In July 2022, Architects Declare approached the Council on Tall Buildings and Urban Habitat to stimulate useful debate on the CTBUH's mission and giving them an opportunity to comment on our call for a shift in their mission. Writing to CEO Javier Quintana de Uña, we said "We are committed to working with organisations that accept the reality of the emergency but have not yet publicly proclaimed this and may not yet have a firm view of how to move forward in any detail. In some cases, we challenge organisations to reconcile the nature of the emergency with their historic remits, purposes and activities. We hope that our draft article will be received in the constructive spirit intended and we look forward to your reply." We never received any response to the original email or our followups. Below is the full text we sent.
'Skyscrapers have had a grip on our collective imagination ever since the 19th century. Elisha Otis demonstrated the first safe elevator in 1853 at the New York World Fair by standing on it and having an axeman cut through the only rope supporting it. Little could he have known that his invention, together with advances in metallurgy, would have ushered in a heroic age of increasingly tall buildings. With the Empire State Building, the Chrysler Building and many others celebrated in popular culture, tall buildings have become icons of architectural and engineering prowess. The Council on Tall Buildings and Urban Habitats has done much to celebrate this and, since the 1980s, has maintained the definitive ranking of the tallest buildings in the world.
'Times however have changed, and skyscrapers are no longer what they were. We are now in a planetary emergency and we have very few years left in which to chart a new and safe course for humanity. The evidence now is overwhelming that tall buildings hinder, rather than assist, our efforts to address key challenges of climate breakdown, resource depletion and biodiversity loss.
'Today, UK Architects Declare is therefore calling on CTBUH to transform its register of ‘The World’s Tallest Buildings’ and shift its focus from a fixation on height to the other part of its mission, Urban Habitats, and crucially address critical environmental challenges. This is not exactly a case of saying “The party’s over” - it’s more that the party is now elsewhere and CTBUH is well placed to be actively involved. The register is promoting system behaviour that is totally at odds with addressing the planetary emergency. Arguments put forward for the sustainability of certain practices has often been based on ‘how to make them less bad’ but in a planetary emergency ‘less bad’ is nowhere near good enough. We need to work towards a regenerative paradigm in which everything we do as humans has a net positive impact and we integrate all our activities into the web of life that supports us.
'Is our challenge justified and where is the evidence to back up our assertions? A 2017 study commissioned by CTBUH would appear to challenge these assertions. It demonstrates that ‘downtown high rise’ developments are better across a range of environmental and quality of life indicators than ‘suburban low-rise’. This reinforces an argument frequently put forward for the sustainability of tall buildings which is that they can deliver the density and compactness of layout necessary to optimise sustainable forms of transport like walking, cycling and mass transit. But this is missing some crucial elements of a complex picture and increasingly we need to ask ourselves “What is the right density and urban form to best address contemporary challenges?”
'A research project carried out by a team at University College London (UCL) has shown that office buildings with 20 storeys or higher typically use two and a half times more electricity than buildings with 6 storeys or fewer. The same study also found a linear relationship between increases in height and greenhouse gas emissions in residential buildings. A recent Dutch study (referenced in the UCL report) has shown empirically that high-rise slabs and towers deliver, respectively, half and a third of the density of low-to-medium rise courtyard forms of urban block (similar to much of central Paris and Barcelona).
'The key element missing from the CTBUH study is exactly this compact approach to cities that delivers a whole range of benefits. A further study has shown that Life Cycle GHG Emissions per capita (LCGE) for high-density low rise is less than half that for high-density high rise. The evidence against tall buildings has continued to pile up, with engineer Tim Snelson from the international consultancy firm Arup calculating that a typical skyscraper will have at least double the carbon footprint of a ten-storey building with the same floor area.
'The unavoidable fact is that, in terms of resource efficiency, the embodied carbon in their construction and energy consumption in use, skyscrapers are an absurdity. The amount of steel required to resist high windspeeds, the energy required to pump water hundreds of metres above ground and the amount of floorspace taken up by lifts and services make them one of the most inefficient building types in a modern metropolis. It could also be argued that skyscrapers further detach us from any meaningful relationship with the natural world. Above about ten storeys, balconies don’t work because it is simply too windy, so high-rise apartments are hermetically sealed – as isolated from nature as possible.
'The challenge now is how do we create the best possible quality of urban life within planetary limits? What is the right relationship between building height and compactness? For instance, it is widely known that compact cities like Barcelona and Paris have much lower transport-related energy consumption than more diffuse cities like Atlanta or Houston. At the other end of the scale, very dense conurbations like Hong Kong or Ho Chi Minh City rarely provide enough open space or parks. We need to establish what architect and writer Lloyd Alter refers to as ‘the goldilocks density’ – compact enough to allow transformative approaches like the 15-minute city but not so dense as to reduce green space:
'"At the Goldilocks density, streets are a joy to walk; sun can penetrate to street level and the ground floors are often filled with cafes that spill out onto the street, where one can sit without being blown away, as often happens around towers. Yet the buildings can accommodate a lot of people: traditional Parisian districts house up to 26,000 people per sq km; Barcelona's Eixample district clocks in at an extraordinary 36,000."
'There is still lots to be debated in this field and your organisation could lead on this in recognising and promoting urban buildings that accelerate the essential shift from ‘sustainable’ to ‘regenerative’ design and development.
'This article started with a brief history of how skyscrapers came to be symbols of progress. To growing numbers of people they now represent extravagant status symbols and profligate ways for cities to compete and the super-rich to invest in property. Some will protest these assertions, and it would be correct to say that the CTBUH has promoted a lot of useful research in the area of sustainability and tall buildings. But this is based on an increasingly discredited definition of sustainability – mitigating the negative impacts of something without thinking about whether, as a society, we should be doing it in the first place.
'As Sarah Ichioka and Michael Pawlyn have described in a new book Flourish: Design Paradigms for Our Planetary Emergency, the way we frame subjects and the stories we tell about our societies and economies are going to be critical to whether we can chart a safe course for the future of humanity: "... increasing numbers of us are asking the question "Progress towards what?" For those that might still claim that skyscrapers are symbols of progress, the evidence is clear they now represent progress towards societal collapse.'
20 November 2022