For the rest of this century, humankind will be building cities at an unprecedented pace. The world population is projected to increase from 7.9 billion to more than 10 billion, and much of that increase will occur in parts of the world that lag in infrastructure. Everywhere, people will expect to catch up, and then surpass. China is a fantastic example of how this can happen in just 30 years.
But there are two other factors that will supercharge the building boom. A large proportion of the people who now live in rural areas will move to cities, just as happened over the last century in North America. That will not only swell the populations of existing cities, it will also create new ones. Concurrently, rising sea levels caused by climate change will swamp many coastal cities throughout the world, forcing them to rebuild parts of themselves on higher ground. Cities including Boston and New York are already spending substantial sums on projects to hold back the sea, which has begun encroaching in subways and road tunnels over the last 10 years. But that is just a small precursor of what will come.
One problem with our current building methods is that they have a high carbon footprint, meaning that the act of building will increase the need for yet more building. Fortunately, construction technologies have been advancing over the last 20 years and we are on the verge of a revolution.
Many of the construction techniques we use today were invented in ancient Egypt or Rome. Examples include concrete, the weighted plumb line to determine true vertical with a square to derive the horizontal from that, and snapping a taut chalk-covered string on the ground to lay out a straight line for a wall. The arch, developed by the Romans, has been superseded by steel beams for the transom over windows and doors, and now digitalization is encroaching on these other time-tested techniques.
Simultaneous localization and mapping (SLAM) was developed in the 1980s and used originally to enable indoor robots to map their surroundings and locate themselves within them, using cameras, lidar, and other sensors. It is now used on construction sites to reconstruct a full three-dimensional model of an environment, just by walking around with one of the latest smartphones, which incorporate depth sensors. These techniques allow the dimensions of partially constructed buildings to be uploaded to CAD models, and then use augmented reality to show workers exactly where to place the next components. Larger and larger components of new buildings are being built offsite in factories, making construction more efficient and less labor intensive.
Many of the techniques we use during construction today were invented in ancient Egypt or Rome.
Other techniques are changing what we can expect buildings to look like. We are starting to see large buildings with lots of plants as part of the environmental control systems, making city buildings look like living organisms. With vertical farming taking hold, many new buildings in cities will be the source of food grown close to where it is consumed. This is literally green technology.
For thousands of years our buildings have been rectangular and largely built in place by craftsmen. In the second half of the 20th century we began mass-producing small-scale building components. These allowed enormous lightweight curtain walls of identical elements, whether of glass, aluminum, or thin stone, mounted to the structural elements, giving buildings a much lighter and different look. But the identical mounting components meant that rectangular designs were pretty much all that could be produced. Now, with 3D printing along with general-form geometric CAD, new shapes will become possible even for low-cost buildings. And as 3D printing progresses to larger and stronger components, even the structural elements will be freed from the tyranny of perpendicularity.
Combine all these factors and a dazzling possibility emerges. Imagine using cheap wind- and solar-generated electricity to pull carbon out of the atmosphere and turn it into feedstock for large-scale 3D printing of building components. Whoever commercializes that will have a shot at pulling off a remarkable first: building the first megabusiness—and megafortune—that reduces atmospheric carbon rather than increasing it.
This article appears in the March 2022 print issue as “Building Boom.”
Rodney Brooks is the Panasonic Professor of Robotics (emeritus) at MIT, where he was director of the AI Lab and then CSAIL. He has been cofounder of iRobot, Rethink Robotics, and Robust AI, where he is currently CTO.