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During the 2010s, thousands of Rotterdam building owners installed green roofs on their dwellings – about 330,000 square metres in total, almost 2 per cent of the city’s 18.5 square kilometres of flat roof space. But where some cities have promoted such projects to improve energy efficiency and absorb carbon dioxide, Rotterdam’s green roof infrastructure is all about water and keeping as much rainwater runoff as possible out of aging, overtaxed sewers in order to prevent flooding.
About four-fifths of the Dutch port is below sea level. As Paul van Roosmalen, the city official overseeing sustainable public real estate, puts it: ‘The water comes from all sides’: the sea, the sky, the river, and groundwater. ‘It’s always been a threat.’ But he also sees an opportunity to use a marriage of technology and green design to elevate the role of rooftops in managing Rotterdam’s water pressures.
While typical green roofs function like sponges and look like gardens, Rotterdam is working with public and private landlords to develop a ‘green-blue grid.’ Instead of simply fitting out roof areas with plants, these spaces can be equipped with reservoirs or tanks to retain excess flow – blue roofs. The tanks, in turn, are equipped with electronic drain valves that can be opened and closed remotely, in some cases via a smart phone app.
‘The problem,’ says van Roosmalen, ‘is that when they’re full, they’re full.’ The city’s vision, he explains, is to develop a system for coordinating the water levels in these tanks to help manage sewer capacity. The idea is to link the valve control devices into a grid of blue roofs that function, in effect, like a dispersed network of stormwater reservoirs. When there’s rain in the forecast, the reservoirs can be drained automatically. Then, during heavy weather, they can store rainwater, reducing pressure and flooding in the sewer system.
While Rotterdam’s blue-green grid is still far from completion, it can be seen as an example of how a set of digital sensing technologies can be potentially harnessed to produce a smart city solution to an urban sustainability problem.
The technological linchpin in Rotterdam’s strategy has been the installation of highly sensitive weather radar on the roof of the city’s tallest building. The device is capable of detecting rainfall 16 to 20 kilometres away. Remotely operated blue-green roof control systems can be programmed to dynamically respond to those forecasts and release water that sits in the reservoirs. (A similar project, the Resilience Network of Smart and Innovative Climate Adaptive Rooftops, or Resilio, is underway at several Amsterdam social housing complexes.)
As of 2021, Rotterdam officials were testing a pilot version of this grid. To scale it up, the city has to figure out how to coordinate with Rotterdam’s water board, which manages the sewer infrastructure, as well as property owners. The strategy potentially complements other water management planning moves, among them retrofitting public squares with ‘rain gardens’ – i.e., clusters of water-absorbing shrubs and perennials planted in small depressions in the ground. ‘Instead of making bigger sewer pipes, we made a choice to invest in redesigning public space in a way that contributes to a nicer, better, more attractive district,’ Arnound Molenaar, Rotterdam’s chief resilience officer, told Thomson Reuters in 2019.
Van Roosmalen adds that a green roof can absorb about 15 millimetres of rain per square metre, whereas a roof with a reservoir can retain ten times as much. The city’s goal is to convert 1 million square metres of flat roofs to include water retention systems and solar panels. Aggregated across even a portion of the city’s flat roofs, he says, ‘it’s a tremendous amount of water.’
Climate change is, in significant measure, a consequence of the twin historical forces of industrialization and urbanization.
The Industrial Revolution, fuelled as it was by steam- and coal-powered mass production technologies, drew people away from rural areas and small towns and set in motion a complex dynamic that persists to this day. Swelling of urban populations gave rise to poverty, public health crises, and urban pollution, which in turn spurred social reforms, outward expansion of cities, rising incomes, and the commercialization of combustion engines. Mass consumerism and environmental degradation caused by car-oriented sprawl accelerated fossil fuel dependence, plastic waste, and the overuse of carbon-intensive city-building materials, like cement, concrete, and asphalt.
Yet post-industrial cities, with their economies of scale and concentrated populations, have also generated a wide range of sustainable innovations, products, and approaches to planning and development. In some places, these have boosted building energy efficiency, improved air quality, increased transit use, and encouraged nonmotorized transportation. What’s more, some cities, like Vancouver, have stoked the cleantech sector by attracting entrepreneurs, venture capital, and scientists, revealing how urban prosperity can be tethered to the transition to a low-carbon economy.
It’s also true, however, that in the globalized twenty-first-century, the cast-offs of the inhabitants of wealthy, urbanized nations are shipped to vast waste recycling or landfilling facilities in countries like China and the Philippines. And when inexpensive goods produced in the Global South are purchased by consumers in affluent countries, all that transnational trade effectively allows the North to shift emissions, air pollution, and ecological destruction to coal-dependent megacities in Asia and the oceans that serve as the primary means of shipping goods around the globe.
The warming caused by these and other factors is expressed in the form of habitat destruction, melting ice caps, extreme weather, sea level rise, and so on. But some of the most disruptive effects of climate change will be experienced by the inhabitants of low-lying coastal cities like New York, Mumbai, Shanghai, and Rotterdam.
However, even before climate change became a global crisis, the technologies unleashed by rapid industrialization, combined with abrupt spikes in urban population, gave rise to profoundly polluted cities. The dismal air quality in megacities like Beijing and Delhi is lethal; indeed, in the early months of the 2020 pandemic, when car traffic plummeted, the residents of Delhi found they could see the mountains north of the city, which are normally obscured by a dense haze.
These are not new phenomena. The widespread use of low-grade coal for heating, coupled with an atmospheric condition known as an ‘inversion,’ had blanketed London in dense smog for generations, leaving in their wake a residue of grime on both buildings and the lungs of the people who lived with the intensity of the pollution.
One of the ironies of industrial and post-industrial urbanization is that the environmental crises triggered by one generation of technologies has spurred the development of new technologies aimed at cleaning up profoundly polluted cities.
The postwar history of Pittsburgh, Pennsylvania, vividly illustrates that paradox, and the implications for one mid-size city. By the 1940s, Pittsburgh was suffocating on the riches it had generated from its giant steel mills, powered, as they were, by coke and coal from the rugged Allegheny Mountains. Pittsburgh steel had helped create America’s railways and then its booming car industry. The family-run business empires associated with the industry – Carnegie, Mellon, Frick – generated enormous wealth that allowed them to burnish their considerable notoriety with philanthropic ventures that ranged from art and education to the establishment of the modern public library system.
Yet Pittsburgh paid a steep price, with extreme air pollution from smokestack industries and water contamination caused by the dumping of raw sewage into the rivers that run through the city. ‘From whatever direction one approaches the once-lovely conjunction of the Allegheny and the Monongahela, the devastation of progress is apparent,’ according to one early-twentieth-century description cited in a recent journal article by Joel A. Tarr, a Pittsburgh historian. ‘Quiet valleys have been inundated with slag, defaced with refuse, marred by hideous buildings. Streams have been polluted with sewage and waste from the mills. Life for the majority of the population has been rendered unspeakably pinched and dingy. This is what might be called the technological blight of heavy industry’ (qtd in Tarr 2003).
By mid-century, the city’s economic future was in jeopardy, and grassroots organizations were sounding the alarm over the link between air quality and health. ‘The smoke had many devastating effects on the city and the way people lived,’ Tarr wrote in 2003. ‘Some of the most famous were the conditions downtown at midday when street lights had to be turned on.’ He relates how the county moved to impose emission regulations and treat its sewage. But besides tougher laws, technological innovations – smokestack scrubbers, the rapid conversion of coal-burning locomotives to diesel, and the adoption of natural gas for home heating – ultimately drove improvements in the city’s quality of life.
Urban scholars also point out that the story of Pittsburgh’s rebirth as a post-industrial tech hub can be traced to a critical decision by municipal leaders in the 1940s and 1950s. Recognizing that they alone couldn’t save the city, those officials decided to make common cause with a new civic group called the Allegheny Conference on Community Development. A coalition of business leaders, universities, and other agencies that coalesced in the 1940s, the Allegheny Conference not only supported air quality measures but also sought to figure out how to ensure the city’s survival in a post-smokestack world (Allegheny Conference on Community Development).
Over the coming decades, it helped attract new non-industrial development, supported moves to improve public transit, foster cultural activity, expand the scale of the cleanup of the region, and promote higher education and research-focused institutions, such as Carnegie Mellon University. In recent years, CMU has attracted scientists and tech entrepreneurs, emerging as a centre for R&D focused on autonomous and electric vehicles, as well as energy.
Indeed, Pittsburgh is generally regarded as the most successful of the so-called Rust Belt cities in the U.S. and has been cited by urban geographer Richard Florida as an example of the so-called ‘creative class’ approach to urban revitalization.
Some of the earliest applications of the smart city technology being created in places like Pittsburgh involved sustainability – and specifically distributed, renewable electricity. Conventional electricity grids were linked to large, and often dirty, power sources: coal- or gas-fired generators. But in the early 2000s, as wind power and solar became more economically viable and politically popular, governments ordered public utilities to figure out how to allow smaller and more localized sources of power generation to access the electricity grid. These included homes or flat-roofed commercial buildings with rooftop solar panels that could generate energy.
In Ontario, the provincial government’s 2007 pledge to phase out coal forced a push for renewable alternatives. Inspired by a German policy approach to incentivizing investment in clean electricity (the so-called ‘feed-in tariff’), Ontario sought to attract sustainable energy investors, large and small, with attractive subsidies guaranteed over twenty years. Besides these financial incentives, the transition turned on the deployment of smart grid technology, including sophisticated algorithms that could track power consumption and ‘smart meters.’ These devices allowed utilities to manage energy drawn from a decentralized set of producers, among them private property owners with solar panels that could feed power back into the grid.
Those investments, in turn, paved the way for other conservation-oriented energy-policy shifts, such as time-of-use pricing, which provides ratepayers with a financial incentive to reduce consumption during peak periods and, in some jurisdictions, programs to encourage ‘fuel-switching’ for residential space heating, with electric air-source heat pumps replacing furnaces powered by natural gas or fuel oil.
The long-term vision for smart grids and distributed renewable energy is cities where individual homeowners and property managers can install a range of technologies – from rooftop solar panels to battery energy storage systems – that can provide low or no carbon energy to the local electrical grid, which traditionally distributes power supplied centrally, by large hydro, gas, or coal-fired generating plants.
Some electric vehicle (EV) companies are aiming to get involved in this market as well. Many firms are racing to develop so-called ‘vehicle-to-grid’ systems that would allow EV owners to plug in their vehicles and feed surplus energy from their cars’ batteries into the electrical grid in exchange for a fee or a rebate on their hydro bills.
The concept is built on the assumption that most private vehicles spend most of their time parked, in driveways or garages. When they’re stationary and not in use, the electrical charge stored in their batteries can be put to use in other ways, such as supplying additional power during peak periods, e.g., work hours, very hot days, or very cold days. In effect, the eventual deployment of vehicle-to-grid systems is akin to tapping into a massive storehouse of local, clean, and inexpensive power.
At those times when electricity is expensive, it could be possible for an office building owner to ‘buy’ electricity stored in the batteries of the EVS parked in the parking garage. If those batteries had been charged at night, when rates are low, the building owner can reduce its dependence on purchasing high-cost power from the local utility. Similarly, the building owner can power up a set of stationary batteries at night when rates are low, and then use the electricity during the day, when it is expensive.
Ultimately, smart grid proponents want to build cities where electricity is distributed not like cable television – in one direction, from a single provider – but rather like the internet, with power flowing in many different directions within an extended urban network. Households and businesses will not only consume electricity but also produce it via solar panels, stationary batteries, and EVS, all of which are set up to export power into the grid using specialized meters and other equipment.
As of 2022, this version of the future of electricity in smart cities remains unrealized, an aspiration with many moving parts. The EV market is growing quickly, but represents only a fraction of the overall vehicle sector. Governments and property managers are still figuring out how to deploy charging stations, while tech companies and EV component manufacturers are racing to build longer-lasting batteries.
Perhaps the most daunting impediment has to do with the management of this new distributed energy system and the complex demands that urban grids will face in the future. As EVS become more commonplace and building owners reduce their reliance on natural gas for space heating, the demand for electricity in big cities will soar, meaning utilities will have to bring in additional sources of generation, generated using low-carbon technologies like wind, hydro, or nuclear.
A portion of that new power will come from local distributed renewable sources: rooftop solar panels, stationary batteries, and EVS. For utilities, however, the task of managing both conventional and distributed sources of power is highly complex from a technical perspective and far less predictable than the conventional approach. Specialized electricity software companies have emerged with digital smart grid platforms designed to do this kind of load-balancing.
But even in forward-looking cities, the transition to distributed energy smart grids remains a work in progress. According to the International Energy Agency, utilities around the world are spending hundreds of billions of dollars upgrading aging electrical grids, but so far only a portion of that is going into smart grid ventures, although those investments are expect to grow in coming years as governments around the world race to meet net zero emission targets for 2050.
The sleepy, monopolistic world of local electrical utilities will be unrecognizable. The emergence of decentralized smart grids will eventually create new local energy markets that eclipse the publicly owned utilities, like Toronto Hydro, that have supplied electrons to urban ratepayers for well over a century.
Innovations in urban energy won’t just come from the world of electricity. Some cities, for example, are experimenting with mechanical energy transfer systems that collect and recycle waste heat in municipal sewer mains. In many parts of Europe and a growing number of North American cities, municipalities have invested in ‘anaerobic digestors,’ which siphon methane created by organic household waste. This so-called biogas is then purified and used for electricity generation (in place of conventional fossil fuels) or to power low-emission vehicles.
Climate-focused architects, meanwhile, have developed techniques for reducing energy consumption in buildings by up to 90 per cent. The so-called ‘Passive House’ school of design – which was invented in the early 1970s but popularized in northern Europe in the early 1990s – is grounded in a handful of core architectural principles: massive amounts of exterior wall insulation; construction methods that eliminate leaks and so-called ‘thermal bridges,’ which allow heat to escape; triple-glazed windows and heat-recovery devices attached to drains and exhaust vents; and orientations designed to optimize the use of the sun’s heat. Most of the components used in Passive House projects are not especially high-tech, but rather rely on basic physics – that if a building’s design prevents heat or cooling from escaping, it will require less energy.
Air quality monitoring, by contrast, has attracted considerable attention from smart city technology firms and researchers, largely because this kind of activity can be significantly expanded with the deployment of wireless air quality sensors. These include monitoring devices attached to lampposts and other urban infrastructure, an expanded network of air quality monitoring stations, and low-cost mobile sensors affixed to rental bikes and even pigeons. Other projects involve cross-referencing anonymized cellphone mobility data with air quality readings taken in various urban locations to assist in determining where exposure to ultra-fine pollutants was highest (Bousquet 2017).
Smart buildings, typically new office towers or commercial complexes, offer a much more involved application for wireless sensors. These buildings are fitted out with networks of thousands of IoT devices – temperature and motion detectors – that feed readings to automated control systems. These use artificial intelligence algorithms to continuously adjust HVAC equipment in order to optimize a building’s internal climate, thus reducing operating costs related to energy consumption. By contrast to the more speculative world of roving air quality sensors, the market for smart building tech is highly developed and competitive, and includes multinationals like Siemens or Schneider Electric that focus on giant property management firms.
As was true in a previous era with the emergence of scrubbers for smokestack industries, the adoption (and therefore efficacy) of new sustainability technologies – smart or otherwise – can’t be seen in isolation from broader political or policy developments, such as the introduction of strict air quality standards in response to mounting public alarm about pollution.
Indeed, regulation has been consistently shown to drive innovation. A case in point: California’s low-carbon fuel standard (LCFS) went into effect in 2011 and has since influenced similar policies in Oregon, Washington, and British Columbia. The standard provides incentives to transportation fuel companies to use low-carbon or renewable additives, such as biodiesel, or pay penalties. Since the LCFS came into effect, the carbon intensity of California transportation fuels – a measure of emissions per unit of fuel – has consistently dropped, while cumulative sales of hybrid electric or battery electric vehicles has soared, from 7,500 in 2011 to over 990,000 by 2021 (‘Zero Emission Vehicle and Infrastructure Statistics’ n.d.).
Another example of smart regulation is so-called ‘Energy Step Codes’ that set out targets for overall building energy performance – a critically important front in the fight against climate change.10 In 2017, both British Columbia and the City of Toronto adopted energy codes that establish minimum standards for new buildings, functioning like regulatory escalators that predictably become more demanding over time. Under the Toronto Green Standard, all new projects must meet the basic level, known as Tier 1, while more ambitious developments that satisfy the next-highest performance target (Tier 2) are eligible for financial incentives. The third tier applies to public sector buildings, while the fourth tier lays out the standards for net zero projects (i.e., that any carbon generated by the building is offset in some way – for example, with solar panels that feed green power into the grid). As the TGS is upgraded, the second tier will become the first tier, the third tier becomes the second tier, and so on. The goal, part of the city’s long-term carbon target, is for all new buildings to be net zero.
This type of progressive regulation produces benefits that extend beyond emissions reduction, and can be described as part of a smart city agenda. In Vancouver, for example, the Step Code has pushed building component suppliers to develop more energy-efficient products, such as triple-glazed windows – which are commonplace in Europe, where energy standards are high, but are still a premium product in North America. The Step Code has also spurred a development boom in so-called ‘tall timber’ construction – basically, buildings constructed from highly engineered wooden beams and pillars instead of carbon-intensive materials like concrete and steel.
The upshot is that these kinds of smart environmental regulations reduce carbon, create jobs and economic activity, and provide building owners with financial resilience in the form of reduced long-term operating costs.
Much more than Canada’s, the Netherlands’ climate policies reflect a great sense of urgency, given its exposure to sea level rise and flooding on rivers that flow into the country from the east. For that reason, both adaptation and mitigation have been central to the country’s plans for future-proofing its cities.
Rob Schmidt, a sustainability policy expert with the City of Rotterdam, points out that the Netherlands’ nine largest city regions collaborate to develop and test approaches and technologies: ‘We learn from each other how to cope with these so-called smart city projects.’ Each city has adopted a policy area: Rotterdam is focused on climate adaptation; Amsterdam, circular economy; Eindhoven, low-carbon mobility and energy transition; and so on.
The national government has launched an Urban Agenda that calls for negotiating ‘city deals,’ many of which involve smart city projects that typically include multiple partners, such as research institutions. ‘Our approach is focused on the opportunity and finding everyone you need to get to a solution,’ says Urban Agenda program manager Frank Reniers. ‘You put them in a room and try to innovate your way out of the problem.’
The Netherlands wasn’t always so collaborative. According to Frank Kresin, dean of the Faculty of Digital Media and Creative Industry at the Amsterdam University of Applied Sciences, Amsterdam in the late 2000s and early 2010s ‘was doing everything in its power to become “smart.”’ The city’s appetite for tech drove a great deal of private investment in automation and digitization.
But the infatuation with these corporate solutions, Kresin wrote in a 2016 study, ‘had some flaws,’ including the risk of excessive surveillance and an unquestioning embrace of the idea that the smart city was ‘a machine that needs to be optimized, with no consideration or understanding of the organic reality. It wants to maximize efficiency and avoid friction, so it simply and non-negotiably imposes topdown, non-transparent technological solutions.’
Kresin wasn’t the only one concerned about this drift. Beginning in the mid-2010s, citizen groups, entrepreneurs, and academic institutions pushed Dutch policy makers and companies to swap out the top-down approach in favour of a more grassroots philosophy that features extensive public engagement, citizen-science projects, and applied research.
‘The big threat is loss of autonomy,’ says Jan-Willem Wesselink of Future City Foundation, a Dutch network of municipal agencies, civil society organizations, universities, and technology companies seeking to promote a democratic approach to smart urbanism that aligns with a U.N. social development goal (#11) about resilient, sustainable, and inclusive cities. ‘Does Google or some other company decide how you use the city?’
Kresin describes one early effort at broadening the conversation. In 2014, Amsterdam Smart City, a tech incubator, distributed several hundred ‘smart citizen kits,’ which provided rudimentary sensors to allow people to perform environmental indicator tests on water and air quality around the city. Their findings were fed to the city. While the readings fell short of research-grade data, this experiment in citizen science attracted many participants, generated upbeat media coverage, and, in a few cases, led the city to clean up local beach areas. Its popularity also inspired Kresin and some colleagues to establish the Amsterdam Smart Citizens Lab, where civil society groups, academics, and government officials work together to find solutions to other urban problems.
The distribution of the kits ‘was a surprisingly successful project,’ says soil chemist Gerben Mol, a resilient cities researcher at Amsterdam’s Advanced Metropolitan Solutions Institute (AMS), a university– municipal government joint venture established to conduct more formal applied urban research.
In recent years, a growing number of Dutch city dwellers are finding venues to engage in local conversations or projects about putting urban data and technology to work in addressing the problems they see in their communities – in effect, a cultural, as opposed to corporate or bureaucratic, response.
All this grassroots work has had a bearing on AMS’S work. While some of its research falls under the heading of smart city tech – e.g., data visualization projects – other research initiatives are focused on parallel policy themes, such as the circular economy. One intriguing example: an AMS project that created a composite out of a glue-like bacterial residue and decontaminated wood fibre culled from septic waste (i.e., used toilet paper). Currently being tested is a potential application to use this composite as a binding agent in road asphalt.
Amsterdam Smart City’s community manager Nancy Zikken says the municipality has ‘embraced’ TADA.city, a network of European organizations that have pledged adherence to six core principles for digital city initiatives (inclusive, locally focused, controlled by residents, monitored, transparent, and broadly accessible).
She also says that Amsterdam Smart City screens applicants, such as start-ups, to ensure their proposals align with broader policy goals and have what Zikken calls ‘social value.’ As an example, she cites a firm that recently pitched a parking app that was rejected because it would likely encourage car use in a congested city whose residents want the opposite. ‘Most of the companies we’re working with really do see the value of incorporating citizens and using the wisdom of the crowd,’ she says.
In Rotterdam, city officials, who are driving the blue-green grid initiative, are also using public education, open houses, and other engagement tools to promote these projects, many of which will be installed on privately owned dwellings, using private capital, since the strategy is to attain sufficient scale to make an impact.
Rotterdam, interestingly, hasn’t created financial incentives. Rather, in discussions with private property owners, Paul van Roosmalen says his team stresses the benefits and explains the options for what’s possible – for example combining a rooftop reservoir with solar. ‘They can pick what they think would add to the quality of their specific land,’ he says. But there’s a more urgent appeal, too: ‘You can save your city from drowning.’
From the earliest days of the smart city tech boom to its apogee (circa 2018) and the hype around megaprojects like Sidewalk Labs’ plan for Quayside, sustainability has been positioned as one of the main benefits for cities thinking about investments in systems such as air quality sensors, electric vehicle charging infrastructure, smart temperature controls in apartments, district energy, and smart grids that draw on renewable power.
While these technologies – on their own, or even assembled into an extended development project – are enticing in that they hold out the promise of a greener form of city-building, some critics have pointed out the flaw in this approach: ‘“Smart city” technology is steeped in solutionism,’ argued Rebecca Williams, a Harvard Kennedy School fellow with the Belfer Center for Science and International Affairs, in a 2021 study on smart city trends. ‘[I]ts rhetoric and promotional materials are often couched with the promise of what it could solve rather than what it has demonstrably solved in similar instances.’
Other scholars have come to similar conclusions about the hyped benefits of these technologies. A 2019 study by a team of Norwegian and Swedish researchers concluded that energy sustainability smart city projects in three Scandinavian cities, which involved €70 million in funding from the European Union, had been oversold and were in fact older plans that were repackaged. (They included a new energy centre, administrative offices powered by renewable energy, home retrofits, solar panel installations, and smart building systems.) The authors pointed out that while the recipient municipalities foregrounded sustainability in their smart city proposals to the EU, the technologies they used weren’t particularly innovative, and the results, in terms of energy savings, proved to be ‘almost impossible’ to measure.
‘The way we understand and measure energy sustainability in a smart city needs reconsideration,’ the authors concluded, pointing out a long list of X-factors, including pre-existing budgets, plans, EU requirements, and the engagement of individual policy makers tasked with delivering on these undertakings. ‘By and large, these outcomes are highly contingent, and to a significant extent determined by the implementation of the smart city agenda by policy makers on the ground’ (Haarstad & Wathne 2019).
The broader conclusion is that clean/green smart city tech makes sense only when it is embedded in a wider policy and planning framework designed to promote more conventional urban or regional goals, such as intensification, transit investment, and grid decarbonization. EVS and a city fitted out with charging infrastructure won’t reduce emissions unless governments reduce the fossil fuels used to generate electricity. A homeowner who spends tens of thousands on state-of-the-art solar panels won’t dent their dwelling’s carbon emissions unless they first pump insulation into the attic and eliminate the drafts around doors and windows. And no amount of green technology investment can slow the emissions generated by sprawling, car-dependent cities built with vast quantities of concrete, asphalt, and steel.
What’s more, new solutions to urban environmental problems need not be high-tech (i.e., technology if necessary, but not necessarily technology). In China in recent years, for example, municipal authorities in sixteen metropolitan regions with water-scarcity issues have pursued so-called ‘sponge city’ strategies – using native species plantings, wetland construction, permeable surfaces, and rainwater harvesting to reduce runoff and improve water absorption. As one former Chinese official told the Guardian, ‘A sponge city follows the philosophy of innovation: that a city can solve water problems instead of creating them’ (Harris 2015).
Viewed in these ways, the Dutch approach to smart cities and sustainability is, well, smart, with support for tech innovations like blue-green roofs, but as just one element of a national policy framework that promotes urban sustainability through regulation, infrastructure investment, R&D circular economy initiatives, and public awareness.
10. Building-related emissions account for about half of all carbon released into the atmosphere, and the International Energy Agency reported that building-related CO2 reached an all-time high in 2019.