50 Forward: Innovations and Urban Interventions

The CTBUH network was asked: What are the innovations—the technologies, processes, digital tools, and advancements—that will change the way we occupy and build cities 50 years into the future? Which urban interventions—either in conceptual or planned stages—will contribute to the wider urban habitat and influence the way we build cities 50 years from now? CTBUH issued an open call for nominations in both of these categories. Submissions have been edited for content and clarity.1

Biomimicry / Biological Design

Biological Urban Lighting

Light pollution will only increase as cities grow and densify, but it can have deleterious effects on surrounding wildlife, disrupting migratory patterns and creating ripple effects through ecosystems that have not yet been fully understood. Pervasive, 24-hour-a-day lighting can have negative effects on the health of humans too, such as reduced sleep quality. Another environmental issue of continuous lighting has been its electricity-dependence, and resultant carbon dioxide emissions. The current solution for this has been to transition most high-pressure sodium (HPS) streetlights to light-emitting diodes (LEDs), which are more energy-efficient, but emit a brilliant (and disruptive) bluish-white light. Researchers are currently looking into the application of bioluminescence to tackle light pollution with both these objectives: creating a more wildlife- (and human-) compatible source of continuous public lighting and increasing the energy efficiency of citywide lighting in general. Bioluminescent lighting, while still in the research phase, has the potential to harness the glow of bioluminescent algae and fungi for use in daily civic life. The natural phenomenon of bioluminescence is a solar-powered, enzymatic reaction and is activated by agitating the organisms. Researchers are currently examining how to increase the lifespan of the reaction, potentially by splicing bioluminescent genes with existing natural features, such as trees.

Ubiquitous, Vegetated Buildings
As noted in “50 BACK: Urban Interventions That Changed the World’s Cities,” there is increasing momentum toward using vegetation as part of the façade strategy of tall buildings, as well as an enhancement of interior and semi-enclosed spaces. This is about far more than aesthetics. If cities are to make more than a superficial impact on reducing the urban heat island effect, we will need to make sure that more of the new built surfaces we create are not hard, “mineralized” reflective materials, as they are today. While progress to date is laudable, in the near future cities will become noticeably greener—and quieter—as the environmental, mental and physical health benefits of vegetated skyscrapers become more evident, and more convincingly incorporated into pro formas and other calculations of return on investment.

Construction & Materials

Additive Construction with In-Situ Resources Utilization (ISRU)

Additive construction with in-situ resources utilization (ISRU), is an outcome of technology developed for NASA to facilitate construction of structures on the Moon and Mars. Over a half year, the technique has progressed from concept design to prototyping. The project culminated in a 4.5-meter-tall exterior shell, 3D-printed by in under 30 hours, complete with robotically installed windows and doors. The underlying premise of the technology is to additively construct (3D-print) with raw materials harvested from the planetary surface. This is significant, because “importing” Earth materials to Mars would be prohibitively expensive; as such, the technology uses a thermoplastic composite made of two Mars-relevant materials, polylactic acid (PLA), and basalt. The material, in pellet form, is fed through a heated extruder attached to a robotic end-effector. The printed material, tested and subsequently validated by NASA, is 1.5 times stronger than concrete in compression and 30 times stronger in tension, with superior durability and freeze-thaw performance. Importantly, the material is also found in abundance on Earth. As a proof-of-concept, the Mars habitat prototype will be deconstructed, its material recycled, and reprinted as a fully operational and permanently occupied Earth habitat by late 2019.

Additive construction with in-situ resources utilization (ISRU), is an outcome of technology developed for NASA to facilitate construction of structures on the Moon and Mars. © AI. SpaceFactory

Today, nearly all 3D-printed buildings are printed off-site in factories, transported and assembled as concrete sections. This process addresses neither the material resources nor supply chain issues that impact the embodied energy of buildings. Concrete and steel, the building blocks of cities, are hugely energy-intensive to manufacture, transport, and assemble—contributing to nearly 10 percent of global carbon emissions.

Fifty years forward, buildings will be autonomously 3D printed from renewable and recyclable resources gathered from around a site and layered into any shape, size, and height. Biopolymer-fiber composites are vastly more energy- and material-efficient than concrete, are equivalent in performance, and are recyclable and biodegradable. Advancement of 3D printed, ISRU technology will move us from a linear mindset of "take, make, waste" to the circular recovery and renewal of buildings—harvested from, and returned to the earth.

Drone-Based Automated Façade Inspections

Drone-based façade inspections are already a reality, and are expected to become more prevalent in the near future. © Helios Vision

Using drones for construction and building inspections will increase safety, efficiency, and decrease the cost required to maintain tall building façades. Drone-based construction monitoring and façade inspection services utilize industry-leading automated flight planning software to vertically scan high-rise buildings faster and safer than via traditional methods. The images and video collected can be used during quality assurance (QA) closeout, or during ongoing inspections and maintenance sessions, to identify areas of interest.

Mass Timber

Seemingly, not a day goes by without a new, spectacular mass-timber building project being announced. The world’s tallest all-timber building, Mjøstårnet in Brumunddal, Norway, was completed in early 2019 at 85 meters. There are proposals for structures as high as 350 meters on the boards, but more importantly, hundreds of “average” multistory buildings that would, in the past, have been conventionally constructed with concrete and steel, are now being planned with mass timber. This is for a very good reason. United Nations statistics show that there are one million people moving into cities every week across the globe. Now is the time to rethink the way cities are planned, built, lived in and maintained. New products, construction methods, technologies and innovations are vital to sustaining this growth. These innovations must also meet the growing demand for wellness, a high quality of life, connection to nature and the environment around us.

Mjøstårnet, Brumunddal , Norway, is now the world's tallest timber-structured building. © Moelven -- Nina Rundsveen

At the same time, the planet is rapidly experiencing climate change, and every indication is that there is an urgent need to slow the rate of planetary warming within less than a decade to avert catastrophic consequences, especially as concerns coastal cities (IPCC 2018). The cities we build today urgently need to achieve net-zero carbon emissions wherever possible, at both the building and urban scale. Both operational and embodied carbon emission reductions need to be a part of this equation. Timber is an excellent store of embodied carbon, and its production process is less environmentally harmful than that of concrete or steel. In the next few decades, the aesthetic and positive health benefits of wood as a material, the ease of construction, its versatility as a structural and finished interior material, and its lower carbon footprint, are likely to overcome current obstacles, mostly based around fire codes predicated on “stick”-framed dimensional lumber construction. For many ecologists, architects and developers, that obstacle cannot be overcome too soon.

Smart-Tinting Glass

Smart-tinting glass blocks solar heat, eliminates glare, provides privacy, and reduces energy consumption by up to 20 percent. © Halio Glass

Glass windows were invented to give people more natural light and a connection to the outdoors. Shades were invented to block that light. A 1,000-year struggle of having too much or not enough light ensued. With smart-tinting glass, the struggle may finally come to an end. Think of it as sunglasses for your buildings. A new type of glass automatically tints when the sun gets a little too hot or a little too bright—letting in plenty of natural light, while keeping people comfortable and making buildings more energy-efficient. Smart-tinting glass blocks solar heat, eliminates glare, provides privacy, and reduces energy consumption by up to 20 percent. Every 30 seconds, the panes, inlaid with invisible intelligence, conducts a daylight analysis to determine whether or not to tint, and by how much. It even factors room occupancy status into its decision-making, choosing the most energy-saving tint level accordingly. Fifty years from now, we won't remember when windows didn't self-tint.

Digital Cities

Artificial Intelligence
Artificial intelligence (AI) is an umbrella term for the theory and development of computer systems able to perform tasks that normally require human intelligence, such as visual perception, speech recognition, decision-making, and translation between languages. There are many ways in which this could manifest in the built environment, particularly when it comes to navigation by autonomous vehicles, creation of complex forms, and predictive modeling of the effects of architectural or urban design interventions (MIT Media Lab 2019). As computing power expands and timescales for significant urban interventions narrow, we can expect that AI will be used much more frequently and effectively in the built environment over the next 50 years.

Smart Cities > Streets > Buildings
As difficult as it is today to avoid the “hype” about “smart” everything, seemingly at every scale, tomorrow it will be just as difficult to distinguish “smart” technology in our cities, streets and buildings, because they will be so integrated into daily life that they will serve a function akin to the human body’s “autonomic” activities, like breathing. According to the CTBUH Technical Guide Smart Technology for High-Rise Buildings, “a smart building is a physical and digital platform which gathers, manages, and acts on data to enhance building performance, with a goal of promoting comfort, productivity, health and sustainability. A successfully realized smart building not only increases the value of the physical asset, but the value of the people who occupy it.”

Quayside, a "smart" district being developed in Toronto, features numerous strategies for weather protection and safety, as well as a system of tubes and tunnels to remove waste discreetly. © Sidewalk Labs

The world has already seen modest deployments throughout buildings and cities, such as occupant-sensing building systems that switch off lights or conditioning when they’re not needed, congestion zones that change pricing according to traffic levels, and huge arrays of sensors that report the status of utilities and services. The information these systems create allows governments and utilities to better target scarce resources to citizens where they can have the best impact. But what’s just a few years around the corner, let alone 50 years from now, is much bigger than that. For example, Sidewalk Labs, a sister company of Google, plans a 4.8-hectare community in Toronto called Quayside, which is expected to have an underground pneumatic tube system for trash removal, sidewalks that heat up to melt ice, and delivery robots. In order for this city to function properly, it will need to collect large amounts of data, “tracking everything from which street furniture residents use to how quickly they cross the street” (Marshall 2019). This type of fine-grained surveillance is controversial in societies with strict privacy laws and protections for civil liberties. Any truly successful “smart” city will need to take account of societal differences; even if “smart” solutions will be ubiquitous, they will not always collect the same data or perform the same functions from place to place. Rather than a “one-size-fits-all” solution, it’s more likely that there will be many customized solutions.


Energy Storage
Energy storage will enable the movement to 100-percent renewable resources. Currently, in order to meet constantly-fluctuating energy demand, power companies must use some form of fossil fuel (typically natural gas or coal) to make up the difference between other energy generation methods and the level of demand. With both wind and solar being dependent on fluctuating conditions, a method of storing the energy will be needed to bridge the differences in demand and creation. There is a whole range of possibilities, from batteries to compressing air into emptied natural gas chambers. In the future, there likely will be more reliable batteries, or a new technology that would increase storage efficiency. Scaled up, storing energy until it is needed would facilitate the end of fossil fuels for energy generation. This would be a significant step to improving the quality of air in cities, especially those in areas that are near coal plants. It could also empower more buildings to include energy generation on their own property or exterior, rather than relying on the existing network.

The Net Carbon-Negative Tall Building
There is great potential for the built environment to move from being a major source of carbon pollution, to becoming net-carbon-neutral at minimum, and, a step further, a “carbon sink.” As the architecture, engineering, and construction (A/E/C) industry embraces this challenge, new material and design innovations will fundamentally change our current thought processes on how we design, build, and operate. “Skyscraper 2069,” the figural carbon-negative tall building of 50 years in the future, will be a showcase of these net-zero to carbon-positive innovations, brought together within one project, and providing a road map to a more sustainable built urban environment of the future.

The innovations needed to create Skyscraper 2069 are many. But it is the details and composition of the materials with which we chose to build with will be most impactful. As the introduction of steel made the tall building a reality, the next most-influential urban intervention will be at the level of materials, fundamentally altering the building blocks we use to create the built urban environment. The Skyscraper 2069 project will include materially-efficient carbon-storing materials, including carbon-neutral steel, aggregate from the manufactured byproduct of carbon-capture scrubbers, carbon-positive bio-based cements, bio-based floor systems made from a composite of bamboo and concrete, carbon-capture graphene in window mullions, and bio-based finish materials (carpet and wall board), all part of a “circular-economy kit of parts.” It will also engage with passive energy generation systems, embedded into the tower façade.


Energy-Dissipating Devices (Dampers)
Small land plots, together with other site constraints, are common in all major cities around the world. The common response is to build as tall as possible, to achieve the highest amount of habitable area, which could be further limited by local regulations and engineering constraints. On especially narrow lots, today’s demands on tall towers with high slenderness ratios have significantly increased, compared to the past 50 years. We are now moving into the age of the “super-slender tower.” Future tower development in major cities may not be exceedingly tall, but will surely be very slender. Energy dissipating devices and dampers play an important role in overcoming such challenges when seeking tower slenderness. Such equipment can potentially create more opportunities to develop optimized solutions on some land plots that would otherwise go undeveloped.

The viscoelastic coupling damper (VCD) can be set within partition walls, so no leasable space is sacrificed. © Kinetica

The increasing demand for developing super-slender towers will help to drive innovation in dampers. Future dampers are expected to be smaller with higher performance, compared to prevailing tuned mass damper (TMD) and tuned liquid damper (TLD) technologies. Among the more promising solutions is the viscoelastic coupling damper (VCD), a high-performing distributed damping system that adds damping to buildings without taking up usable space. VCDs are configured in place of structural elements in typical tall building structural configurations, such as coupling beams and outriggers. The VCDs utilize high-performing viscoelastic damping material bonded between steel plates. As the building deforms due to lateral loads, the dampers deform, adding instantaneous damping to the structure. As buildings are built taller and slenderer, they become increasingly sensitive to both wind and earthquake vibrations. The VCDs are extremely efficient in reducing lateral loads because they directly add damping to the structure which is the most important structural characteristic for tall building dynamic response. Configuring VCDs efficiently in the building structure, reduces wind and earthquake loads resulting in more cost-effective designs, improved human comfort and reduced damage from extreme earthquakes.

Gravity-Load Pre-Stressing
An emerging innovation in structural engineering, gravity-load pre-stressing, has the potential to change the way, and the amount of time it takes, to build skyscrapers. In essence, vertical loads on a building’s floors can be used to reduce or remove the load of the floors themselves. In other words, the floor dead and live loads can be redirected in the opposite direction to “push up” on the floor, rather than down. The closest analog is pre-stressed concrete. However, this system doesn't use concrete, and the method of prestress is entirely different. The advantage of the approach is to significantly reduce the amount of structural material required in floors. By using the force of the live or dead load as its own prestress, a radical improvement in structural efficiency is possible. This would have a compound effect on the sizing of columns and foundations, as well as reducing the carbon footprint, cost of construction, time to build, etc.

The innovation was developed as part of a package of conceptual changes to the common practices of structural engineering. A key principle of this approach is to make buildings much more efficient, thereby reducing their mass. That allows a different approach to design and construction; specifically, much faster construction is feasible, at lower cost, and with a lower environmental footprint. That will change how, where and when structures are built. A tall building that currently takes a couple of years to build, might be finished in less than half the time. For cities in developing economies, it could allow for faster, most cost-effective vertical expansion of cities. It could also reduce the mass of the materials used in construction. Heavy steel and concrete elements could be replaced by lighter-weight materials. This innovation could also catalyze design change; and taller buildings might be feasible as a result.


Autonomous Vehicles

Self-Driving Car for Yandex Taxi in Las Vegas. © Екатерина Волкова (cc by-sa)

Self-driving vehicles have already been tested on roads for several years, with varying levels of success, but it seems relatively certain that autonomous cars will be an increasing presence in future cities. Door-to-door transportation that can safely move people without requiring their continuous attention has the potential to radically alter the topography of cities. The vast amounts of parking and road infrastructure that now take up as much as a third of surface area in some cities could be significantly reduced if the huge margins of space required for human reaction time (such as the need to maintain braking distance between cars, or the amount of on-ramp needed to join or leave a highway) could be replaced by pinpoint-accurate tolerances. Likewise, if most vehicles are no longer privately owned and used for one or two journeys per day, but instead function more like taxis that can be called into service at a moment’s notice, there would be much less need for parking spaces, lots and garages. The saved space could be converted back to pedestrian streets, parks, and housing, for example.

Bicycle Superhighways

RS1, Ruhr, Germany, is a vision of a bicycle superhighway, infrastructure that may become more prevalent in the near future. © Der Regionalverband Ruhr (RVR)

Many cities have some form of bicycle lane, but few major cities have dedicated bike superhighways, which are designated for long-haul bike travel, and largely devoid of traffic lights or crosswalks, just like highways designed for motor vehicles. This type of transportation network can already be found in places such as the Netherlands and Denmark, but the future will see bicycle superhighways become more widespread, creating a radical shift in not only fossil fuel emissions, but also in the traffic congestion that plagues most modern cities. Another benefit of dedicated bicycle superhighways is the allowance for high speeds while drastically reducing the number of cyclist-vehicle collisions. Commutes will become much more enjoyable, as commuters turn away from stagnant car traffic to a form of transportation that allows them to exercise and clear their minds, both to and from work. Happier commuters could increase citywide productivity by increasing fitness levels, as well as exposure to the outdoors, which numerous studies have shown has a lasting effect on human wellness.

Drones and “Flying Taxis”
Unmanned, autonomous flying vehicles, or drones, are in frequent use by militaries and hobbyists, and in some remote locations, already deliver small packages. Given that airspace is crowded already, and highly restricted, successful deployment of drones for everyday activities—especially if carrying human cargo—will depend on a high degree of coordination between aviation authorities and public and private transport operators. Nevertheless, cities from Dubai to Paris are readying infrastructure for flying taxis in as little as five years (Samuel 2019). Depending on the size and maneuverability of the vehicles, there may be some noticeable changes to the design of tall buildings in the near future, so as to accommodate mid-tower or rooftop landings. Already, apartment towers with balcony inlets for drone deliveries and numerous Uber “Skyports” (replacing parking garages) are on the boards (HPA 2019; BBC 2019). If this trend “takes off” as advertised, expect to see more net reductions in paved-over urban space (see also “Autonomous Vehicles”).

Anticipating the near future of flying and autonomous cars, an Uber Skyport has been proposed for the Dallas area. © Greenfield

Elevator Advances: Carbon-Fiber and Ropeless
The disadvantages of existing steel-rope-hoisted elevators, including high energy consumption, rope stretch, large moving masses, and downtime caused by building sway, are well known. Two solutions have been proposed in recent years, and are likely to gain traction in the near future.

Left: UltraRope, a carbon-fiber and epoxy-based product, is a fraction of the weight of a traditional steel-cored hoisting rope caption. © KONE; Right: MULTI is a multi-directional, ropeless elevator that uses linear-induction technology similar to that of magnetic levitation (maglev) trains. © thyssenkrupp

Carbon-fiber rope, which is surrounded by a high-friction coating is highly resistant to wear and abrasion. With an elevator travel height of 500 meters, carbon-fiber rope can cut the elevator’s moving mass by 60 percent and reduces energy consumption by 15 percent. For an elevator with a travel height of 800 meters, moving masses can be reduced by 90 percent and energy consumption by 45 percent.

Ropeless, linear motor elevator technology can move multiple cars in a single shaft, both vertically and horizontally. This can increase passenger throughput by 50 percent by enabling multiple cabins to travel safely up one shaft and down another in a single continuous loop. At the same time, the elevator footprint in a building can be reduced by up to 50 percent, providing further usable floor space and revenue to building owners. The recent CTBUH Research Report, Ropeless Elevator Systems, compiled some of the most practical and exhilarating possibilities for the technology.

Hyperloop / Extreme High-Speed Rail (HSR)

Shanghai Maglev Train connecting the Pudong Airport with the city. The linear-induction technology used on the maglev, which can achieve speeds 400 km/h, has now been applied to elevators; future trains may operate in vacuum tubes at even higher speeds. © Andreas Krebs (cc by-sa)

Conventional high-speed rail trains now achieve sustained speeds of 250 kph, and in places such as China, have collapsed intercity travel times from days to hours, tremendously increasing opportunities for the exchange of people and ideas. The introduction of trains running in tunnels vacuumed of air resistance, such as the Hyperloop, allow for significantly faster travel, up to 1,200 kph, that could effectively compete with air travel. This could have similar effects on a higher order of magnitude, potentially replacing air travel on some journeys, taking up far less space, using less energy and producing less pollution, while still providing similar transit times. If scaled effectively, a global network of high-speed tunnels could have radical implications for increasing city density and reducing sprawl.

Ride-Sharing Platforms
Smartphone-based applications pair passengers with drivers, reducing the need for personal vehicle ownership in dense urban environments, particularly areas with limited public transportation facilities. These vehicles will eventually become driver-less/autonomous and this, coupled with 5G and 6G high-speed mobile phone connections, will enable cars to move through dense urban habitats much more efficiently than is currently possible today. In addition, as the need for personal vehicle ownership is reduced, the amount of necessary on-street parking spaces will be significantly reduced accordingly, thus enabling cities to "reclaim" street area previously used for parking vehicles. Expect this technology to take on new dimensions in future cities, as autonomous vehicles and flying taxis become more commonplace. Further integration with other emerging.

1 The submissions ultimately accepted for publication were sent by: Wolfgang Adldinger, AD LIFT Service, Augsburg; Mehdi Ashayeri, Illinois Institute of Technology, Chicago; Aric Austermann, CTBUH, Chicago; Iraklis Chatziparasidis, Kleemann Complete Lifts SA, Kilkís; Allen Dusault, Dusault Engineering, Mundelein; Tim Ebeling, Henning GmbH & Co. KG, Sarstedt; Yuko Endo, Nippon Lifts Engineering Inc., Yokohama; Abdul Fattah, Cairo University, Cairo; J.R. Freeman, Henning GmbH & Co. KG, Spring Branch; Jayme Gately, Hoerr Schaudt Landscape Architects, Chicago; Alicia Gay, Vision Elevator Componenets & Solutions Provider Pte Ltd, Singapore; Aleksey Gorilovsky, Stein Ltd., Los Angeles; Kevin Heling, Wurtec Inc., Whitby; Hugh Hunter, Wurtec Inc, Whitby; Hermann Kamte, HKA | Hermann Kamte & Associates, Yaounde; David Kaphingst, OV Equipment, LLC, Tucson; John Koshak, eMCP, LLC, Reno; Eveliina Linderborg, KONE, Espoo; Ai Matsumura, Nippon Lifts Engineering Inc., Yokohama; Nishant Mukeshbhai Kansagra, Ienzigartig Sthapati Building Workshop Pvt. Ltd., Amsterdam; João Paulo Lopes, Wurtec Inc, Santo Andre; David Malott, AI., New York; Michael Montgomery, Kinetica, Toronto; Rolf Muller, Nippon Lifts Engineering Inc., Yokohama; John Mylonas, Helcoma Hellas Ike, Athens; Myrna Nickelsen, Kinestral Technologies, Inc., Pinole; Ted Parisot, Helios Visions, Chicago; Jonathan Schifman, Skidmore, Owings & Merrill LLP, New York; Kate Simonen, MKA/UW/UC Boulder Collaboration, Tacoma; Eisaku Takada, Nippon Lifts Engineering Inc., Yokohama; Emily Torem, CTBUH, Chicago; Assawin Wanitkorkul, Aurecon, Singapore; Ted Watson, MJMA, Toronto; Chris Williamson, Weston Williamson+Partners, London; Ai Xia, CCDI, Shanghai; Hiroyuki Yagi, Nippon Lifts Engineering Inc., Yokohama; Roberto Zappa, Zetaplan, Monza; Stefano Zucca, Sematic, Olgiate Molgora


BBC. (2019). “Uber Takes Its Flying Taxi Ambitions to Australia.” BBC, 12 June 2019. Accessed 25 June 2019. https://www.bbc.com/news/business-48604495.

Humphreys & Partners Architects (HPA). (2019). “Uber Elevate 2019. Volary: Our On-Demand Aviation Community.” Accessed 25 June 2019. https://humphreys.com/uber-elevate-2019/.

Intergovernmental Panel on Climate Change (IPCC). (2018). Global Warming of 1.50C. Geneva: IPCC.

Marshall, A. (2019). “Alphabet's Plan for Toronto Depends on Huge Amounts of Data.” Wired, 24 June 2019. Accessed 25 June 2019. https://www.wired.com/story/alphabets-plan-toronto-depends-huge-amounts-data/.

MIT Media Lab. (2019). “Deep Image of the City.” Accessed 25 June 2019. https://www.media.mit.edu/projects/deep-image-of-the-city/overview/.

Samuel, H. (2019). “‘Flying Vehicles’ Could Hit Paris ‘Within Five Years’ Says French Capital's Public Transport Operator.” The Telegraph, 19 May 2019. Accessed 25 June 2019. https://www.telegraph.co.uk/news/2019/05/16/flying-vehicles-could-hit-paris-within-five-years-says-french/.