build season.

rapid construction despite the short building season and logistical challenges of the mountainous site.

The project also takes disassembly into account. Designed as a temporary structure with a five-year lifespan in Mulegns, the tower can be dismantled and reconstructed elsewhere. Each column is made of three dry-connected components: a base, a shaft, and a capital. This strategy reflects a commitment to circularity and resource efficiency, positioning Tor Alva not only as a built artifact but as a mobile cultural and technological prototype.

The tower’s nonstandard forms— with their flowing contours and intricate surface detail—invite curiosity and touch. But beyond its novelty, Tor Alva is a serious proposition: a convergence of digital fabrication, architectural imagination, and civic ambition. It highlights a future in which construction is not just automated or efficient, but expressive, place-specific, and reversible.

Plan 4.OG

Plan 4.OG

Plan 1.OG

Right— Section.

Plan 1.OG

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Internal view during the construction phase.

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ANA ANTON

Position— Close-up of the texture, which has a tactile quality.

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Above— 1.OG

Floor plan Level 1.

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1.OG

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Credits Client: Origen Cultural Foundation Architecture Benjamin Dillenburger (ETHZ DBT) Michael Hansmeyer Team DBT: Ana Anton (Research lead), Elena Skevaki, CheWei Lin, Ming-Yang Wang,

Lena Kitani, Su Huang, Konrad Grasser (ZHAW) Supporting Structure Walter Kaufmann (CSBD) Alexandro Giraldo Soto, Lukas Gebhard; Lucia Licciardello Building Materials Robert Flatt (PCBM), Timothy Wrangler, Lex Reiter

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4.OG Above— Floor plan Level 4.

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RESEARCH PAPERS

This paper examines the ongoing challenges of ensuring fire and life safety in tall buildings, catalyzed by the 2017 Grenfell Tower fire.

While the incident prompted widespread concern and new attention within the tall building community, significant obstacles remain to establishing global best practices.

Drawing on CTBUH Fire Safety workshops and recent international case studies—from recladding efforts and combustible façades to wildfire exposure, e-bike batteries, and evolving evacuation strategies—the paper explores the intersection of technical design, regulatory inconsistency, and human behavior.

It argues for a more coordinated, contextsensitive approach to fire safety as building technologies and climate risks intensify.

Authors: Terri Meyer Boake Gary Strong Keywords: Cladding Evacuation Fire

NATALIE OXFORD (CC BY-SA)

Figure 1— The Grenfell Tower fire in London, June 2017, killed 72 and was a watershed moment in changing the dialogue around highrise fire safety.

The Impact of Grenfell It’s not that fire is deemed an uninteresting aspect of tall buildings to study, but the Grenfell Tower fire on 14 June 2017, which claimed the lives of 72 people, drew the attention of many CTBUH members to a Fire Workshop at the CTBUH 2017 Conference in Sydney. Workshops were a new addition to the CTBUH International Conference that year, and though I have no technical training in fire, I decided to participate because, as an architectural educator, I wanted to understand what happened and be able to change the awareness of students who will enter the industry to prevent such fires in the future (see Figure 1).

While the workshop attendance in Sydney was full, post-Grenfell, since then the Fire Safety workshop attendance has dwindled. Perhaps there are simply more workshops to choose from. Fire, as an area of technical study in tall buildings, crosses over into many of the other assemblies, such as façades, materials, and structural types—mass timber for example.

Grenfell focused on the unfortunate misuse of a highly flammable cladding material, aluminum composite panels (ACPs), with a polyethylene core that continues to be an “accelerant” to façade fires to this day. The word “accelerant” is critical to this issue, as many buildings are opting to use a wide range of new materials and cladding types, instead of less-interesting traditional materials such as brick, stone and precast concrete, which are inherently non-combustible. It is problematic for the fire crew arriving on scene who are accustomed to the more traditional use of noncombustible materials such as concrete and masonry.

The current range of innovative façade materials has created a high degree of uncertainty that, in the case of

Grenfell, led to a continuation of a “shelter in place” directive from a fire department that was not expecting this type of fast-spreading façade fire.

At the CTBUH 2022 Conference in Chicago, the Fire and Systems joint workshop was tasked with considering how we might address the creation of a new CTBUH certification process for tall buildings.

In looking at this challenge, several things became immediately apparent that would present barriers to creating an internationally applicable system: ­Every country has different building and fire codes (some even vary within a country). ­Every country has different building practices (some may not be best practices). ­Fire-fighting equipment and practices vary around the world, and even within localities. ­Testing for fire is inconsistently carried out and applied to codes. ­Building risk varies by height, occupancy, layout, fire load, etc., and the determination of that risky height varies by jurisdiction. ­Some buildings are existing (to which old rules apply) and some new (better potential to craft new rules around). ­Renovated buildings pose uncertainty in the extent to which they can be upgraded for fire safety. Can risky façade replacement (the discussion that followed Grenfell) be mandated? ­Building risk varies by use. Should commercial, residential and mixed-use buildings have different requirements? Many of the ACP-related façade fires started on balconies, which are not as common on some building types.

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VINCENT EISFELD (CC BY-SA)

Figure 2— The Address, Dubai, was clad with aluminum panels; a 2015 fire within those panels was undetected by interior fire alarms.

Fire and Façades Although the discussion in the Sydney workshop seemed agreed upon the necessity of avoiding the application of flammable façade materials in future builds, this still varies by jurisdiction. Understandably, post-Grenfell, many architects and engineers were deeply concerned about the liability that had been created by perhaps unknowingly specifying the incorrect ACP on projects. Thankfully, many of the suppliers of the offending material withdrew it from production.

There was, however, no consensus whether or not ACP, which indeed provides many design advantages, including choice in color for projects, was still acceptable to use on low- to mid-rise buildings, where evacuation would be faster, and the majority of fire-fighting equipment would be able to reach the highest floors. This connects with the discussion of the measurement of a set maximum height above ground for its use, combined with the variation in the reach of fire-fighting equipment. It is quite the puzzle.

Grenfell also provided for continuing discussion as to best practices in undertaking recladding.

The driver behind the Grenfell renovation was to greatly increase the energy efficiency of the existing enclosure, as well as tart up its Brutalist exterior.

As the most sustainable building from an embodiedcarbon perspective is one that already exists, recladding as an approach is seeing increasing use.

We see the need for a better understanding and establishment of best practices, as there were design flaws in the detailing and choice of materials in the Grenfell façade. Most tall building designers well understand the need to fire-stop curtain124 Vertical Urbanism 4 II / 2025 RESEARCH

wall enclosures at each floor to prevent the spread of smoke and fire inside of the enclosure during an event.

However, in jurisdictions that are new to the design of rain screens, or vented insulated façade systems, it may not be readily apparent that these exterior cavities also require compartmentalization. In the case of Grenfell, the over-cladding of the concrete panels and columns created an air gap that ran continuously up the façade, allowing for the fire to chimney up the building exceedingly fast. The 150-mm of polyisocyanurate insulation in the cavity also fueled the fire. Best practices for fire safety in rain screen design would stipulate compartmentalization at each floor, as well as the use of non-combustible insulation in the cavity.

Other re-clad projects can be seen to use the application of a double façade comprised of a predominantly glazed outer layer in their upgrade.

Again, the continuity of the cavity must be examined and designed to prevent vertical fire spread.

Compartmentalization can work against the best functions of the double façade to form a buffer.

Often sprinklers will be used as a means of fire control, but a more comprehensive look at all factors is required on these fairly bespoke applications.

Openings in façades (including extract fans, windows and balconies) pose an additional means of fire spread. Several of the façade fires in the UAE are noted as starting on balconies. As cigarette smoking gets pushed to exterior spaces by green building certification, we are more likely to see balconies used for this purpose. That, coupled with under-watered planters that serve as ashtrays and storage for combustible goods, presents a great risk. Balcony extensions, on the other hand, are seen as an effective

FOREST SERVICE PHOTOGRAPHY (CC BY-SA)

Figure 3— Wind-driven fire devasted wide swathes of Greater Los Angeles in January 2025.

The implications of the disaster are still being studied.

means of physically separating windows between floors and preventing fire from skipping up the façade through open or broken windows, when constructed of non-combustible materials.

As many tall buildings now make extensive use of exterior decorative lighting, electrical shorts can also ignite exterior façade material. One of the problems associated with these exterior fires is that they normally will not trigger interior fire alarms. This was the case at The Address fire in Dubai on 31 December 2015 (see Figure 2). This problem can be remedied by the additional use of exterior fire sensors.

The remediation of existing buildings that have made extensive use of ACP with polyethylene cores needs to be addressed. Post-Grenfell, several other residential towers in the United Kingdom were evacuated and recladding undertaken, and seven years later, remediation work was still underway or yet to commence on thousands of blocks. This is an expensive and disruptive proposition and subsequently, fervor to undertake this radical a method has stalled. There have been discussions about partial replacement where a non-combustible cladding could be installed, in bands around the tower, thereby limiting the vertical spread of the fire, which would be a more economical approach.

Fire and Wind I will admit that this (long overdue) article was spurred by the Los Angeles fires in January 2025 (see Figure 3).

An Instagram user posted a very realistic and disturbing (fictional) image of downtown Los Angeles fully engulfed. Wind has been cited as one of the key spreading mechanisms of the LA fire, with the speed and force of these January Santa Ana winds noted as

unusually extreme. One of the main methods of fire containment is the creation of wide “barren” boundaries—historically implemented in forests, but now challenged as to effectiveness, and vertically as is suggested by banding and balcony projections, and horizontally through the clearing of vegetation, kindling and roadways.

When winds become extreme, how wide must these be? The devastation along the highway near Malibu illustrates that a significant roadway separated these buildings from a burning landscape, the width of which was insufficient. The question then, when fires reach urban areas (at the Wildland Urban Interface, or WUI) will pertain to the ability of the exterior of buildings to resist ignition from wind-blown burning embers which can spread several kilometers from the source fire. Looking at the (very limited) success stories in the Palisades, carefully consider the preventative fire design of the Getty Museum, which sits virtually untouched in a field of destruction.

It is an excellent example of exterior-based strategies, carefully maintained landscape and noncombustible cladding, and fine detailing of all external components, which also included the use of crushed stone on its roof to prevent ignition by embers and a high degree of maintenance.

Not much study has been conducted around tall buildings regarding the shape of towers and the impact of wind in fire spread. The impact of corner design on vortex shedding is much-studied, but not also with fire spread in mind. Examination of fire spread on The Torch in Dubai, which sustained fires three times between 2015 and 2019, would illustrate that it spread more quickly up the corners (see Figure 4).

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­At what height (number of stories) should a building have at least two means of vertical escape? ­How should those means of vertical escape be provided (i.e., elevators vs. stairs)? ­Does the building evacuation strategy (which may include “staying put”) affect the number and type of means of vertical escape? ­At what building height should the number of vertical escape provisions be further increased above at least 126 Vertical Urbanism 4 II / 2025 RESEARCH

Figure 4— The Torch, Dubai, caught fire three times between 2015 and 2019 .

SIANDONOVAN

Evacuation Another contentious issue raised by Grenfell is the use of a single stair for egress. There are very few countries in the world that still permit a single stair, the United Kingdom being one, although the statutory guidance is changing for some buildings. The majority of countries require at least two stairs (as a function of floor plate size, use and occupant numbers) and many have also banned scissor stairs from new builds, as the distance between entrances is deemed insufficient in a fire scenario.

However, evacuation remains a contentious aspect of discussions within the committee, as the solutions are seen to be more complex and nuanced than simply choosing the number of stairs. There is no guarantee that simply using a two-stair scenario will result in no losses, if other conditions are not also met. The theme of the Fire Safety Workshop held at the CTBUH 2024 Conference in London was evacuation. Some of the questions discussed were:

Figure 5— The Campanar residential complex in Valencia, Spain, burned in February 2024.

The fire jumped from one tower to another.

AGSPP (CC BY-SA)

The February 2024 Campanar tower fire in Valencia, Spain, is an example of rapid fire spread which then set fire to the adjacent tower, resulting in 10 fatalities (see Figure 5). With the proximity of tall buildings in urban locations that have made widespread use of flammable cladding, and where there have been multiple cladding fires, such as the Marina Bay area of Dubai, it warrants study.

When should building façades become equipped with an exterior sprinkler system? With climate change becoming more extreme, favorable wind conditions and hot, tinder-dry landscapes are becoming more common. Where proper landscaping practices in the Los Angeles area were already cognizant of the need to maintain a clearance around buildings, such is not necessarily the practice of all buildings in all locations, and it is not by itself adequate. Better design of the exterior of buildings in these geographies and maintenance becomes a critical ongoing concern along with water resources capacity. In some notable fires around the world, firefighting has been prevented due to lack of water.

The more extensive use of green façades has not been fully addressed, as these carry the potential for fire spread if they become dry or overgrown. Wind and burning embers will also have a disastrous impact on an ignited façade when it comes to fire spread.

This, and the increased use of timber on building exteriors are on our list for future study.

two? Or can stair width be used to accommodate occupancy numbers?

Where many aspects of tall building design are purely technical, evacuation begs a deeper study into human behavior. Panic and complacency can both play havoc on planned systems of evacuation. As our population ages, mobility issues will greatly impact evacuation.

New elevator designs are becoming fire-safe and a directed means to evacuate, but occupants may not know whether their elevator has been so upgraded, and may still be skeptical that it will work. We understand this, having lived through the historic use of unpressurized stairwells that have filled with smoke and led to a large number of deaths. How is an occupant to understand the difference? Some of the workshop questions posed were: ­Does “stay put” remain a viable escape strategy (noting the strategy does not require any person to remain in a building)? ­Do we expect a greater proportion of occupants to elect to evacuate from a building than was historically the case, especially given recent events? ­How do those occupants who are unable to use stairs leave the building? ­Is it reasonable to expect mobility-challenged people to remain when others are leaving? ­How are occupants who stay provided with adequate life safety provisions? ­How might altering the fire safety provisions in a building change the occupant decision to evacuate or not (e.g. installing building-wide detection and/or notification alert systems, installing sprinklers, providing evacuation lifts, etc.)? ­How might (further) engaging with occupants to understand the fire safety provisions of their building change their behavior?

Work is being done to better understand human behavior using computer modeling that shows promise of providing a framework to understand these unpredictable factors.

Firefighting As can be seen with Grenfell, “shelter in place” was ultimately not the correct directive from the fire-fighting perspective, and many lessons have been learned from that fire. Real-world firefighting experience needs to play into the decisions made in the design world.

Their knowledge is based on life-and-death encounters with the design decisions of others.

I watched a Toronto firefighter on our tour of Merdeka 118 in Kuala Lumpur open the riser shaft door to see if his forearm would fit easily. This is his normal test to see if there is sufficient space to feed a vertical hose up to a floor in need.

In some jurisdictions, the fire chief has significant say in the approval process regarding the fire

evacuation plan. In 2022, a 52-story residential tower in the Canary Wharf district in London was proposed that used a single stair and traditional elevators. The London Fire Brigade pushed back, and the tower was redesigned to include two sets of stairs. It is important to note that a full fire strategy includes much more than the provision of two stairs. It is critical that there be fire separation between the two stairwells to prevent a crossover fire. The size of the stairwell needs to be sufficient to accommodate evacuating occupants, as well as firefighters that may use the stairwell in their processes. The stairwell is used to extend hoses if other riser locations or cavities are not available.

New Causes of Interior Fires At the fire workshop at the CTBUH 2023 Conference in Singapore, we looked at the impact of lithium-ion batteries on fire propagation. These batteries are commonly used in electric vehicles. In residential buildings, occupants often bring their e-bikes into their apartments for safe keeping. As these are relatively new vehicles, existing buildings often do not provide safe storage.

Studies have shown a high level of tampering with these batteries to extend their use and resale.

Conversion kits are shown to have more fire risk than properly manufactured units. This has been cited as increasing the potential for fire. Some municipalities have banned e-bikes from being brought into their housing and subway systems, citing fire risks.

Electric car batteries also present a perceived higher risk of fire than gasoline-powered vehicles.

It is important, then, to design good firefighting access in garages, and in particular underground parking where sprinklers are advantageous. The Luton Airport car park fire in October 2023 brought home the need for well-designed resilient multi-story car parking with sprinklers, noting that this was started by a diesel car fire that spread rapidly to engulf most of the cars on the upper levels.

Bigger cars with composite fuel tanks and modern plastics need more space around them to prevent rapid fire spread. Existing building codes and standards are now often well behind vehicle developments.

You might have noticed more questions than answers in this article. As a committee we are still discussing and trying to come to a consensus of at least best practices. For the time being, it is our intention to bring these questions to the CTBUH membership, so that you might keep them in mind when considering your life safety strategies. We did pose one question in our Chicago workshop that did come up with a consensus answer. It was: What is the number of people that is acceptable to die in a fire?

A note of thanks to Gary Strong, Global Building Standards Director, RICS, for contributing to this article and for his leadership in chairing the Safety & Resilience Committee. He is stepping down from this role and his wisdom will be sorely missed.

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This study examines how irregular twin-tower skyscrapers influence local microclimates and energy demands in cold climates, using the Absolute World Towers in Mississauga as a case study. Computational fluid dynamics (CFD) and wind tunnel tests reveal that nonuniform towers increase rooftop wind speeds and convective heat loss in winter, potentially raising heating energy consumption. While their forms improve aerodynamics and aesthetics, these towers experience uneven solar heat gain and greater variability in energy demand.

The study suggests that such microclimate effects could be leveraged for renewable energy integration, offering opportunities for sustainable design adaptations.

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Authors: Varuni Jayasooriya, Matthew Adams Keywords: Cold Climates, Computational Fluid Dynamics (CFD), Heating Energy Demands, Irregular Twin-Towers, Microclimate Impact

influencing the corresponding energy demands in response to local climates.1,2 This paper compares a pair of non-uniform twin towers to equivalent uniform structures, using CFD simulations and wind tunnel experiments to assess differences in wind behavior, heat loss, and solar gain under winter conditions.

TERRI MEYER BOAKE

Figure 1— Twisting Architectural Form of Absolute Twin Towers, Mississauga.

1. INTRODUCTION In the domain of contemporary global high-rise building construction, there has been a prominent shift towards the designing of irregularly-shaped skyscrapers, aimed at elevating the visual aesthetics of urban environments. This architectural trend has now extended to include the construction of twin towers, ushering in a new era in skyscraper design.

It is widely acknowledged that high-rise buildings located within urban canyons have a notable impact on urban microclimates, influencing various ambient climatic factors such as air flow, velocity, heat distribution, moisture transport, and solar radiation.

These alterations in climatic conditions can significantly affect the thermal comfort experienced by residents residing at different heights and orientations within the buildings. In the case of adjacent buildings with non-uniform shapes, distinct variations in thermal comfort levels are expected in different weathers and times of the day, potentially

1.1 Non-Uniform Skyscraper Designs with Twisted Architecture The adoption of twisting in skyscraper design can be attributed to various factors, including performance considerations and aesthetic preferences. From a performance standpoint, twisting has been recognized as a highly efficient strategy for reducing wind-induced effects, thereby enhancing the overall resilience of tall buildings. By minimizing wind pressure on façades and mitigating building sway, twisting contributes to improved structural integrity and occupant safety.

Additionally, the dynamic and sculptural forms achieved through twisting appeal to architects and developers seeking to create iconic landmarks that resonate with the surrounding urban fabric.

While some skyscrapers incorporate twisting primarily for its functional benefits, others leverage it as a means of expressing architectural innovation and creativity.3 Recognizing this phenomenon, the Council on Tall Buildings and Urban Habitat (CTBUH) conducted a comprehensive analysis in 2016, examining 28 twisting towers worldwide, which investigated the average floor rotations and total rotations of these structures, revealing a remarkable diversity of textures, viewing angles, and ripple effects resulting from their unique geometries. Twisting towers have emerged as iconic landmarks, notable for their aesthetic appeal and, in many cases, their aerodynamic efficiency and energy-conscious design.4 From an aesthetic standpoint, the twisting geometries of tall buildings impart a sense of fluidity and modernity. However, the environmental implications of these designs are multifaceted and contingent upon factors such as climatic conditions and urban contexts. While some studies have demonstrated that twisting can mitigate wind loads, leading to potential savings in structural weight and costs, the broader environmental benefits remain less well-documented.3 2. BACKGROUND Canada’s extended and severe winters, a result of its considerable distance from the equator, necessitate substantially higher heating energy demands compared to cooling. Sub-zero temperatures are prevalent across the country during the winter months, with natural gas accounting for over 50% of heating energy supply in many Canadian cities.5 This reliance on natural gas significantly contributes to greenhouse gas (GHG) emissions during the winter season. Commercial, institutional, and residential combustion emissions in Canada increased by 3.8 Mt Vertical Urbanism 4 II / 2025 RESEARCH 129

Figure 2— Models of the towers simulated.

Air medium

Outlet

Inlet

Z Figure 3­­— The inlet and outlet specified for the external CFD analysis.

X

Z

Z

Tower A

Tower B

a) Model of the Non-Uniform Twin Towers

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X

X Tower A

Tower B

b) Model of the Uniform Twin Towers

(5.3%) from 2021–2022. This rise is consistent with a 6% increase in heating degree days, indicating that a colder winter and consequently a longer heating season were experienced in 2022.6 As Canada strives to achieve Net Zero Emission Goals by 2050, it is imperative to minimize the heating energy demands of buildings, particularly in cold regions. While research on high-rise buildings typically emphasizes structural integrity and general energy-related features such as materials and insulation, the long-term effects of the shape of overall building envelope on microclimatic variations— and consequently on heating energy demands— remain underexplored. This study investigates the impact of non-uniform, twisted twin tower designs, exemplified by the Absolute World Towers in Mississauga, Ontario, Canada, on surrounding microclimates and heating energy consumption.

Understanding how these architectural forms influence microclimates and heating requirements is crucial for developing energy-efficient high-rise buildings in cold climates. These insights are vital for designing sustainable high-rise built environments that address the higher heating demands necessary to maintain occupant comfort in cold regions.

2.1 Absolute World Towers, Mississauga The Absolute World Towers, prominently situated in Mississauga, Ontario, Canada, are a remarkable pair of high-rise buildings that have become iconic in the cityscape. Commonly referred to as the “Marilyn Monroe” buildings due to their distinctive curvaceous design, these towers epitomize architectural ingenuity and aesthetic appeal. Completed in 2012, the Absolute World Towers consist of two residential skyscrapers, one 175.8 m high (60 Absolute World, 56 stories) and the other standing at 157.8 m height (50 Absolute World, 50 stories).

The towers are also known as Mississauga’s tallest and second-tallest skyscrapers.7,8 What sets these structures apart is their non-uniform, sculptural forms that elegantly twist and turn, creating an enchanting visual effect (see Figure 1).

Absolute Towers represent a notable instance where the twisting design exhibited a more organic, less regimented form, resulting in a fluid spatial volume, particularly accentuated by the integration of smooth slabs and balconies. Beyond its distinctive aesthetic, the incorporation of balconies is planned to serve a dual purpose, enhancing both energy performance and resident comfort. However, despite the acknowledged benefits, quantitative assessments regarding the energy-saving potential have yet to be provided. Specifically, a colder country like Canada could benefit from the availability of such data to evaluate heating energy demands when designing such non-uniform twin towers.

In terms of the broader scientific domain, previous research has explored the variations in microclimates among tall buildings using hypothetical building

designs.2,9 Nevertheless, to the best of the authors’ knowledge, no studies have been identified in the literature that specifically investigate the relationship between thermal comfort and heating energy demands in a real-world scenario of non-uniformly-shaped twin towers located in colder climates. This research aims to bridge this gap by providing empirical insights into the microclimate and heating energy demand dynamics of such twin towers in cold weather conditions.

Specifically, the research will evaluate the impact of these non-uniform, paired sculptural forms on the microclimate within and around the buildings, investigate how the twisted design affects heat dissipation to the surroundings during the Canadian winter season, and contribute to the understanding of non-uniform twin tower design in colder regions, focusing on microclimatic conditions and heating energy demands.

3. RESEARCH DESIGN 3.1 Computational Fluid Dynamics (CFD) Modeling The analysis focuses on the twisting Absolute Towers, situated adjacent to each other, selected as the study subjects. For research purposes, these towers are treated as standalone structures, disregarding the influence of surrounding buildings, to isolate the impact of their unique shapes. Computational fluid dynamics (CFD) simulations are conducted to analyze the thermal behavior of the buildings during the coldest winter months in Canada: December, January, and February. Boundary conditions were established using the average wind speed and wind direction to represent typical local winter conditions in the region.

ANSYS Fluent 2024 R1 was employed to simulate the dynamics of the high-rise towers, due to its ability to effectively handle the complex surface geometry presented in the Absolute Towers.

To compare the results and evaluate the effect of building shape, a control simulation is performed on two buildings with similar dimensions, but without the twisting characteristic present in the Absolute World Towers. The comparative analysis allows for the assessment of how the non-uniform twisting shape in the building design influences heating energy demand. Figure 2 shows the geometries of the Absolute World Towers with non-uniform shape and the control geometry of uniformly-shaped twin towers, which were compared in this study.

Henceforth, when discussing the towers, the shorter of the two will be designated as Tower A, while the taller one will be denoted as Tower B. The simulation is conducted with an average air velocity of 4.6 m/s (based on the average wind speed value for the coldest months December, January, and February), with airflow introduced through the inlet as shown in Figure 3, resulting in velocity and pressure contours close to the building walls.

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Figure 4— Sample simplified geometry and zone naming conversion allocated for each floor (i.e.: Absolute Tower A with 56 floors).

Top Roof

Z1 Z2 Z3 Z4 Z5

Outer Surface Inner Surface

...Z56

3.2 Analyzing the Heat Gain and Heat Losses To analyze heat loss between the buildings, an external CFD setup is utilized, with adjustments made to air and internal zone temperatures to 26°C respectively, while maintaining an air velocity of 4.6 m/s (Average air velocity during colder months for the location as per NERL, 2023 11).10 This configuration facilitates quantifying the heat exchange between the buildings and the surrounding air. Figure 4 shows the building configuration, with zones delineated with a naming conversion, representing letter “Z” and floor ID, from top to bottom, where the outer surface functions as shading or balcony, and the inner surface as window or glazing. In high-rise buildings, inlets and outlets are strategically positioned openings designed to supply either hot or cold air, facilitating proper ventilation and thermal control within the building.

These ventilation systems serve crucial roles in maintaining indoor air quality, thermal comfort, and energy efficiency. Inlets typically allow for the intake

132 Vertical Urbanism 4 II / 2025 RESEARCH

of fresh air into the building, while outlets facilitate the expulsion of stale air and pollutants. Two inlets and outlets are incorporated to supply hot or cold air for the studied high-rise buildings, as represented in Figure 5. For solar heat gain analysis, the air velocity from the inlets is disregarded, focusing solely on solar heat gain. Both inner and outer surfaces are attributed materials: glass and concrete, justified by the prevalent construction practices in the study area favoring high-thermal-capacity concrete, leading to elevated outer surface temperatures and increased absorption of solar radiation due to multiple reflections between buildings. These material choices significantly influence the energy loads of the buildings and contribute to the urban thermal balance and urban heat island phenomena.

3.3 Wind Tunnel Experiments and Analysis The final phase of this research involved a wind tunnel experiment to comparatively investigate heat dissipation from uniform and non-uniform twin tower designs. Wind tunnel experimental analysis aimed to complement CFD simulation results by considering atmospheric boundary layer conditions.

Two 3D models of the twin towers, scaled 1:400, were prepared with uniform and non-uniform designs.

Twelve thermocouples were attached to each model at various heights to measure heat loss. Additionally, resistance temperature detector (RTD) probes were used to measure ambient temperatures upstream and downstream of the buildings. Figure 6 shows the various stages of the experimental setups for uniform and non-uniform twin towers.

Figure 5— Defined air supply inlets and outlets for the buildings.

Figure 6— Setting up the wind tunnel experiments: a) Resin-based 3D printed models for uniform and non-uniform twin tower; b) The openings of the models to fill water; c) Setup of thermocouple

sensors in non-uniform twin towers; d) Setup of thermocouple sensors in uniform twin towers; e) Final wind tunnel experiment setup with the temperature and wind velocity probes.

Inlets

Inlets

Outlets

Outlets

The models were made of water-resistant materials and filled with high-temperature water to simulate heat dissipation in each simulation run. The initial temperatures of the thermocouples were taken, and each wind tunnel experiment was run for two minutes until the heat dissipation became stable. The wind tunnel experiments were performed at the Wind Engineering, Energy, and Environment (WindEEE) Dome at Western University, a hexagonal wind chamber that has the capacity to modify the wind patterns and change their direction during a simulation.12 The test performed at the WindEEE Dome utilized standard wind tunnel methods to create atmospheric boundary layer (ABL) flows representative of the subject location.

Two ABL profiles were tested following Engineering Science Data Unit 13 Standard 82026’s Table 13.1 Values of Surface Roughness Parameter, zo. Flows with surface roughness terrain descriptions “Large expanse of water” and “Suburbs” were generated through utilization of a specific combination of the WindEEE Dome’s roughness elements, trip, and spires, thus testing for both “smooth” and “turbulent” flows. To replicate the winter conditions in the study area, the wind tunnel assessment focused on two prominent wind directions: 250° and 270°, with 0° serving as the baseline. To maintain accuracy and reliability, three replicates were performed for each experimental set. The above specific test cases were applied during the experiments and the following equation was used to calculate the normalized percentage heat loss in two experimental setups during various wind profiles.

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Figure 7— Velocity contours at 4.6 m/s avg. wind velocity for the colder months.

Velocity Contour 1

Velocity Contour 1

8.539 8.085 7.591 7.116 6.642 6.167 5.693 5.219 4.744 4.270 3.795 3.321 2.846 2.372 1.898 1.423 0.949 0.474 0.000

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6.847 6.466 6.086 5.705 5.325 4.945 4.564 4.184 3.804 3.423 3.043 2.663 2.282 1.902 1.521 1.141 0.761 0.380 0.000

Velocity Contour 1 8.275 7.815 7.355 6.895 6.436 5.973 5.516 5.057 4.597 4.137 3.678 3.218 2.758 2.298 1.839 1.379 0.919 0.460 0.000

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Figure 8— Pressure contours at 4.6 m/s avg. wind velocity for the colder months.

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15.391 12.234 9.078 5.921 2.764 -0.393 -3.549 -6.706 -9.863 -13.020 -16.176 -19.333 -22.490 -25.647 -28.803 -31.960 -35.117 -38.274 -41.430

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Pressure Contour 1

10.488 8.628 6.768 4.907 3.047 1.186 -0.674 -2.534 -4.395 -6.255 -8.116 -9.976 -11.836 -13.697 -15.557 -17.418 -19.278 -21.138 -22.999

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Non-Uniform Twin Towers Temperature Contour 2 10.671 10.450 10.228 10.006 9.784 9.562 9.340 9.118 8.897 8.675 8.453 8.231 8.009 7.787 7.565 7.344 7.122 6.900 6.678 [Pa]

Uniform Twin Towers Temperature Contour 1 12.001 11.706 11.412 11.117 10.822 10.527 10.233 9.938 9.643 9.349 9.054 8.759 8.464 8.170 7.875 7.580 7.286 6.991 6.696 [Pa]

Figure 9— Surrounding temperature distribution due to air flow between the buildings (uniform and non-uniform twin towers).

4. RESULTS AND DISCUSSION 4.1 CFD Analysis The post-processing analysis reveals the external air patterns for the two clusters of non-uniform twin towers and uniform twin towers. Contours are generated along three distinct planes to visualize air intensity as follows: Plane 1—Positioned on the top of Tower A. Plane 2—Positioned on the top of Tower B. Plane 3 —Positioned between the two buildings (To provide insights into the airflow interaction in interstitial space).

Figures 7 and 8 indicate the variations of wind velocity (velocity contours were assessed at 4.6 m/s-1 based on the monthly means for the months December, January, and February for the study area) and the pressure along the selected planes respectively.

Area A1, delineated in Figure 7 (a), exhibits a peak air velocity of approximately 8.6 m/s within the space bound by the two buildings. Concurrently, Figure 8 (a) shows the presence of negative pressure in this region, which contributes to an escalation in air velocity within the area. Similarly, the area A2 within the uniformly-shaped twin towers shows an approximate velocity of 7.5 m/s.

A mere 1 m/s difference in outdoor air velocity can significantly influence both the microclimate and energy efficiency of a building.14 In terms of the microclimate surrounding these buildings, higher

outdoor air velocity can affect the microclimate around the building, potentially leading to increased wind exposure and wind-driven heat transfer.

Increased air movement can enhance natural ventilation, promoting airflow around the building and reducing the risk of stagnant air pockets. However, it should also be noted that this phenomenon would be desirable during warmer weather for enhanced thermal comfort. In addition, higher wind speeds can also lead to increased infiltration of outdoor air into the building, potentially causing drafts and discomfort for occupants, particularly near windows and doors facing the wind direction. Higher outdoor air velocities can impact the energy efficiency of a building by increasing the convective heat transfer between the building envelope and the surrounding air. Therefore, during colder periods, higher wind speeds can lead to increased heat loss from the building, resulting in higher heating demands and reduced energy efficiency.

Conversely, during warmer periods, higher outdoor air velocities can enhance natural ventilation, reducing the need for mechanical cooling and improving energy efficiency by decreasing reliance on air conditioning systems.

4.2 Heat Gain and Heat Loss Analysis The analysis of solar gain and heat loss plays a fundamental role in achieving energy efficiency in building designs. Variations in air turbulence observed from previous CFD analyses can significantly influence the dynamics of heat gain and loss in both uniform and non-uniform twin towers. The subsequent findings presented here offer a comparative Vertical Urbanism 4 II / 2025 RESEARCH 135

Non-Uniform Twin Towers Y

Temperature Contour 1 28.226 27.043 25.859 24.676 23.493 22.310 21.127 19.943 18.760 17.577 16.394 15.211 14.028 12.844 11.661 10.478 9.295 8.112 6.928 [C]

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Z X

Temperature Contour 1 28.822 27.605 26.388 25.171 23.953 22.736 21.519 20.302 19.085 17.867 16.650 15.433 14.216 12.999 11.781 10.564 9.347 8.130 6.913 [C]

Tower A

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Figure 10— Temperature gain comparison between uniform twin towers A and B (left) and non-uniform towers A and B (right).

analysis of heat gain and loss for these two design typologies. Figure 9 shows the comparison of the surrounding temperature distribution attributed to the heat loss due to the wind dynamics between the two twin tower designs.

Based on the CFD findings, it is evident that non-uniform twin towers experience intensified heat loss compared to their uniform counterparts, a characteristic that may pose challenges in colder climates for the twisted tower design examined in this study. This heightened heat loss could lead to occupant discomfort during winter months, accelerating the need for interior heating and potentially increasing overall energy demand. Conversely, this thermal behavior may confer an advantage during warmer seasons, facilitating quicker heat dissipation and cooler indoor temperatures, thus reducing the need for air conditioning. However, it is important to note that these conclusions are context-dependent, varying based on factors such as the specific shape, orientation, and local climate conditions of the non-uniform towers under consideration. What is of paramount importance is the careful consideration of wind flow dynamics between such unique shapes and designs with twin-tower high-rise buildings, particularly in cold climates like those investigated in this study, to ensure optimal heating energy efficiency in the long-term building operational stage.

4.2.2 Solar Heat Gain Analysis Solar heat gain analysis typically involves assessing how much solar radiation reaches different surfaces 136 Vertical Urbanism 4 II / 2025 RESEARCH

Z Y

of a building throughout the day and across different seasons. The Energy Plus Weather (EPW) file for the Toronto Pearson International Airport (ID716240) was used to obtain solar radiation data, including direct normal irradiance (DNI), diffuse horizontal irradiance (DHI), and global horizontal irradiance (GHI), which are essential inputs for calculating solar heat gain. Results obtained for the temperature gain comparison of the two buildings are shown in Figure 10.

Tower A, positioned to face the sun, partially obstructs solar heat gain for Tower B. It is important to highlight that each floor within these buildings was treated as a singular zone for this study, with results presented accordingly. However, assessing temperature gains within individual units based on their floor plans falls beyond the scope of this research. Figures 11 and 12 show the summary results obtained for each of the zones in terms of solar heat gain and the receiving heat flux based on the location. Notably, the zones identified as high gainers span from levels 27 to 47 in NonUniform Tower A. This pattern emerges due to the pronounced curvature of the building’s central section, which faces the sun most directly.

Consequently, heat dispersal in this area is notably more pronounced compared to other zones. This phenomenon aligns with existing research indicating that curved buildings exhibit a higher capacity for heat absorption than their simpler counterparts.

Such architectural designs are typically advantageous for heating purposes during the winter season.

X

Figure 11 (Below, left and right)— Solar heat gain comparison during the winter for various zones of uniform and non-uniform twin towers.

Figure 12 (Bottom, left and right)— Relationships between solar heat flux received and temperature gain during the winter for various zones of uniform and non-uniform twin towers.

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However, it is crucial to note that excessively high curvature may result in uneven distribution of solar heat across the building envelope, which can lead to localized overheating in certain areas and uneven temperature distribution within the interior spaces. In addition, increased horizontal curvatures may require increasing heating loads due to the presence of self-shading on walls of the building façade.15 In addition, when analyzing the heat gain of the various building zones, it can be observed that the temperature difference in various zones of these two different buildings only shows a slight difference between 1–2°C. However, it should be noted that a slight variation of 1°C can make significant change in the perceived human thermal comfort and can lead to variations in building heating or cooling energy demands.16 4.3 Wind Tunnel Experiments Using the formula presented in Section 3.3, the percentage change in temperature relative to the starting temperature of the façade was calculated.

The results obtained for both uniform and nonuniform twin towers for profiles of 0°, 250°, and 270° are shown in Figures 13, 14, and 15, respectively.

According to the results obtained from wind tunnel experiments, in the uniform twin towers, heat dissipation patterns across the sensors demonstrate a consistent and gradual decline over time. Initially, the percentage of heat dissipation is relatively high, with all sensors recording values between 45% and 55%. Over time, there is a steady and uniform reduction in these percentages, reflecting a predictable pattern of heat loss. For example, as illustrated in Figure 13, sensors 01, 05, and 07 maintain mid-range dissipation levels, commencing around 50–55% and exhibiting a gradual decrease. Sensor 09 starts at a slightly lower value of 50% but ends at a lower percentage compared to other sensors, suggesting a higher overall rate of heat dissipation. Notably, Sensor 12 experiences the most pronounced drop, starting at approximately 45% and declining to below 30% by the conclusion of the observation period, indicating the highest rate of heat loss among all sensors. Conversely, the non-uniform twin towers display a more heterogeneous heat dissipation trend compared to their uniform counterparts.

While a general decline in heat dissipation over time is observed, the rates of decline and initial dissipation

138 Vertical Urbanism 4 II / 2025 RESEARCH

percentages exhibit greater variability. This variability suggests a more complex thermal dynamic system within the non-uniform structure. For instance, as shown in Figure 13, Sensor 01 starts between 55–60% and experiences a significant initial drop before stabilizing at a mid-range level. Sensors 05 and 07, like the uniform scenario, show closely aligned dissipation patterns, beginning around 55% and demonstrating steady declines. Sensor 09 again exhibits a notable drop, ending at a lower level than most sensors, while Sensor 12 shows the steepest decline, starting above 45% and falling below 30%, indicating the highest rate of heat dissipation in the non-uniform configuration.

The observed heat dissipation trends have important implications for heating energy demand, particularly during colder periods. In uniform twin towers, the consistent and predictable decline in heat dissipation across all sensors suggests a uniform rate of heat loss throughout the structure. This steady dissipation implies that uniform twin towers may require a consistent, yet potentially lower, heating energy input to maintain comfortable indoor temperatures. The uniformity in heat loss facilitates more efficient and predictable heating system operation, optimizing energy use and minimizing waste. In contrast, the non-uniform twin towers exhibit significant variability in heat dissipation rates among sensors, indicating that different areas of the building lose heat at varying rates. This variability can lead to uneven indoor temperatures, necessitating more complex and potentially higher heating energy inputs to ensure comfort throughout the building.

Consequently, the non-uniform heat dissipation pattern may require more adaptive and energyintensive heating solutions to address the uneven thermal performance.

In summary, even a small difference in outdoor air velocity can influence the microclimate around a building and impact its energy efficiency. While higher wind speeds can enhance natural ventilation and reduce the cooling load during warmer periods, they can also increase heat loss during colder periods and cause discomfort for occupants. Therefore, it’s important to consider outdoor air velocity in building design and energy management strategies to optimize both microclimate conditions and energy efficiency.

When comparing the two configurations, it is evident that the uniform twin towers maintain a more consistent and predictable heat dissipation pattern.

The uniformity in structure appears to contribute to a steadier rate of thermal decline across all sensors, with less fluctuation observed between them.

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Figure 13— Heat dissipation during the 00 wind profile

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Figure 14— Heat dissipation during the 2500 wind profile.

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Figure 15— Heat dissipation 60 the 2700 during wind profile.

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This consistency could imply more efficient thermal management in uniform structures, potentially leading to better performance and structural integrity over time. In contrast, the non-uniform twin towers exhibit greater variability in heat dissipation. The wider range of starting percentages and varied rates of decline among the sensors suggest that non-uniform structures may experience more complex and less predictable thermal dynamics. This variability could pose challenges in managing heat dissipation effectively, potentially impacting the overall performance and longevity of the structure.

5. CONCLUSION AND RECOMMENDATIONS The study highlights significant differences in heat dissipation trends between uniform and non-uniform twisted twin tower configurations due to convective heat transfers and surrounding microclimate variations.

Uniform twin towers exhibit a more predictable and consistent pattern of heat loss, suggesting better thermal performance and management. Non-uniform twin towers, while showing greater variability, highlight the need for more sophisticated thermal management strategies to address the complex heat dissipation dynamics. These insights are crucial for the design and engineering of high-rise twin tower structures, emphasizing the importance of structural uniformity in thermal performance assessments. Additionally, the implications for heating energy demand during winter underscore the potential for lower energy consumption in uniform structures, contributing to more efficient and cost-effective building management in colder climates.

As the outcomes of the wind tunnel experiments suggest, understanding heat dissipation trends in different structural configurations is crucial for assessing heating energy demands, especially during winter or cold periods. The comparative heat dissipation insights between uniform and non-uniform twin towers highlighted significant implications for heating energy requirements during colder months. In addition, the findings of this study reveal that the unique non-uniform twin tower twisted skyscrapers investigated herein present both distinct advantages and disadvantages in energy demand when compared to uniform-shaped designs

142 Vertical Urbanism 4 II / 2025 RESEARCH

of equivalent dimensions. Understanding the magnitudes of these advantages and disadvantages is crucial for comprehensively evaluating the overall energy demand benefits of such structures over the course of a year (considering both heating and cooling energy demands). However, our study focused specifically on how these different building designs can influence heating energy demands during the colder winter seasons in Canada. Based on the CFD results obtained, it shows that non-uniform twin towers may experience an increase in heating energy demand compared to uniform twin towers. This increase can be attributed to alterations in windrelated microclimatic conditions around the building surroundings induced by the unique shape of the towers. Nevertheless, it’s worth noting that these same microclimatic conditions could potentially offer opportunities to offset the higher heating energy demands through the integration of renewable energy sources, such as wind power. This could involve the incorporation of local-scale building-integrated wind turbines, particularly suitable for colder climates with significantly higher wind velocities present in regions such as Canada. Given that many regions in Canada rely heavily on non-renewable energy sources with a high carbon footprint for heating energy generation, exploring such renewable energy solutions is paramount for reaching global interventions such as NetZero 2050 goals. Therefore, further research and development in this area are recommended on incorporating building-integrated wind turbines, particularly, when considering the construction of uniquely designed iconic high rise building design in the future.

Furthermore, it should also be noted that the results presented are specific to the case study considered and may vary due to factors such as local climatic conditions and the design of the twin tower’s external envelope. Often overlooked in high-rise design, the assessment of building-envelope-induced microclimate conditions on their overall energy demands are crucial, particularly with the current trend towards uniquely shaped buildings for aesthetic purposes. Therefore, the present study highlights why such factors should warrant careful consideration during the design phase of future iconic twin tower skyscrapers.

Acknowledgements The authors extend their deepest gratitude to the Council on Tall Buildings and Urban Habitat (CTBUH) International Seed Funding Program 2023, kindly sponsored by Sun Hung Kai Properties, for generously supporting this research. We also sincerely thank the team at the Wind Engineering, Energy, and Environment Research Institute (WindEEE RI) at Western University, especially Girma Bitsuamlak, Professor and Director of WindEEE RI, with Adrian Costache, Tristan Cormier, and Kimberly Adamek, for their invaluable contributions to the wind tunnel experiments, experimental design, planning, and 3D modeling.

Credits— Unless otherwise noted, all images and graphics are courtesy of the authors.

NOTES 1 Mirrahimi, Seyedehzahra, Mohd Farid Mohamed, Lim Chin Haw, Nik Lukman Nik Ibrahim, Wardah Fatimah Mohammad Yusoff, and Ardalan Aflaki. (2016). “The Effect of Building Envelope on The Thermal Comfort and Energy Saving for High-Rise Buildings in Hot–Humid Climate.” Renewable and Sustainable Energy Reviews 53: 1508–19. https://doi.org/10.1016/j.rser.2015.09.055.

2 Meena, Rahul Kumar, Ritu Raj, and S. Anbukumar.

(2022). “Effect of Wind Load on Irregular Shape Tall Buildings Having Different Corner Configuration.”

Sādhanā 47. https://doi.org/10.1007/s12046-022-01895-2.

3 Jakica, Nebojsa and Mikkel K Kragh (2020). “Assessing Self-shading Benefits of Twisting Towers.” Journal of Façade Design and Engineering 8(1): 115–30.

4 Council on Tall Buildings and Urban Habitat (CTBUH).

(2016). “Twisting Tall Buildings.” CTBUH Journal 2016 Issue III: 46–7.

5 Statistics Canada. (2023). “The Heat is on: How Canadians Heat Their Home During the Winter.” https:// www.statcan.gc.ca/o1/en/plus/2717-heat-howcanadians-heat-their-home-during-winter.

6 Environment and Climate Change Canada (ECCC).

“Greenhouse Gas Sources and Sinks in Canada: Executive Summary 2024.” https://www.canada.ca/en/ environment-climate-change/services/climate-change/ greenhouse-gas-emissions/sources-sinks-executivesummary-2024.html.

7 Frearson, Amy. (2012). “Absolute Towers by MAD.” Accessed: 5 February 2024. https://www.dezeen. com/2012/12/12/absolute-towers-by-mad/.

8 Lagendijk, Bas, Anthony Pignetti, and Sergio Vacilotto.

(2012). “Shapely Pair of Towers Challenges the Status Quo.” CTBUH Journal 2012 issue IV: 12–7.

9 Ming, Gu, Peng Huang, Lin Tao, Xuanyi Zhou, and Zhong Fan. (2010). “Experimental Study on Wind Loading on A Complicated Group-Tower.” Journal of Fluids and Structures 26(7–8): 1142–54. https://doi.org/10.1016/j. jfluidstructs.2010.08.003.

10 RBHF. (2024). “What is the Legal Temperature for Tenants in Ontario.” https://www.rbhf.ca/2021/05/ what-is-the-legal-temperature-for-tenants-in-ontario/.

11 National Renewable Energy Laboratory (NREL). (2023).

“TMY3 Weather Data for Mississauga, Ontario, Canada [EPW file]. EnergyPlus Weather Data (EPW) Collection.” https://energyplus.net/weather-location/north_america_ canada/ONT/Mississauga_City.ONT_CWEC.epw.

12 Renaud, Jeff. (2022). “Sustaining WindEEE’s Excellence Entails Digital Transformation.” Western News. https:// news.westernu.ca/2022/11/digital-windeee/.

13 Engineering Sciences Data Unit (ESDU). (2003). “ESDU 82026: Strong Winds in the Atmospheric Boundary Layer.”

ESDU. 14 Jang, Gukhwa, Saehoon Kim, and Jae Seung Lee. (2022). “Planning Scenarios and Microclimatic Effects: The Case of High-Density Riverside Residential Districts in Seoul, South Korea.” Building and Environment 223. https:// doi.org/10.1016/j.buildenv.2022.109517.

15 Raof, Binaee Yaseen. (2017). “The Correlation Between Building Shape and Building Energy Performance.”

International Journal of Advanced Research (IJAR) 5(5): 552–61. https://dx.doi.org/10.21474/IJAR01/4145.

16 Schweiker, Marcel, Gesche M. Huebner, Boris R. M. Kingma, Rick Kramer, and Hannah Pallubinsky. (2018).

“Drivers of Diversity in Human Thermal Perception–A Review for Holistic Comfort Models.” Temperature 5(4): 308-342.

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Right— Jeddah Tower, 1,000+ meters, has resumed construction after a sevenyear pause and is projected to complete in 2030.

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For an interactive version of this CTBUH data study, scan the QR code below

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Of the region’s 563 buildings over 150 m in height (150 m+), half have been completed since 2012—and CTBUH is tracking a further 71 currently under construction.

This data study—by CTBUH Research & Thought Leadership—examines the region’s developments and trends. For more in-depth analysis of these trends, look for the 2025 edition of the CTBUH Data Handbook in September 2025.

ADRIAN SMITH + GORDON GILL ARCHITECTURE

Across the Middle East and Africa, urban development continues to grow at an unprecedented pace. Dubai, the most established highrise hub in the region, is undergoing another surge in tall building development.

Ambitious mega-projects in Egypt and Saudi Arabia are bringing a similar energy to those regions, while developing countries in Africa compete to complete their next tallest buildings.

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5,655 Douala

6,228

6,595 Addis Abababa

Mashhad

6,679

6,913 Antananarivo

Cairo

6,915 Yaounde

7,831 Kinshasa

8,487 Alexandria

Mogadishu

9,799

Khartoum

0 / km2

5,000 / km2

10,000 / km2

Density

Vertical Urbanism 4 II / 2025 RESEARCH 145

From Rome to New York, Steven Holl traces the subtle forces—sunlight, memory, movement —that shape his building designs.

“What is there more mysterious than clarity?”

—Eupalinos, Paul Valéry Today, working with doubt is unavoidable—the absolute is suspended by relatives and the interactive. Instead of stable systems, we must work with dynamic, changing systems (just as we must work with changing climate). Instead of simple, fixed programs, we engage contingent and diverse ones. These challenges yield new opportunities to mix urban programs—a new vitality of hybrid architecture that shapes and enriches the spaces of cities.

We are drawn to an architecture that integrates landscape and space-shaping urbanism—one grounded in site, culture, and climate rather than an applied signature style.

Openness to uncertainty can yield works attuned to multiple contexts and conditions: not one urbanism, but many.

The experiential and phenomenal power of cities cannot be completely rationalized and must be studied subjectively. Few urban planners speak of the important phenomenological characteristics determining the qualities of urban life—spatial energy and mystery, qualities of light, sound, and smell. These phenomena are unique to each city.

The horizontal aspect of sunlight in cities like Helsinki (at 60° north latitude) gives special

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Above— Steven Holl’s Kiasma Museum in Helsinki, captures the city’s low, horizontal sunlight at 60° north.

Right— After a fresh rain, Rome’s shiny paving stones reflect light with a particular magic.

character and qualities to the urban spaces. (For example, the Kiasma Museum in Helsinki has a cupped intertwining geometry catching the low sun angle.).

Alternatively, think of the light and air of cities at 34° latitude.

The altitude and bearing angle of the sun, together with the number of rainy days per year and the mean temperature, does not yield an accurate description of place. Think of moving in rapid succession during the first weeks of summer from Rome to Barcelona to Madrid to Lisbon.

The astonishingly unique qualities of place in each of those cities is a wonder.

Rome in late June has a dry heat, sometimes fanned with the breeze of the Aviernos.

The huge scale of the Roman monuments packed into the ochre walls shapes the sky in slices and wedges in a way that alters the light. Light defines the urban walls and façades in a particular Roman way. Shiny black paving stones smoothly join the bottom of each façade. After a fresh rain, the streets of Rome have a particular magic in their reflections.

While Rome is the “eternal city,” Barcelona turns rapidly in time. The beveled blocks of the Cedra grid whirl like a clock.

They turn and turn again at corner

S HOLL

Where Architecture Begins

FINNISH NATIONAL GALLERY

INSPIRATION

S HOLL

Above — Renfro’s sketch of One World Trade Center reimagined as building typology for radical mixed-use.

crossings, repeated over and over across the main urban geometry.

The small, old, crooked-street city is surrounded by this modern whirling machine.

The polished marble pavement of the Ramblas glows with reflections of pedestrians walking past stands selling cats, live snakes, roosters, and parrots turning somersaults in their cafés. Barcelona has a sense of surrealist humor— very particular. Walking past the Portaferrisa shop windows, we see pads for shoulders, buttocks, groins, hips, and breasts proudly displayed on bright red felt backdrops. A dark humor particular to this city seen in adjacent shop windows.

The up-and-down urbanity of Lisbon’s cobblestone streets yields Tagus River and ocean vistas. Yet, the melancholy spirit of Fado music puts a serious spin on its sunny Mediterranean climate mood. As one of the oldest European cities, it nevertheless has an optimistic modern spirit —for example, in the luminosity of the Vasco da Gama bridge.

It’s a city of stone courtyards and mysterious inner fountains and the stories and poems of Fernando Pessoa (1888–1935), who wrote his own guidebook to Lisbon.

In great contrast, New York City’s Times Square demonstrates how vast quantities of artificial urban night light alter our perception of urban space. This

Above— At night, Times Square in New York City is defined by artificial light and reflections, transforming its urban character.

dirty, gray, crowded intersection by day is an astonishing volume of glowing light at night: space is defined by the interrelation of light, color, and atmospheric conditions.

In a slight mist, space is liquid.

Dynamic color reflected in wet streets blurs and multiplies the exhilaration of this metropolitan space in intense, cinematic levels.

When thinking of these urban experiences—the extreme contrasts of Helsinki, Rome, Barcelona, Lisbon, New York—working with doubt is unavoidable.

However, a clear concept, a clear idea to drive each unique design must be patiently discovered, no matter how long it takes, and more than anything, fine architecture takes time.

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ARCHIVE Evolving Habitats From student dream to global prototype, Moshe Safdie shares his drawings archive, alongside a 1970 text on living at Habitat 67.

I had never lived in a house before.

Habitat was the first. It was what I always imagined living in a house could be—and yet it wasn’t a house as we know it.

There were things happening around us all the time. We lived the way one might in a big house in a fancy suburb, and yet we also did things only possible in an apartment on, say, Sherbrooke Street in downtown Montreal or Fifth Avenue in New York.

We had both.

The wonderful thing about living in Habitat during Expo 67 was that it was exactly the way I envisioned it to be: a community, almost rural in nature, in the city.

People were around you in great numbers—not only those who lived there, but also the many visitors to Expo.

There were shops, movie theaters, exhibits, parks, and fountains. Ships docked in front, bringing people to visit the city.

All the elements that make a good city were there. And yet, with all those millions of people, when you closed the door, you were in your own house. You had privacy.

You really were alone.

You looked out at the view and were not aware of the crowds, even though they were there by the millions. You had a feeling of seclusion, of quiet. Never, in all the months I lived there, did I hear a neighbor through the walls or floors.

We would wake up in the morning and open the sliding doors to have breakfast in the garden. Our children opened the front door, got on their tricycles, and rode down the pedestrian street to the playground. They met other kids, made friends, and played half the day there and throughout the structure beyond our house. We had a dog and could take him for a long walk right outside our door.

These things, I suppose, would have been possible if we had lived on a quiet residential street in a suburb like Westmount, with our own house and garden. We could have had breakfast outdoors, and so on. There was nothing inherently unique about that— except that we were on the 10th floor, in an environment with 10 times the density of Westmount.

But in Westmount, if you wanted to see a film, go to the

Left— Moshe Safdie photgraphed on site at Habitat 67 during construction.

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Left— A duplex apartment at Habitat 67 photographed shortly after its completion.

library, or even get to work, you’d have to get in your car or take the bus or subway.

In Habitat during Expo, you went down 10 floors and found yourself among 50,000 people.

You could see the best movies, board a visiting ship docked nearby and join a party, or eat at one of dozens of good restaurants.

That mixture—of being in the busiest, most crowded urban meeting place and, at the same time, just a hundred feet away, closing a door and being alone in your house—was an incredible experience.

This sense of seclusion was achieved by the fact that the houses were free in space.

They all opened in three or four directions. From some windows, you saw the city; from others, the river or Expo. You had morning sun in some rooms, evening sun in others, and you felt the sun move around you all day.

Everything about it gave me the feeling of living in a house.

And yet it gave me all the other habitat-67_012.jpg things I had always wanted in a house but never found in the isolation of the anonymous suburb.

habitat-67_015.jpg

Left and right— Photographs of apartment interiors at Habitat 67, with views out onto private terraces. habitat-67_006.jpg

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Right— One of Moshe Safdie’s drawings of his student thesis project, which already contained many of the ideas that carried through into future Habitats.

Right— Housing cluster study for Habitat 67.

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Right— Sketch, original Habitat ‘67 plan with a human figure for scale.

Left— Perspective sketch of Habitat 67 illustrating the rich life imagined on the copious private terraces.

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Above— One of the many unit floor plans of Habitat 67.

Right— Axonometric drawing of unit and circulation at Habitat 67.

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Left— Blue-sky thinking: a colored sketch of the original Habitat 67 plan.

Right— Circulation study from the schematic design phase.

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Above— Site Plan for the original Habitat 67 proposal.

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Left— Elevation sketch, original Habitat 67 plan.

Right— Presentation sketch, original Habitat 67 plan.

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Right— Moshe Safdie’s proposal for the unbuilt Tropaco Resort: modular structures prefabricated for low-impact harmony with the Virgin Islands landscape.

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Credits— All images courtesy of Moshe Safdie Fonds, John Bland Canadian Architecture Collection, McGill University Libraries.

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MIES VAN DER ROHE

REVIEWS BOOK Mies van der Rohe: An Architect in His Time, Dietrich Neumann, Yale University Press, 2024 Michael Webb

Above right— Plan of 860– 880 Lake Shore Drive, Chicago, which set the template for modern highrise living.

Below— Interior of New National Gallery, Berlin.

Modern Architecture and Urban Studies at Brown, he combines academic rigor with the passion of a sleuth, tracking clues in the archives and identifying lost or forgotten works by the master. In previous books he explored the genesis and reincarnation of the Barcelona Pavilion, and the project to reconstruct the Villa Wolf, Mies’ first modern house, which was destroyed in World War II. Now he has distilled his fieldwork and meticulous research into this comprehensive survey of Mies’ built and unrealized work.

Every significant project is analyzed for its individual qualities and defects, and its place in the evolution of the architect’s career.

The account begins with Mies’ apprenticeship with Peter Behrens and ends with his crowning achievement, the New National Gallery in Berlin, completed a year before his death, just a short walk from where he began his practice a half century before. His early, tradition-bound houses gave little hint of what was to come: visionary sketches of glass and steel skyscrapers, whose sculptural forms are far bolder than the rectilinear towers he would construct in the United States, and free-flowing residential projects. The first two decades of Mies’ career were full of unrealized schemes and buildings (such as his monument to the abortive German communist

MOMA

No architect had a greater impact on the skyline of American cities than Mies. His residential towers on Chicago’s Lake Shore Drive redefined high-rise living and his Seagram Building remains the gold standard of corporate modernism. Unfortunately, as with Le Corbusier’s Ville Radieuse, an idealistic premise was devalued by countless cheap copies. Banal curtain-walled slabs proliferated in every downtown, and poorly maintained high-rise housing estates became vertical slums, provoking a sharp reaction to the modernist aesthetic. So, it’s refreshing to return to the source and re-evaluate Mies’ achievement through the eyes of a discerning architectural historian.

Why read yet another monograph on an architect whose works and cryptic utterances have been repeatedly examined?

Neumann provides the answer with a compellingly readable text that is full of discoveries, fresh insights and balanced assessments.

As Professor of the History of

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PUBLIC DOMAIN

uprising of 1918–19) that no longer stand, his unsuccessful efforts to build for the Third Reich, and his struggle to re-establish himself in the United States.

Neumann recounts this saga with cool detachment, allowing the facts to speak for themselves.

There’s the constant pursuit of perfection at the expense of practical considerations. Exhibit A is the Farnsworth House, a matchless work of art that is hard to live in. Neumann examines the plug-welds that create an invisible joint between I-beam supports and the deck, making it appear to float weightlessly. But he gives equal attention to the failings. The roof leaked, the single-pane glass provided no insulation and produced condensation, and the unscreened porch was infested with mosquitoes. There was no airconditioning, so the owner froze in winter, boiled in summer. Though the house is raised off the ground, it has been repeatedly flooded by the nearby river. Client and architect engaged in mutual lawsuits that could have ruined Mies’ reputation and derailed his American practice soon after its birth.

Instead, Mies became the towering figure of his time, embodying the architect as artist- engineer, creating signature buildings for universities, corporations, museums and enlightened developers. All were variations on the grid, in plan and elevation, distinguished only by subtle shifts in material and detail.

The National Gallery in Berlin was a direct heir of the unrealized Bacardi headquarters in Cuba and the final manifestation of a life-long quest for a universal space that could be in any place for almost any purpose.

It’s not a concept that commands much support today; Neumann leaves it to the reader to decide if the formal beauty of these structures makes up for their shortcomings.

BOOK Don’t Build, Rebuild: The Case for Imaginative Reuse in Architecture, Aaron Betsky, Beacon Press, 2024 Liliane Wong Almost 20 years after curating the 11th Venice Biennale, Aaron Betsky continues to probe the question of an architecture beyond building in his new book. Penned at a time when reuse and its permutations dominate the discussion on the future of architecture, Betsky chronicles the most recent chapter in the reuse narrative and establishes that there is no alternative for the profession. Both a title and an imperative, Don’t Build, Rebuild is a clarion call.

With the premise that the construction energy debt is “impossible to pay” without the use of existing structures, Don’t Build, Rebuild is a significant addition to the literature on reuse.

Eschewing carbon, Betsky enters the discussion of circularity not as material science, but as a critique of Western historic preservation.

A century and a half since the

Above— William Wyld’s 1852 painting Manchester from Kersal Moor contrasts a pastoral foreground with industrial smokestacks.

contentious nineteenth-century debates of Viollet-le-Duc, John Ruskin, and William Morris on restoration versus conservation, Betsky acknowledges the past as a contested place. With preservation posited as power-structure affirming and adaptation as authority-investing, he probes the afterlife of repair and maintenance with a 21st century call for “dumpster diving” and “urban mining.”

These concepts are explored in five parts: “Foundations” provides theoretical and historical context, while “Traditions” and “Uses” offer a contemporary account of reuse reflecting Western society’s transition from production to consumption. In narrative form —at times personal—a special history emerges through a panoply of precedents: unique projects that demonstrate an oftenunconventional implementation of circularity within existing structures, spaces, systems, and objects, and those who occupy them. “[T]o make architecture… you don’t have to make buildings.”

This statement has global Vertical Urbanism 4 II / 2025 INSIGHT 159

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celebrates the past by promoting multiple relations and interpretations; and creates community through reinhabitation. These principles are richly illustrated with reuse projects from the constructed to the ephemeral and the re-wilded— examples that are differentiated from projects that pay lip service to reuse, but rarely accept and celebrate the imperfect.

The intended audience certainly includes the architecture profession, but the reference to the imagination does not necessarily pertain only to design creativity.

Betsky’s principles are, after all, not stylistic. Rather, imaginative reuse conjures a vision of a society in which spatial, functional, and constructional endeavors are unconstrained in finding beauty in the ordinary.

It is an invitation for all to speculate on making a commitment to such a world, without which architecture’s carbon debt could never be repaid.

William Wyld’s 1852 Manchester from Kersal Moor, a painting of billowing urban smokestacks framed in a foreground of unspoiled countryside, depicts the impact of the Industrial Revolution through a nostalgia for the world before. The book offers us the view looking ahead, imagining the society we can be, in which—as Betsky quotes from The Architecture of Persistence: Designing for Future Use— “Keeping a building is an act of optimism.”

BOOK Cooperative Conditions: A Primer on Architecture, Regulation and Finance in Zurich, Anne Kockelkorn, Susanne Schindler, and Rebekka Hirschberg, GTA Verlag, 2024

Below— MASS MoCA showcases industrial buildings transformed into an arts hub through ambitious adaptive reuse.

Casey Mack The cover of Cooperative Conditions says “urgency”: not waiting to be opened, it displays the book’s table of contents like the program of a manifesto, one made from the eight conditions its authors identify and articulate as key ingredients for the making of Zurich’s nonspeculative cooperative housing.

Today, this type makes up 18% of all housing in the city.

While manifestos normally assert what should be rather than what is, this one is built from a mass of often stunning evidence in the form of experiences and practices manifested in housing that people actually live in—not a condition to take for granted in a world where exchange of money for a home is often more im-portant than using it. The result of research conducted with graduate students in the Department of Architecture at ETH Zurich, the book’s findings emerge from the city’s more than a century-old tradition of nonprofit housing, first appearing after World War I in an effort to fight rent gouging.

Studied through 20 cooperatives constructed from that period up until the latest in 2021, the book is not a floor plan manual.

Rather, these precedents are drawn on ad-hoc in analytical texts, diagrams, graphs, photos, and sometimes plans to unpack the manifesto, ranging over the eight critical conditions: An Idea of Sharing, Public Opinion, Nonspeculation, Equity, Debt, Land, Zoning, and The Competition.

Unlike any architecture book of the instrumental “learning from” genre that I’m aware of, this one goes into intense and at times almost excruciating financial

MASS MOCA

relevance, especially in the United States in 2023, where, according to a 2024 AIA report, 52% of construction was new and 45% was renovations, rehabilitations, retrofits, and preservation. Betsky queries architecture’s singleminded preoccupation with conventional design standards and users’ prerequisites for sanitized concepts of space, both of which account for adaptations and renovations that warrant the wholesale removal of the past.

The call to “dumpster-dive” is then a call for a paradigm shift in which “we accept that architecture can look as varied and complex as the rest of our world, can weather and change over time, and will need to be repaired regularly.”

Betsky argues that without this shift, the implementation of a true circular economy within our built environment will be but a hollow effort.

What will such a shift require?

A way forward is offered in “imaginative reuse,” a term of the author’s making. As a blueprint for the future, imaginative reuse counteracts the current state of the built environment, where what we build, preserve, and reuse “reflect[s] the values, beliefs and mandates of those who commission” them in a capitalist economic system. The principles of imaginative reuse are delineated in the introduction; they embrace the social function of architecture as one that breaks through the hierarchies of class, sex, and race; reveals and

REBEKKA HIRSCHBERG

descriptions. These monetary mechanics show how Zurich’s cooperatives are made possible, gleaned through the knowledge of architects, and also the broader ecology of city officials, co-op board members, residents, bankers, and pension fund managers. Rather than providing subsidies, the government assists with laws, access to land, and mortgages. Digesting these financials is well worth it for what we see them enable: beautiful homes built to last, controlled by their residents, with rents based only on construction and maintenance costs. Indeed, renting is a norm for people with various incomes, and a fine option in a nation with a strong social safety net, plus banks and government offering support.

Durability is achieved through innovative ways of using shared and private spaces over time as much as quality materials. These generous and often experimental living environments—for example, co-ops developed just for single women in the 1920s, and 21st century ones evolved from the liberties of squatter renovations in the 1980s—are achieved, not despite their being nonspeculative, but rather because of it. This is the authors’ most emphatic point: freedom from market pressure’s standardization leads to architectural freedom.

The book is also emphatic about the “both-and” reality of Zurich cooperatives: they both rely on speculative capital and are outside of it. They constitute an impure utopia. While renting makes long-term sense in these co-ops, for many it is also necessary due to extremely high prices on the open market, putting ownership out of reach. Yet many cooperatives can borrow against the market-rate value of their land that has appreciated tremendously, creating so-called “hidden reserves” for substantial loans for capital improvements and other major projects. Unlike New York State’s Mitchell-Lama cooperatives, a dissolved co-op’s proceeds can,

Above— Kraftwerk 2, Heizenholz, Zurich: terraces and verandas weave through the building’s levels, creating shared outdoor spaces for living collaboratively.

Anne Kockelkorn, Susanne Schindler and Rebekka Hirschberg

Cooperative Conditions 1 2 3 4 5 6 7 8

An Idea of Sharing Public Opinion Nonspeculation Equity Debt Land Zoning The Competition

A Primer on Architecture, Finance and Regulation in Zurich

gta Verlag

by law, only support the same public value of deeply affordable housing. The original trust vested in the money’s cooperative purpose must be preserved.

To what degree is Zurich’s co-op system buoyed by the nation’s secretive banks offering a global tax haven? Or Swiss culture’s commitments to civic duty, like mandatory military service? These features and others should be kept in mind as the authors express their wish to transfer Zurich’s examples elsewhere.

As Richard Sennett has noted, affluence creates an aversion to sharing. With housing speculation practiced very much as the main path to affluence, the future of sharing is in question.

Cooperative Conditions’ urgency stems from the awareness that this path is unsustainable—at least for the majority of the world.

Most of the world needs better options, both financially and architecturally, and so, as a “primer,” this book’s audience extends beyond architects.

While the ecology of the Zurich cooperative resists out-of-the-box transfer elsewhere, thanks to the wealth of practices the authors describe, its components can be grafted with other cooperative desires and practices. The

condition lending itself to most rapid adoption might be The Competition. Zurich’s mandatory and often open competition system for cooperative developments on city land is one led by architects who are paid for their ideas, not developers fixated on the quickest return on investment. Though Cooperative Conditions’ greatest success is in its thorough entwining of form and finance, we need to first imagine elsewhere what a cooperative future can look like.

And then how it’s paid for.

EXHIBITION Skyscrapers by the Roots: Reflections on Late Modernism, Musée d’art contemporain de Montréal (MAC), Quebec, Canada.

Until 10 August 2025.

Michèle Champagne Summer in Montréal means bike lanes, park hangs, orange cones, and high-performance cranes. Add to that Skyscrapers by the Roots, an exhibition at the Musée d’art contemporain (MAC), and you have one more reason to visit.

Curated by François LeTourneux, the show explores the logics of height, density, and late modern form—but also the social and political conditions that shaped their rise in postwar Vertical Urbanism 4 II / 2025 INSIGHT

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Above— Lynne Cohen, International Square, OACI, Montreal (1977).

Digital print (Exhibition copy), 2024.

Courtesy of, and with the generous support of the Estate of Lynne Cohen and Andrew Lugg.

LYNNE COHEN

Canada and continue to shape Quebec today. The exhibition looks specifically at the decades between World War II and the Révolution tranquille, the democratic reform movement that reshaped Quebec in the 1960s.

To do so, it draws on recent and newly commissioned works by Shannon Bool, David Hartt, Kapwani Kiwanga, Rachel Rose, and Jonathan Schouela, alongside works from the 1960s and 1970s

by Lynne Cohen and François Dallegret. Dual-language wall texts (French and English) are clear and accessible, and the show opens with a compelling collection of books and magazines that frame the discourse.

Artist David Hartt, working across media, engages directly with the legacy of modern architecture—its forms, façades, and the dynamics of center and periphery. His new film Horizon, commissioned for the exhibition, reflects on his sister’s mixed family life. Of Caribbean heritage, both were adopted

by Jewish anglophones and raised in Beaconsfield, a Montréal exurb with sweeping views of the city. Hartt’s childhood sense of alienation parallels the emotional distance often ascribed to modern architecture. And yet, he recalls Montréal’s bold modern forms as a kind of “imaginative refuge.”

His film walks a line between documentary and subjective narrative—an approach rooted in Canada’s robust documentary tradition. At one point, characters break into dance in a suburban backyard, flanked by a replica fragment of the Hôtel Château Champlain’s distinctive prefabricated façade. Designed by D’A stous & Pothier and completed in 1967 for Expo, this 38-story landmark—dubbed “the cheese grater” for its semi-circular windows—was the tallest hotel in Canada when completed.

In May, MAC partnered with the Cinémathèque québécoise to screen four of Hartt’s short films alongside Jacques Tati’s Playtime (1967). The French director’s

slapstick classic critiques modern Paris with dry humor and visual gags, following Monsieur Hulot as he bumbles through glass-walled offices, prefab apartments, and overly rational restaurants. The film’s absurdism—underscored

by François Lemarque’s lively score—was a direct influence on photographer Lynne Cohen, who appears in Skyscrapers. Seven black and white images are on view, several of them taken at Montréal’s Place Bonaventure between 1975 and 1979.

Completed in 1967, Place Bonaventure was then the world’s largest concrete building, and remains a brutalist icon: hotel, offices, exhibition spaces, and rooftop garden all integrated atop a subway station. Cohen’s lens found uncanny beauty in the strange hybrid spaces of the era— travel expos, awkward furniture displays, and lonely plants. Her 1977 photograph International Square, OACI, Montréal, depicts a pristine architectural model of the ICAO headquarters, a UN agency based in Montréal. Cohen’s “found interiors” recall the formal rigor of Walker Evans and Lewis Baltz but are laced with absurdity, reminding viewers how people inhabit—and sometimes subvert —modernism’s rigid ideals.

Her influence on Hartt is no coincidence. As LeTourneux notes, she was his mentor at the University of Ottawa. Her legacy

threads through the exhibition, offering an intergenerational perspective on how modern environments are occupied, interpreted, and reimagined.

Skyscrapers is housed in Place Ville Marie, a landmark complex by I.M. Pei & Associates and urbanist Vincent Ponte.

Its 47-story cruciform tower, underground shopping concourse, and public plaza were built between 1958 and 1962, and today serve as MAC’s temporary home while its main location undergoes renovation by Saucier + Perrotte and GLCRM. Fittingly, Place Ville Marie was also MAC’s first home in 1965, where it opened with an exhibition of French painter Georges Rouault. This return to the site, LeTourneux explains, was the conceptual catalyst for the show.

That history isn’t just context— it’s part of the exhibition. Archival photos, critical essays, and installation texts turn Place Ville Marie into both host and subject. The skyscraper is not just a vessel, but a living artifact of the late modern period and a symbol of Montréal’s midcentury social, political, and economic transformation. Skyscrapers embraces this specificity. If curators today seek to embed exhibitions in context, this show is a strong case study. It captures the boldness and optimism of the period—without neglecting its contradictions.

that the failures and turbulence of the last 50 years were, in some way, a necessary prelude to the current inflection point. They ask: how does meaningful change happen? The book’s structure assembles a dense weave of ideas and movements into a kind of three-dimensional riddle, with time itself as the critical axis.

Running throughout is a questioning of technology— whether as a tool for adaptation or a symbol of human hubris.

Though this is not a book about buildings in the traditional sense, it is about the cultures that construct them. There are some radical case studies—such as Colin Moorcraft’s 1972 Designing for Survival exhibition at the RIBA —but the focus is less on form and more on frameworks. Moorcraft’s declaration that “Architects are part of the problem and must be part of the cure” remains a potent call to action. The book acknowledges inspiring visions of alternative practice, even if these have rarely found traction in the market. It documents the heroes, but not the villains.

The academic tone of the project is both a strength and a

BOOK It’s About Time: The Architecture of Climate Change, Derk Loorbach, Véronique Patteeuw, Saskia van Stein, Léa-Catherine Szacka, Peter Veenstra, with Internationale Architectuur Biënnale Rotterdam, NAI Publishers, 2024

ERNEST TROVA

James Soane It turns out it is always about time to write a book on the climate emergency. No matter how many words have been generated on the subject, few seem to stick. It’s About Time is a necessary reminder of the urgency we face—and one that everyone should read. The message is clear: for those who care about changing the political narratives and ideologies surrounding earth systems, action is imperative.

The planet is out of balance.

The only way forward is to co-create a nature-positive future. As the editors note, “Today we are witnessing the destabilization of the fossil, extractive economic regime.”

Much of the book functions as a primer, charting significant postwar moments—key publications, protests, scientific warnings—through silvered ink timelines and archival materials that illustrate how long the alarm has been ringing. The 1960s and 1970s saw many of today’s environmental challenges already identified. The shock comes in learning how capitalist self-interest has since erased the science, silenced the debate, and quite literally fueled the fires of conspicuous consumption.

Entire ecosystems of thought have been dismantled. And alarmingly, the pace of this erasure has accelerated in the year since the book’s 2024 publication.

At its core, It’s About Time proposes that small-scale experiments, radical local resistance, and political misfires have collectively seeded change “in small incremental steps.” The editors remain cautiously hopeful:

limitation. The compilation leans heavily on thinkers like Foucault, Derrida, and Latour, creating a rich but sometimes insular discourse. At times, the liberal use of “we”—as in “we need to understand how we got here” —assumes a collective agency that is neither global nor evenly distributed. The text rightly critiques this assumption, pointing to the asymmetric power structures that define the climate crisis. The global economy, the book argues, remains an engine of wealth for the few and a machine of extraction and precarity for the many—particularly in the Global South. Disappointingly, there is little sustained reflection on this global imbalance. Given that droughts, floods, and political instability disproportionately affect low-income regions, the omission is notable.

A more grounded critique emerges in the book’s treatment of the architectural profession itself.

The claim that “most architects are not just producers of built form; they make studies, do research, present ideas, talk to politicians, teach, write” feels well-intentioned but out of touch. In the United

Right— Ernest Trova’s 1971 silkscreen Save Our Planet fuses his iconic Falling Man motif with a prescient call for environmental awareness.

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In doing so, it reduces the frequency and intensity of combined sewer overflows, one of the city’s most persistent ecological hazards. Drake uses the park as a springboard for a broader narrative on the entanglement of water, waste, policy, and design in the urban environment.

Physically, the project consists of a series of planted street-ends, bioswales, and bioretention areas built along the canal. These landscaped zones are designed to intercept and treat runoff from surrounding streets, while also offering new pockets of public space at the water’s edge. The first pilot installation, completed at Second Street, serves as proof of concept, modest in scale but rich in implication for how post-industrial urban edges might be reimagined.

Structured in five thematic sections (Investigation, Problems and Conflicts, Planning, Design, and Future Projections), the book traces the layered challenges of realizing even a modest section of green infrastructure in a dense, bureaucratically complex environment. The reader is reminded that Gowanus was once a tidal creek in a salt marsh valley, transformed into a canal over the course of the 19th century by industrial ambition and environmental neglect.

Mapping its geological, industrial, and social past, Drake makes space for imagining its reinvention.

Rather than presenting a polished object, Sponge Park is

BOOK Sponge Park: Nature-Based Infrastructure for Cleaner Urban Environments, Susannah C. Drake, Park Books, 2024 Bram Monson How do you reimagine a site so steeped in toxicity that it’s become synonymous with urban decay?

In Sponge Park: Gowanus Canal, Susannah Drake, founder of DLANDstudio, offers not only an answer, but a compelling case study in regenerative urbanism.

The book documents the effort to conceive, advocate for, design, and build a modest yet revolutionary piece of green infrastructure along Brooklyn’s Gowanus Canal, one of the most polluted waterways in the country and a designated Superfund site since 2010.

The “Sponge Park” is not, as the name might suggest, made of sponges. Rather, it’s a performative landscape that absorbs and filters stormwater runoff before it enters the city’s combined sewer system.

164 Vertical Urbanism 4 II / 2025 INSIGHT

Right— The Sponge Park, Gowanus Canal, Brooklyn, filters stormwater, restores ecological function, and reclaims public space along a polluted industrial edge.

a process-driven story, one that blends memoir, field report, and a call to action. Drake’s tone is personal but precise. She positions the Gowanus project within a longer arc of ecological design, while grounding her narrative in the particularities of Brooklyn’s shifting waterfront.

What emerges is a belief that infrastructure can, and should, do more. It can perform technically while engaging socially. It can slow water, restore ecological function, and create space for public life.

The project’s value lies not in its scale, but in its ability to show how small, well-designed interventions can reshape the relationship between city and water.

In a moment when much of the waterfront is being developed for private interest, Sponge Park offers a more civic-minded approach, one that foregrounds long-term stewardship, and encourages public investment.

The book is handsomely designed, with diagrams, archival maps, and photographs that complement the text.

For readers interested in green infrastructure, urban ecology, or the politics of urban design, Sponge Park is both a practical guide and design manifesto.

It insists that we pay attention to water not just as a risk, but as a resource. As cities confront increasingly unpredictable climates, the lessons of Gowanus may well flow far beyond its canal walls.

SUSANNAH DRAKE

Kingdom, for instance, architects design only an estimated 6% of buildings. If real transformation is to occur, it must be demanded of the global construction industry, not just its intellectual fringe.

Ultimately, It’s About Time is a timely and comprehensive account of how the West has tried—and failed—to address anthropogenic climate change. The problem is not a lack of imagination, empathy, or strategy. It is a lack of consensus, and above all, of political will. Market forces have accelerated the crisis, but the book urges readers to flip the script: become the accelerator, the activist, and the ancestor. That means slowing down, mobilizing communities, and applying technological innovation wisely.

The editors end on a note of hope.

That one might close the book feeling the opposite—resigned, overwhelmed—is not a failure of the argument, but a measure of the scale of the challenge.

How much time is left?

LIAM YOUNG

BOOK Architecture and Videogames: Intersecting Worlds, Vincent Hui, Ryan Scavnicky, and Tatiana Estrina, Routledge, 2025.

James Delaney If you’ve ever been curious about the architecture and spaces of video games, Architecture and Videogames is an essential starting point. Beyond mapping the many ways in which the two disciplines overlap, the book raises compelling questions about architectural theory, pedagogy, and practice in relation to the rapidly evolving medium of video games. What does architecture have to do with video games? Everything. And the influence is reciprocal: architects may be surprised to discover just how deeply video games are shaping architectural methods, aesthetics, and culture.

This edited collection of essays, interviews, and case studies presents a comprehensive view of what might be called video game urbanism. It is organized into seven thematic sections, each examining a distinct facet of the relationship between architecture and video games.

The opening section, “Cultural Artefacts,” begins with the argument that video games are cultural artefacts on par with buildings. In “Baby What’s ROM?,” Galo Canizares shows how gaming culture offers critical tools—particularly media archaeology and “retrogaming”— for understanding architecture produced in the digital era, much of which remains locked in obsolete file formats.

Thoreau Bakker and Kristopher Alexander’s essay, “The Interplay of Architecture and Gameplay in Dark Fantasy,” draws striking parallels between the design logics of the Dark Souls series and urban imaginaries found in Los Angeles or Grand Theft Auto. Their contribution argues for greater collaboration between these two inherently spatial disciplines.

The second section, “Historic Reproduction,” explores how virtual tools enable reconstructions of the past. Kristian Howald, Michael Carter, and Namir Ahmed document their virtual reconstruction of a 16th century Iroquoian longhouse, demonstrating the value of videogame hardware and software for archaeological storytelling and heritage preservation. An interview with Maxime Durand, historian at Ubisoft, reveals the tension between historical authenticity and gameplay demands, with examples drawn from the Assassin’s Creed franchise.

“Production Technologies” takes a more technical turn.

Zak Fish describes the increasing influence of videogame tools— such as photogrammetry and point cloud modeling—on architectural workflows, noting that we are approaching a “fullcircle moment” in which the digital tools once inspired by real architecture are now reshaping it.

An interview with Conor Black and James Ward from Arup supports this claim, while also sounding a note of caution about relying too heavily on entertainment-driven design platforms.

In “Design Pedagogies,” Damjan Jovanovic’s essay “Infinite Play” outlines how videogames might transform design education

Above— Still from Liam Young’s Planet City: a speculative vision imagining a single hyperdense metropolis as a response to climate crisis and planetary sprawl.

by disrupting traditional workflows and unlocking new forms of creative exploration.

The fifth section, “Proxies and Representation,” includes Sandra Youkhana and Luke Caspar Pearson’s “Game Worlds as Real Worlds,” a standout essay that offers cartographic analyses of iconic videogame environments.

Their work exemplifies how architectural drawing techniques can shed new light on game design—and how game design, in turn, can inform architectural representation.

“Bridging Worlds” examines how virtual spaces can inspire physical ones, with a focus on inclusivity, interaction, and creative play in real-world design.

The final section, “Projected Futures,” speculates on what lies ahead. Topics range from AI and procedural generation to philosophical questions about authorship and the evolving role of the architect in digital space.

Overall, Architecture and Videogames is a vital resource for architects, designers, and researchers interested in digital environments, spatial storytelling, and emerging technologies. Its eclectic mix of theory, pedagogy, and practice makes a persuasive case for greater engagement between the fields of architecture and videogames. In a world where the line between real and virtual space is increasingly blurred, this book is both timely and necessary.

Vertical Urbanism 4 II / 2025 INSIGHT 165

Best Tall Building

by Height Under 100 Meters z Eden, Frankfurt am Main, Germany z One River North, Denver, US z Populus, Denver, US z Sirius, Sydney, Australia z Sun Tower, Yantai, China z T3 Bayside, Toronto, Canada

CTBUH wishes to congratulate the Award of Excellence Winners in the 2025 program.

Each of these projects will compete for the Overall Best award in their respective categories at the 2025 International Conference in Toronto, between 6–9 October.

100–199 Meters z EDGE East Side Berlin, Berlin, Germany z Graduate Tower at Site 4, Cambridge, US z Habitat Qinhuangdao, Qinhuangdao, China z Shanghai Poly Pukai Financial Center, Shanghai, China z The Henderson, Hong Kong, China z ZIN in No(o)rd, Brussels, Belgium 200–299 Meters z CITIC International Building, Shenzhen, China z Karlatornet, Göteborg, Sweden z Queen’s Wharf, Brisbane, Australia z The Axiom, Shanghai, China

For more information please visit awards. ctbuh.org/winners/ or click on the QR code below.

166 Vertical Urbanism 4 II / 2025

300 Meters and above z Ciel Tower, Dubai, UAE z CITYMARK CENTRE, Shenzhen, China z Merdeka 118, Kuala Lumpur, Malaysia z Ping An Financial Center, Jinan, China z Zhangjiang Science Gate Twin Towers, Shanghai, China

Best Tall Building

by Region Americas z 1900 Lawrence, Denver, US z Alberni by Kengo Kuma, Vancouver, Canada z Five Park, Miami Beach, US z Graduate Tower at Site 4, Cambridge, US z One Madison Avenue, New York City, US z One River North, Denver, US z Ontario Court of Justice Toronto, Canada z Populus, Denver, US z T3 Bayside, Toronto, Canada z TD Terrace, Toronto, Canada z The Eight, Bellevue, US z Winthrop Center, Boston, US Asia z CITYMARK CENTRE, Shenzhen, China z Habitat Qinhuangdao, Qinhuangdao, China z Merdeka 118, Kuala Lumpur, Malaysia z Shanghai Poly Pukai Financial Center, Shanghai, China z Shenzhen Transsion Holdings Headquarters, Shenzhen, China z The Henderson, Hong Kong, China Europe z EDGE East Side Berlin, Berlin, Germany z Karlatornet, Göteborg, Sweden z ZIN in No(o)rd, Brussels, Belgium

Middle East & Africa z Azrieli Center Modi’in, Modi’inMaccabim-Re’ut, Israel z Ciel Tower, Dubai, UAE z Landmark TLV Tower A, Tel Aviv, Israel Oceania z 1 Elizabeth, Sydney, Australia z 39 Martin Place, Sydney, Australia z Indi Sydney, Sydney, Australia z Queen’s Wharf, Brisbane, Australia z Sirius, Sydney, Australia

z Future Project z 63 St Mary Axe, London, UK z Dubai Edition Hotel: Vertical Oasis, Dubai, UAE z False Creek Mass Timber Community, Vancouver, Canada z Forbes International Tower, Cairo, Egypt z Lawrence East - TOC (TransitOriented Community), Toronto, Canada z Philadelphia TOD, Philadelphia, US z Regenerative Tree, Tokyo, Japan z Tencent Helix, Shenzhen, China z Vertical Landscapes, Tokyo, Japan

Urban Habitat z CIBC Square I, Toronto, Canada z Dongguan Central Park, Dongguan, China z Galataport Istanbul, Istanbul, Türkiye z Tamachi Tower, Tokyo, Japan The Well, Toronto, Canada

10 Year z Al Marya Tower, Abu Dhabi, UAE z BBVA México Tower, Mexico City, Mexico z Grogan | Dove Federal Office Building, Miramar, US z Shanghai Tower, Shanghai, China z Sky Habitat, Singapore

Repositioning z JingIN International Center, Beijing, China z PENN 2, New York City, US z Tribune Tower, Chicago, US z ZIN in No(o)rd, Brussels, Belgium

Vertical Urbanism 4 II / 2025 167

Construction

Structure

Space Within

z 8 Phillip Street, Parramatta, Australia z CCFED Science and Innovation Building, Guangzhou, China z Central Bank of Iraq, Baghdad, Iraq z Construction Logistics at Varso Tower, Warsaw, Poland z Istanbul Finance Center, Istanbul, Türkiye z One Bloor West, Toronto, Canada z Southbank Place, London, UK z Wasl Tower, Dubai, UAE

z One Bloor West, Toronto, Canada z One Pearl Bank, Singapore z Sydney Metro Martin Place Integrated Station Development (SMMPISD), Sydney, Australia z Tree of Life, Xi’an, China z Two Manhattan West, New York City, US

z Booking.com City Campus, Amsterdam, Netherlands z COFCO Qianhai Innovation Center, Shenzhen, China z Landmark TLV Tower A, Tel Aviv, Israel z Scotiabank North Flagship, Toronto, Canada z The Henderson, Hong Kong, China

Façade

Equity, Diversity & Inclusion

Innovation z (Re)Euston – Towards Concrete Reuse at Scale, London, UK z Cast Steel Solution for CIBC Tower II, Toronto, Canada z In-situ monitoring of hybrid pile/ raft foundation system, London, UK z Innovative Lateral Stability Solution for Repurposing a PartlyBuilt Supertall Tower into a Modern Sustainable Asset, Dubai, UAE z Leafy: Artificial Gardens of Kinetic Leaves that Help Shape Actual Parks z LIFTbuild z MMC in High Rise Residential Buildings (Mace’s HRS System), London, UK z Silva: Next-Generation Mass Timber Urbanism, Vancouver, Canada z Solar Chimney in Super High-Rise Building, Robotics in Construction, Guangzhou, China

168 Vertical Urbanism 4 II / 2025 INSIGHT

z China Merchants Bank Global Headquarters, Shenzhen, China z Guohua Financial Center, Shanghai, China z TD Terrace, Toronto, Canada z The Henderson, Hong Kong, China z Wasl Tower, Dubai, UAE

Systems z 40 Leadenhall, London, UK z CCFED Science and Innovation Building, Guangzhou, China z Kurita Innovation Hub, Tokyo, Japan z Metro Martin Place Disappearing Access Machines and Transformer Crane, Sydney, Australia z Punggol Digital District, Singapore

z 495 Eleventh Avenue, New York City, US z Employee Resource Groups Support Belonging

64 University Place Proudly Supports

and

Congratulates

and

All 2025’s Award Winners 1440 Broadway New York, NY 10018 T 212 302 9060 F 212 302 9280 www.cnygroup.com 6/6/2025 10:16:16 AM CNY's Half Page Ad CTBUH 2025 Award of Excellence for KPF 64 University 06.06.25 F.indd 1

6/6/2025 10:16:16 AM

congratulates

2025 Award of Excellence Winner:

ONE BLOOR

WEST

CTBUH 2025 Award of Excellence Construction | Structure This recognition is a testament to the power of teamwork, innovation, and shared vision.

Congratulations to all involved.

Motioneering is proud to have engineered a 350-tonne tuned mass damper for this landmark skyscraper.

motioneering.ca

Sirius Building Retrofit by

Architecture

In partnership with Richard Crookes Constructions and SCP Consulting, BVN Architecture has led the transformation of the Sirius Building— an ambitious heritage readaptation that honours its architectural legacy while introducing contemporary living through thoughtful design and advanced engineering.

Vertical Urbanism 4 II / 2025 169

LETTER FROM

SIEBE SWART

Amsterdam, Netherlands Paco Bunnik

What does the future of Amsterdam look like? The city—famed for its canals and progressive spirit—is addressing contemporary urban challenges through the bold Amsterdam Local Vision 2050.

This strategic framework imagines a sustainable, inclusive, and human-scale metropolis that unites heritage with innovation across environmental, economic, cultural and social dimensions.

Amsterdam’s identity is inseparable from water. The city’s historic canal system reflects centuries of ingenuity in managing a landscape that lies largely below sea level. Today, nearly one-third of Amsterdam consists of water— canals, rivers, lakes, and harbors that shape its physical and cultural fabric. Modern flood infrastructure remains vital, but climate adaptation now includes green roofs, permeable surfaces, and urban wetlands that absorb rainfall and mitigate heat. From houseboats to floating neighborhoods, designing with water is second nature here.

To manage growth while preserving its intimate scale, Amsterdam is evolving into a polycentric city. Instead of expanding outward, it is investing in neighborhoods like Nieuw-West, Zuidoost, and Noord—transforming them into self-sufficient hubs with jobs, amenities, and green space.

This relieves pressure on the historic 170 Vertical Urbanism 4 II / 2025 INSIGHT

center and brings daily needs within walking or cycling distance.

Major developments like Zuidas and Haven-Stad embody this shift. Zuidas is transforming from a business district into a multifunctional urban node, while Haven-Stad—redeveloping former industrial land—could eventually house 150,000 new residents. Both prioritize public transit, energy efficiency, and access to parks and water, setting new standards for livable density.

Beyond the city itself, Amsterdam collaborates regionally through the Metropoolregio Amsterdam, a coalition of 32 municipalities and two provinces.

With 2.5 million residents, the region coordinates policy on housing, mobility, economy, and climate—recognizing that Amsterdam’s future is regional, not just local.

Sustainability is at the core.

The city aims to be fully circular by 2050, reducing waste through reuse and innovation in construction. It supports clean energy via solar power, district heating, and fossil-free transport.

Public health is promoted through car-free zones, green schoolyards, and air-quality initiatives.

A key principle—de Amsterdamse aanpak—focuses on investing unequally to create equal opportunity. Resources are directed

Above— Zuidas, the city’s evolving southern district, exemplifies the city’s polycentric growth strategy.

Settled: Circa 12th century Area: 244 km² 188km² land, 56km² water (municipality) Population: 935,000 (city, 2025 estimate) 2,500,000 (metropolitan region) Urban density: 4,973/km² (municipality)

toward neighborhoods facing the greatest challenges, with targeted investments in education, housing, and public space to close systemic gaps.

Amsterdam’s green structure policy strengthens this agenda.

Traffic routes are being reimagined as tree-lined boulevards, and a growing network of green corridors protects biodiversity and provides vital recreational space. These interventions boost climate resilience and support everyday well-being.

Underlying all of this is a commitment to “making the city together.” Residents are seen not as passive users, but as co-creators.

Participatory planning and support for grassroots initiatives reinforce a culture of civic agency—true to Amsterdam’s traditions of freedom, emancipation, and tolerance.

It’s easy to take pride in the city one inhabits. The harder task is preserving its unique character as it grows. That’s why cities must learn from one another—sharing strategies for sustainable, inclusive development that respects the past while embracing the future.

Amsterdam’s model offers a challenge: will our cities continue to sprawl, consuming land and resources? Or can they grow more wisely—through density, ecological preservation, and vibrant, close-knit urban life? Why not?

CTBUH is extremely grateful for the generous support of its membership

PLATINUM

GOLD +

FULL MEMBERSHIP

ӼAECOM ӼAGC Glass Europe ӼArup ӼBuro Happold ӼChina State Construction Engineering Corporation ӼDeSimone Consulting Engineering ӼDow ӼEgis ӼIllinois Institute of Technology ӼIUAV University of Venice ӼJeddah Economic Company ӼKohn Pedersen Fox Associates ӼKONE Corporation ӼLangan ӼMoshe Zur Architects and Town Planners ӼMultiplex Construction Europe Ltd ӼNEOM ӼOtis Elevator Company ӼPERI ӼRFR Asia Limited ӼRWDI ӼSchindler ӼShanghai SIIC North Bund New Landmark Construction and Development Co., Ltd ӼShanghai Tower Construction & Development ӼShenzhen Parkland Real Estate Development Co., Ltd ӼSiderise ӼSkidmore, Owings & Merrill ӼSun Hung Kai Properties Limited ӼTaipei Financial Center Corporation ӼThornton Tomasetti, Inc. ӼTK Elevator GmbH ӼTongji University ӼTurner Construction Company ӼWSP

—Dar —Gensler —KLCC (Holdings) Sdn Bhd —Tishman Speyer

There are an additional 480 members of the Council at the Silver and Non-Profit/Governmental levels. Please see online for the full member list: members.CTBUH.org.

GOLD ӼAdamson Associates ӼAdrian Smith + Gordon Gill Architecture ӼAedas ӼAqualand ӼArcadis ӼBeca ӼBrandston Partnership, Inc. Ӽchapmanbdsp ӼCharles Russell Speechlys ӼCityGroup Design Collective CO., LTD ӼCorgan ӼDCI Engineers ӼDrees und Sommer SE ӼEast China Architectural Design & Research Institute (ECADI) ӼEmaar Properties, PJSC ӼFrasers Property ӼFujitec ӼFXCollaborative Architects Ӽgad ӼGCL Builds ӼGiarratana, LLC ӼGoettsch Partners ӼGVA Lighting, Inc. ӼHongkong Land ӼIMEG Corp ӼMagnusson Klemencic Associates ӼMcNamara ? Salvia ӼMotioneering, Inc. ӼMott MacDonald ӼNucor Corporation ӼPDW Architects ӼPerkins & Will ӼPermasteelisa Group ӼPNB Merdeka Ventures Sdn. Berhad (PMVSB) ӼPNCA - PNC Architects ӼPopulous ӼQingdao Conson Hai Tian Center of China ӼRamboll ӼRise Global LLC ӼSeverud Associates Consulting Engineers, PC ӼSuffolk ӼUrban Villages ӼWindtech Consultants ӼZaha Hadid Architects