Today, half of the world’s population lives in cities. By 2050, that number is expected to increase to two-thirds. More people living in condensed areas means higher amounts of waste, higher resource consumption and higher energy use. As the world’s cities already emit over 70% of carbon emissions, exacerbating the climate crisis, cities need to implement green infrastructure to meet these challenges.
In response to these issues, some city planners and developers have started to become inspired by the circular economy. Circular economies seek to redefine growth through society-wide benefits, incorporating environmentally friendly practices that include minimizing waste and pollution, capitalizing on sustainable resources and the regeneration of natural systems. The goal is to achieve sustainability through renewable resources and zero waste.
These same ideas can be applied to the design of cities and infrastructure, too. In fact, some major cities are already starting to incorporate more natural and sustainable initiatives to combat waste and unsustainable policies. NYC and Copenhagen are among the list of urban hubs applying circular economy tactics to the urban environment, earning them the apt title of “circular cities.” I’m proud to be a part of this trend, too — as president of a New York condominium, my building is the nation’s tallest residence with a solar array, which supplements power to residents and reduces our carbon output by over 125,000 pounds annually. We have also gone through green upgrades including sensors that allow for savings on energy and a reduction in greenhouse emissions.
For cities and properties that intend to stay livable into the foreseeable future, these circular operations are quickly becoming less of an option and more of a necessity. Without them, high waste volume and unsustainable resource consumption threaten to destroy the environment and the very cities we live in.
Green Design Mitigates Waste
Designing a truly circular city means building infrastructure that minimizes the negative effects on human health and the environment and solves numerous problems, including stormwater management, heat stress and pollution. Traditional roofs and exteriors are problematic from this perspective because they allow oil, pesticides, chemicals and even animal waste to simply flow freely into waterways, causing pollution and increasing the chances of human infection.
But green roofs and facades — completely or partially vegetated roofs and building exteriors constructed on top of layers of soil and waterproof filters — include drainage and irrigation systems that are crucial to a circular city’s ability to mitigate that waste. Green roofs absorb a significant amount of rainwater, helping to mitigate overflow-induced toxin spills. Plus, green roofs last longer and are proven to divert waste from landfills by saving on HVAC maintenance costs.
Stormwater Becomes A Resource
While roofs and facades can play a key role in the management of toxic stormwater, they mainly recycle water to feed gardens and save on utility bills. Other infrastructure projects can also manage and recycle toxic runoff, but for a different cause: using stormwater to improve the water supply for municipal and citizen needs like offering clean water for flushing toilets or even drinking.
In this case, green infrastructure acts like a sponge, absorbing and reducing the amount of contaminated runoff into natural bodies of water and redirecting it to be recycled for community purposes.
Brooklyn’s “sponge park” is cleaning up the long-polluted Gowanus Canal using a special soil that absorbs and filters runoff through a series of screens that then release the purified excess into waterways and water systems. Similarly, China’s “sponge city” initiative helps cities absorb rainwater, reduce flooding, ease pressures on municipal treatment systems and increase their water supply. Recycling runoff mimics nature’s own circular way of dealing with rainwater, offering a cleaner and more holistic approach for growing cities.
Berlin’s Potsdamer Platz is another prime example. Rather than a sponge system, the urban pools take advantage of an interconnected system of green roofs, urban spaces and a constructed treatment pond to recycle and filter excess stormwater for irrigation and indoor plumbing. Another project, Bo01 Development in Malmö, Sweden, handles and treats all stormwater to power a system that creates 100% renewable energy. Using stormwater to power buildings and supply water lets cities and property owners reduce fossil fuels and save money.
Green Design Saves Energy
To curb emissions that contribute to climate change, cities must also curb their energy usage. In the United States, 40% of total energy consumption comes from buildings, which emit over one-third of global greenhouse gases. However, one study found that green buildings use, on average, 30% less energy than conventional ones.
The same green roofs and facades used to mitigate toxic rainwater also protect against extreme temperatures, both reducing heat (and the need for air conditioning) in the summer and increasing temperatures in the winter so citizens can save energy and limit carbon emissions. A green roof even reduces summer energy demands by 75%. Additionally, renewable energies employed by green buildings can cut 90% of energy-related carbon emissions rates.
Today, over 100 global cities boast a 70% carbon-free green energy plan. Some, like Chicago, are making commitments to reach 100% by 2035. Other cities like NYC are stepping up their game with green roof legislation, requiring certain buildings to outfit their roofs with vegetation and renewable materials like solar panels.
While no city is fully circular yet, the most forward-thinking city planners and developers are increasingly using green designs in their infrastructure projects. With the climate crisis looming, now is the time for us all to support circular initiatives, assessing and updating aging infrastructure with green resources. If cities proactively use circular infrastructure to limit waste, save energy and improve their resources, we could protect our cities and their growing populations — before it’s too late.