Perhaps the biggest single step that cities can take toward a sustainable future is to create economies that greatly reduce materials use, (re)circulate most materials, and rely largely on renewable energy. The challenge is different in wealthy countries—which largely have materials-intensive infrastructure in place—than it is in poorer nations that need additional schools, hospitals, and transportation networks. Scientists have suggested that the needed increase in resource productivity could be huge in wealthy countries—on the order of 80 percent. Developing countries can focus on designing their additional future infrastructure to be as efficient as possible. This challenge is mammoth and will require all the ingenuity and moral strength that citizens and their leaders can muster.1

Reduced Urban Material Footprint

City leaders will need to seek absolute reductions in virgin material and fossil energy use, not just efficiency gains that merely slow the rate of increase in consumption. In recent decades, global resource use has grown 1–2 percent more slowly each year than economic growth, largely in developed-country cities where most infrastructure is already built. But this decoupling has not ended growth in resource use in developed countries, nor does it open up the “ecological space” needed to allow poorer cities to grow. Efficiency gains will be only one part of a much broader materials reduction strategy in cities.2

Efficiency gains will be only one part of a much broader materials reduction strategy in cities.

That comprehensive strategy will need to include the creation of “circular economies” that increase substantially the rates of recycling and reuse of metals, plastic, and other materials. In a circular economy, products are designed for durability, disassembly, and refurbishment. Recycling is greatly enhanced. Production is designed to minimize waste, through co-location of factories that can feed off of each others’ wastes. (See Chapters 12 and 13.) Stated conceptually, sustainable cities “close nutrient loops,” whether those nutrients are technical (the metal and mineral inputs to factories) or biological (the food and yard wastes that are composted for plant growth) in character. Such cities also increase energy recovery.3

To meet the goal of an 80 percent increase in resource productivity, much more is needed than higher rates of post-consumption measures such as recycling. Clever strategies, many centered around providing people with services rather than goods, can accelerate reductions in materials use. A good example is car sharing, which offers people private transportation without multiple private cars per family, reducing a person’s materials footprint. Tool libraries, such as the one in Berkeley, California, which is a branch of the city’s library system, are another example. City residents can choose from hundreds of tools, from power drills to ladders to carpet cutters, providing a less-expensive, and materials saving, alternative to tool ownership. Sustainable cities will feature many more service providers and repairers than are found in cities today.4

Cities on the path to sustainability can establish a rational hierarchy of effort for materials reductions. A product study by the Joint Research Centre of the European Commission found that food and drink, transport, and housing were consistently the consumer items with the greatest environmental impact. These economic areas, taken together, accounted for 70–80 percent of the lifecycle impact of the products studied, suggesting that these areas might be prioritized to achieve materials reductions.5

Cities also can jumpstart the market for green products by instituting a green procurement policy that reduces waste, conserves natural resources, eliminates the use of toxic materials or pollutants, and promotes the use of recycled content. The policy can apply to virtually all city purchases, from paper and cleaning products to cars. In Santa Monica, California, green purchasing priorities have resulted in a municipal vehicle fleet consisting of more than 80 percent alternative-fuel and advanced reduced-emission technologies. The European Union, meanwhile, has set standards for 18 products for green procurement, as an assist to meeting its goal of 50 percent green-product purchases.6

Although efficiency alone is insufficient for creating sustainable cities, it is still critical, and opportunities abound.

Although efficiency alone is insufficient for creating sustainable cities, it is still critical, and opportunities abound. The experience of Los Angeles, California, is instructive. In 2013, the city completed a huge street lighting retrofit, installing 140,000 bright but efficient LED (light-emitting diode) fixtures across the city. The $57 million program has yielded energy savings of 63 percent (equivalent to removing 9,500 cars from Los Angeles streets) and a reduction of 47,000 tons of carbon emissions. Crime in the better-lighted streets is down by 10.5 percent. And program financing was manageable: loans are paid back over just seven years, using energy and maintenance savings. Once the city’s loans are paid off, it expects to realize $10 million per year in savings.7

Finally, large reductions in materials and energy use may require changes in consumption, including more emphasis on public rather than private consumption. Attention to placemaking (see Creative Placemaking) can help create venues for “environmentally light” consumption. People who enjoy an evening stroll to a public plaza are consuming city assets—streets, streetlights, and public space—in a way that involves a minimum of materials and energy. Thus, in a sustainable city, people may spend much more time at concerts, sporting events, and festivals, and much less time at shopping malls.

Reduced Urban Energy Footprint

Cities also will need to shrink their energy footprints by creating more energy-efficient infrastructure and converting their energy supplies to renewable sources. Cities can target the largest users of energy, especially buildings and transport, for efficiency upgrades. Setting a passive house standard for new buildings and renovations—a globally recognized benchmark of building energy efficiency—can dramatically reduce energy use. (See Chapter 9.) Carbon-free transport can be prioritized, with heavy emphasis on biking and walking, then on public transport. (See Chapter 11.) In addition, cities can promote district heating (and cooling), and combined heat and power to capture wasted energy. Efficient appliances can be promoted through regulation, standard setting, and green procurement policies.8

Greater efficiency facilitates the transition to renewable sources of energy, which some cities now see as the eventual source of 100 percent of energy use. (See Chapter 16.) Many sources of renewable energy are found in cities themselves, including power from solar photovoltaics (PV), small-scale wind power, heat pumps and geothermal systems, biomass, and methane capture from sewage. Cities also can connect to regional and national renewable energy grids.9

See references for this text.

〉〉 Next: A Prominent Place for Nature


Gary Gardner

Gary Gardner is director of publications at the Worldwatch Institute and co-director and contributing author of the State of the World project.

Read more in State of the World: Can a City Be Sustainable?