ABSTRACT
Are eco-cities a practical possibility or just utopian fantasy? New buildings can be zeroenergy, but old ones aren’t. Wholesale replacement is unaffordable. So can cities function in a sustainable way? Or, re-phrased: as they consume two-thirds of all global energy,1 they must. So how can they? Sustainability is about ecology. But although life depends on this, sustainability isn’t only about ecology. I used to think it was, so was disappointed every time eco-features were axed. Economic success didn’t depend on them, so their expense couldn’t be justified. Feeling betrayed, I didn’t realize the fault was mine. But a decade of working on a mixed-use urban development taught me how economic, social and ecological sustainability depend upon each other. They’re as irrevocably linked as is short-term profit to high economic-risk and social and environmental exploitation. Need doesn’t drive change. Money does. Without economic sustainability, ecological sustainability doesn’t happen. Without social sustainability, things don’t function, so they’re neither ecologically sustainable nor profitable. For this reason, I now listen closely even to racist community groups. These tend to disguise bigotry as ‘reasonable’ grievances (like Friday parking overload outside mosques): concerns I can deal with. I also always listen to anti-sustainable developers (but would never work for them either). What they see as profit-drivers, I see as social and environmental forces to harness for other ends. Nowadays, even from a strictly commercial perspective: ‘Sustainable retail projects are profitable, in good measure, because they are pleasant environments that tenants and shoppers prefer.’2 Although economically, socially and ecologically motivated projects have different agendas, unless these are symbiotically aligned, none will be sustainable. Single-issue aims produce more problems than they solve. Only multi-objective approaches don’t. Traditionally, cities had to be economically, socially and ecologically sustainable to survive. Economically unsustainable ones couldn’t afford garrisoned defences. Socially unsustainable ones had revolutions. Ecologically, they were unavoidably enmeshed in local cycles and limited by local carrying-capacity. Meat can walk hundreds of miles,3 but vegetables too long in an ox-cart aren’t fresh. This and disease limited city size. Modern cities are different. Compactness may reduce heating and travel needs, but dependency on imports and exports increases transport demands. Moreover, once cities outgrew their
local support-base, their relationship to their ‘host’ eco-systems became parasitic not symbiotic: taking not exchanging. This makes ecological systems linear, not cyclic: locally open, only closed globally. Global systems distance action from consequences, so don’t trigger self-correcting feedback. Does this mean sustainable cities are impossible? Challenging, certainly, but I’ve never quite been convinced of the meaning of ‘impossible’. It’s definitely not hard to go a long way towards this ideal. The technologies already exist and, increasingly, the consciousness and even (some) political will. Sustainability involves many issues, but renewable energy and cycles of matter are fundamental. For both, the first step must be localization. Unless feedback consequences are visible, good intentions can’t guarantee good results. In nature, small cycles link into bigger ones, but locally, they’re substantially whole. Multi-path links maximize flexibility and resilience. It’s similar with cities. They can’t wholly feed, water or fuel themselves, nor dispose of their wastes. For this, they’re bound to their region. But, like
nature, many cycles can be substantially complete at a local scale: in city, district, neighbourhood or building. Although some eco-buildings suffer from ‘the bigger the name, the grander the claim’ syndrome, energy conservation centres on individual buildings. Generation, however, is multi-source. With building-mounted photovoltaic panels, in-river and on-weir hydro-generators, wind-power (not building-mounted!)4 and waste-fuelled CHP,5 cities could cover most of their electrical needs. Although weather-powered systems’ output is related to weather not demand, system diversity balances this out. Wherever energy is needed as motive power or heat, lower-technology systems (e.g. wind-pumps) obviate power-to-electricity and electricity-to-mechanical-power losses: more efficient, less to go wrong and easier to see cause and effect linkages. Heating usually involves a mix of individual-building contributions, like solar water-and space-heating, and city-wide systems, like district heating and bio-gas
from organic waste. Many industries produce waste heat. So does refrigeration: ice-rinks, supermarket cabinets, air-conditioners. All this is re-usable. This brings up issues of heat matching. Building heating demand is seasonal but timber drying, swimming pools and low-temperature industrial processes aren’t. Heat-matching needs proximity, making it both a design and technical issue. Of all cycles, probably the most obvious is water. All life depends on water. But how many people know where it comes from and goes to beyond the limits of tap and plughole? Rainwater is normally piped away, increasing flood risk. But it’s good enough for non-potable uses – namely, most of the water we use. For irrigation, paving run-off will do;6 but for indoor use (e.g. laundry, toilet-flushing), it must be roof-water. Rainwater isn’t fresh if stored too long, so tanks should be small enough to be frequently flushed by new rain. Hard surfaces multiply run-off volume. Re-graded ground levels can direct it, and tanks’ overflows, to trees; then, via sand-filters, to ponds and cisterns for (wind or photovoltaic) pump-fed streamlets. These clean and cool air, and invigorate and delight us with their song and ripple-reflected sparkle. One waste we all produce every day, but don’t like visible, is sewage. Domestic sewage mixes faeces, urine and greywater. Urine is nutrient-rich and, using separating toilets, can be collected for agriculture.7 Even mixed, sewage can be treated aerobically in Living Machines (sequential containers in tropical-climate greenhouses), reed-beds, wetlands, lagoons, and even artistic water-gardens in parks, or (at larger scale) anaerobically to produce bio-gas. Separating toilets enables unpolluted urine to be collected
for fertilizer (as done in Sweden since the 1980s).8 Greywater is easy to treat till clean enough for irrigation and toilet-flushing. Being low pollution, treatment opportunities range from reed-beds separating roads from cycleways to cascade-linked planter troughs on walls. Sewage-treatment may require estate-sized systems, but greywater use and urine separation are building-scale matters. Rubbish dumps are odiferous, unsightly and expensive. Most inorganic waste can be recycled. Dumped, organic refuse putrifies. Needlessly! It’s easily composted: municipally, or by householders in gardens or worm-bins. This doesn’t just close the food cycle but, through the act of separating compostable from non-compostable material, raises consciousness. Unless they’re just overblown suburbs, cities can never grow all their own food. Nonetheless, Havana grows 90 per cent.9 Even in cooler climates, they can grow a surprising lot. Some 40 per cent of Russian food comes from small private plots fringing cities. Britain survived wartime blockades by growing food on every available bit of land – including within cities. Rooftop gardening, green terraces and window greenhouses bring (at least some) food-growing within almost universal reach. In dense cities, land cost and space scarcity encourage converting rooftops into gardens. So popular are allotments, there aren’t enough.10 In countries like Russia, Germany and Sweden, these double as places of sensory delight where families live all summer. Urban horticulture, however, isn’t problem-free. Vandalism, crop-robbery, even waste-dumping, are common. Community-surveillanced locations minimize such abuses. Public-realm edible-landscaping is also possible. Todmorden, England, has this all over the town: free food and striking community-formative benefits.11
