How urban sustainability will improve cities, economies, and the world

Urban sustainability can mean a lot of different things. Simply put, a sustainable urban area is one that aims to improve the social, economic, and environmental conditions of a city to ensure the quality of life and well-being of current and future residents and visitors.

Perhaps more crucially, the concept recognizes that every facet of city living—employment, transportation, food, health, the economy, and more—influences the others, so all areas must be designed and implemented with those network effects in mind.

Creating sustainable cities requires agreed-upon specifics. Solutions need to be scalable without upsetting the established balance. It’s necessary to define exactly where a city’s boundaries are, conceptually and geographically, and select robust indicator signals to decide where the priorities lie. And all this needs to be accomplished in cities that are hundreds or even thousands of years old—and where unsustainable systems are deeply entrenched physically, economically, culturally, and politically.

Designing greener, livable, self-contained cities is a win-win, benefiting the people who reside and work in them while also benefiting the surrounding environments. Some of the most visible and immediate advantages will be:

Environmental, transportation, and energy wins

Decarbonizing cities is critical. Funding transportation that isn’t based on fossil fuels and providing more green spaces to encourage plant and animal life back into cities, prompting a return to native biodiversity, lets city dwellers live cleaner lives that are more closely connected to nature.

Many cities are already transforming transportation systems by closing streets to cars and installing electric trams with stops close to commercial, retail, and residential hubs. This process doesn’t need to be high tech: Taking 50 cars off the road in favor of a single bus reduces congestion, air pollution, and fossil-fuel use. This action can free up space to remake better mass-transit systems and create bicycle lanes, parklands, and natural domains. There’s already a successful precedent in Manhattan’s High Line.

A boost to public health, food production, and green spaces

Illnesses and stress imposed by work structure, badly planned commuting systems, and disconnection from the Earth cost economies billions. The mental-health benefits of exposure to nature are beyond debate, and people will be happier (and therefore more productive) in sustainable urban environments.

Urban farming systems such as rooftop gardens reduce reliance on far-flung mass producers, dramatically improving farm-to-table ratios and reducing costs like transport industry emissions. (Rooftop farms also mitigate the urban heat island effect and absorb stormwater runoff, a major cause of urban flooding in response to exceptional rainfall events.)

One hallmark of urban sustainability is doing more with less. To find land for more green space in the average city, look to reclaiming it from outdated systems or using redundant space in and around buildings. Creating ponds and gardens that encourage animals to return is just the beginning; big cities also have acres of unused space in full sun (or rain) on their rooftops. What better place for urban farms?

A shift to circularity

Many scholars think of waste as “resources out of place.” Nature is a perfect recycling engine, and humans can emulate it by designing systems that deliver process outputs directly to the next system as inputs.

One example was the 2021 Tokyo Olympic Games’ plan (p. 9) to reuse or recycle 99% of goods procured and 65% of waste generated. Only eight of the 43 competition venues were built from scratch. Materials, like the wood for the Olympic Village Plaza, were donated by local government and returned or used in other public infrastructure projects afterward. The majority of goods were also procured in lease or buyback schemes with producers.

Cities are like human bodies. Each one is an organism in which nothing happens in a vacuum, and every policy in transport, climate change mitigation, and parkland planning affects the rest. After food or supplies are bought into urban environments, the waste is pumped, shipped, or plumbed out at even more expense because of the need for sewer systems or fleets of sanitation trucks. In other words, city takes from the world around it and gives little back.

In a circular economy, as much as possible, whatever is done or used in a circular city stays there, powering that city from within with systems designed to reabsorb outputs.

Here’s a radical first step toward shifting to circularity: Create an authority with real power over sustainable city planning. Departments that supply water or manage garbage or sewage currently have clear parameters, beyond which everything is someone else’s problem. A data-driven, bird’s-eye view will show that every car in and bag of trash out is everyone’s problem.

The first step toward urban sustainability is deep planning. Every action and system has to be designed to work seamlessly in concert with the others to maintain the correct balance.

But doing so is made exponentially harder by one glaring factor: These cities are already built. Many of the necessary actions involve remaking existing buildings, networks, and ways of living and working—any changes must be thoroughly systematized and simulated. Of course, the community also has to be onboard.

The most visible example of undoing a deeply entrenched urban practice is removing cars. The postwar years saw cities expand around the private automobile, and as long as public transit fails to offer the same comfortable and personalized door-to-door convenience, its adoption faces an uphill battle.

Retrofitting costs need to be considered, and in areas that will see significant inconvenience and stress, the needs go deeper than financial spending. But planning urban public works with a “sustainability first” stance is the only way forward, and the tools and platforms that will help are already widespread.

Building information modeling (BIM) is one tool. Whether for a new or existing building, BIM is key to generating a digital twin of the asset—not just floorplans from architectural drawings, but the entire ecosystem: lighting, heating, cooling, and fire-fighting systems; foot traffic patterns captured by security footage; and so forth. A digital twin creates a real-time, virtual representation of the building, customizable by connecting datasets or analytics to report on every possible aspect of use and systems efficiency. Planners can run analysis and predictions that let them make smarter, more informed choices throughout design and construction and, ultimately, operations.

Imagine a corridor that’s barely used after most people have arrived at work. One solution could be programming a motion-detector-driven lighting system that shuts the area’s lights off when people aren’t present. Or an Internet of Things–connected HVAC system could synthesize data from sensors in lights, vents, and thermostats located throughout an office building, as well as energy inputs from the local grid, occupancy awareness, and even weather data from outside. A human controller—or even machine-learning agents referring to historical usage data—could then issue adjustments to optimize a building’s lighting, heating, and air-conditioning needs, down to individual rooms and areas.

These types of small changes can be scaled up to every system in a building. The next step is connecting metrics on every building or block in a vast, cloud-based data set to create a constantly updated, real-time view of environmental, cultural, financial, and resource use. From there, you can design a sustainable city using hard data instead of guesses.

Methodologies and platforms to combine, measure, and report on BIM results already exist. Recognized urban sustainability indicators include greenhouse-gas emissions, waste volume, and so on. The platforms that synthesize them help city managers project how these metrics will change across space and time to figure out how they'll interact—from the lifecycle of a single building to population or demographic shifts.

Building the future

Every day, at least 200,000 people pack their bags and move to the big city. By 2050, almost 70% of the world’s population will live in cities—that’s about 7 billion people.

The built world already uses up to a third of extracted natural resources and generates a quarter of all solid waste.

To make sustainable cities possible, construction has to change. Models to build better are becoming widespread—they just need to take hold in economies and legislation. They include:

• Low-carbon development, which aims to reduce material inputs, defects, and material waste.

• Prefab/modular construction, where buildings are manufactured in pieces off-site and shipped and assembled on-site, reducing material needs and local disruption and increasing safety.

• Building information modeling, where a digital rendering of a project and all its needs, processes, and uses can be tested and improved to find the most sustainable plan before building begins.

Building for resilience

As the effects of climate change continue to worsen, disasters keep getting more destructive, costlier, and more deadly. In 2022, 18 climate-related disasters caused more than $1 billion worth of damage in the United States alone.

Resilient cities promise less physical, environmental, and social damage from calamities. Recovery will be faster, and services crucial to rebuilding, such as health and education, will be maintained. According to a 2018 National Institute of Building Sciences report, every $1 spent on disaster mitigation could save $6 in the future.

If you’re designing a building, you can use BIM to test its resilience. Plenty of platforms can put your model in a virtual wind tunnel or earthquake zone and give you real, actionable data about where you need to make changes. Or think about how sea-level rise will potentially displace millions. Can you design better ways to fortify coastal buildings and urban systems now? And if there is a catastrophic flood because of heavy rainfall or a broken levee, simulations can determine where stormwater will flow; which evacuation routes to maintain; and which critical infrastructure to fortify to keep hospitals, power, and other infrastructure running,

After the planning and projections are done, it’s time to put it all to work. Property developers did just that in Miami’s Coconut Grove district with Grove Central, a residential and retail complex designed using urban sustainability principles to make pedestrian flow as efficient and pleasant as possible.

A notoriously crowded city with high car traffic, Miami was the perfect place to put urban sustainability to the test. The designers behind the complex had two goals: to create a community-minded space where amenities are all within walking distance and to make it easy to get to other places in the city, particularly via a direct connection to the subway system.

The entire project was modeled virtually, using Autodesk Revit to optimize approaches from other transit systems into the complex. Removing cars from the complex reduced pollution, and an energy-efficient facade cut down on heat from the sun while maximizing natural light. The BIM data was shared with mechanical and electrical engineers to ensure the most efficient, environmentally friendly materials selection and electrical-system arrangement.

So far, residents and businesses love it. Car noise and pollution are a thing of the past and residents can go everywhere on foot, which fosters a sense of community.

But using BIM is only the beginning. Imagine if you could walk through your design in a completely digital world, making notes, taking measurements, and seeing what works, just like in many virtual reality (VR) games today. Now imagine doing that for a whole industrial complex or parkland, maybe an entire urban area.

Well, you can. Infrastructure consultancy WSP Opus and digital creative agency Method, both from New Zealand, created Sustain-a-City, a VR game where you can build your own city by balancing commercial, infrastructure, energy, and residential elements. Think Sim City, except you’re in it.

WSP Opus knew that city planners usually commission and deploy urban infrastructure piecemeal, as budgets allow, only thinking about connecting it to other services down the track. Sustain-a-City was created to encourage an understanding of what’s involved in building a real-life sustainable urban environment. It lets players connect water and power, plan residential housing and commercial real estate, and install transport, letting the city grow while aiming to keep every element balanced and friendly to the environment and inhabitants. Its creators think VR is the perfect medium for this exercise.

This is just one example of ways technologies such as VR and augmented reality (AR) are being used—and will be used in the future—to bring urban design to life, bringing it off the plans and putting it in front of users.

Beyond that, geographic information system (GIS) mapping places construction project models in the context of the local environment provide the ability to connect to broader data sets such as local climate, information, road traffic systems, and power and waste inputs and outputs, giving planners even more information to best simulate and design systems in BIM models.

Humans haven’t even come close to matching the efficiency at which nature repurposes matter. But it’s important to focus on the net effect, a practice that fomented environmental movements such as planting a tree for every plane trip taken.

To approach sustainability, several components have to line up. The first is technology: It’s now possible to digitally model and plan urban sustainability as many times as necessary, iterating again and again until it’s ideal.

But maybe more important is the willingness to change. Thinking like a community requires sacrifice and inconvenience while things are rebuilt and reconfigured, using public and private spending to benefit the greater good.

Take another look at Miami’s Grove Central. A city notorious for its overuse of cars seemed like the last place residents, businesses, and the city government would try something so culturally alien. But it’s working there, so it may be possible anywhere.

This article has been updated. It originally published April 2019. Taz Khatri and Rina Diane Caballar contributed.