BBC Future

Living buildings for tomorrow’s cities

About the author

Rachel Armstrong is a sustainability expert who creates new materials with some of the properties of living systems. She is a TED speaker and also a senior lecturer at the School of Architecture, Design and Construction at the University of Greenwich in London.

  • Greening the city
    Cities rely on pollution-creating technology – and there is significant pressure to limit their effect on the planet as urban populations soar. (Copyright: Getty images)
  • Nature's design
    Sir Norman Foster’s iconic "Gherkin" in London takes its structural cues from a deep sea sponge through the building's use of a hexagonal "skin". (Copyright: Getty Images)
  • Sunken treasure
    The Gherkin’s lattice was based on the Venus Flower Basket Sponge, which has a skeletal structure with a strength 100 times that of aluminium. (Copyright: Science Photo Library)
  • Turning over an old leaf
    Needle leaf evergreens – like silver birch – have many small, thin leaves which make the most of the scant sunlight in their habitats. (Copyright: Science Photo Library)
  • Desert living
    Magnus Larsson's Dune projects uses the building abilities of bacteria to create a natural concrete which could be used in arid desert conditions. (Copyright: Magnus Larsson)
  • Shellfish filtering
    So-called "oystertecture" – in which shellfish are grown on metal gates and used to filter water – could be used to treat polluted water. (Copyright: Scape/Landscape Architecture)
  • Self-repairing material
    Biological concrete is a type of cement which has implants of a special bacteria which form solid plugs when they come into contact with water. (Copyright: Henk Jonkers)
  • Concrete improvements
    The cement has already been used by researchers to create physical buildings, where its self-repairing properties can be tested in real-life conditions. (Copyright: Henk Jonkers)
Cities rely on systems that pollute our world. In the first expert viewpoint in the Building Tomorrow series, sustainability expert Rachel Armstrong looks at how nature is providing the inspiration for greener, more responsive designs.

It is morning, in a city of the future. Wafer-thin artificial leaves separate with the rising sun as buildings wake up. They continue to follow the sunlight over the course of the day, sucking dew and carbon dioxide out of the air. These substances are filtered into the fleshy fabric within the walls of our homes, not dead spaces but active processors, like stomachs packed with thriving microbial colonies. They generate heat, recycle grey water and filter effluents to produce rich, native soil that has a commercial value and is used to grow plants in green plots, or window boxes. We are now producers, not consumers.

There are no more infertile stretches of asphalt sprawled over our urban rooftops but an expanse of vegetation which processes the city’s rich chemical landscapes – and it is no longer possible to tell which of these vibrant structures are artificial, or natural.

Visionary ideas about our near-future cities are helping develop new approaches in human development without necessarily being constrained by the limits of what is currently possible.

Modern cities are run and populated by machines to such an extent that we no longer really notice them. And while machines are useful, they consume fossil fuels and transform them into energy, carbon dioxide and industrial pollutants – which, on an industrial scale, produces a world which Rachel Carson, author of the seminal environmental book Silent Spring, noted is "not quite fatal". In recent years we’ve looked to renewables to avoid the need for using fossil fuels – but the percentage of our energy provided by these alternatives remains small compared with our overall consumption.

Yet, there is an alternative technology available to us, which we have barely begun to apply to its full potential. Nature provides a rich portfolio of sometimes unlikely living technologies that may shape our near-future lifestyles in new ways. The practice of biomimicry already taps into nature’s ingenuity – for example, the famous hexagonal skin of Norman Foster’s "Gherkin" was inspired by the Venus Flower Basket sponge, which has a lattice exoskeleton.

These solutions are currently realised through industrial processes. But we have reached a point at the start of the 21st Century where we do not have to copy nature but can directly design and engineer her processes with such precision – and on a range of scales – that we can think of them as a new kind of technology.

Living technologies have unique properties that may enable us to imagine and realise our urban spaces in new ways, since they are adaptable, robust and have an incredible ability to transform one thing into another. Think of how trees share common technologies (leaves, trunk, roots) adapted to different kinds of environments and using a range of resources. For example, needle-leaved Canadian evergreens make the most of scant sunlight and their leaf litter feeds the acidic soils that nurture networks of microorganisms, such as nitrogen-fixing bacteria, which in turn, enriches the food for the trees.

In the near future, we will begin to tap into the technological potential of this "metabolic" diversity and strategically use it within the fabric of our cities.

While trees are complex organic structures that require substantial infrastructures and resources to nurture them, biotechnology has revealed that multicellular organisms can perform similar processes – but even more powerfully. Although these creatures cannot be seen with the naked eye, they are much easier to keep and much more vigorous than trees.

Indeed, architects are already proposing that micro-organisms may power our cities. For example, Alberto Estevez’s Genetic Barcelona proposes using synthetic biology techniques - which enables us to grow organisms that do not exist in nature by manipulating their DNA – to create trees that produce a natural light-producing protein usually found in jellyfish. So, not only would we be able to enjoy the mood-elevating wavelengths of the light emitted by these plants, but we would also benefit from not having to rely on fossil fuels and central power grids to provide street lighting.

In the near future our buildings may also be "grown" by industrial-strength microorganisms. Some of these may form the basis of self-healing materials such as, Henk Jonkers’ biocrete, where bacteria are mixed into traditional cement and form solid plugs when activated by water that seeps in from fine cracks in the material. Other projects, such as Magnus Larsson’s Dune, are more ambitious. Larsson’s plan involves harnessing the metabolic powers of a sand-particle-fixing species of bacteria to produce sandstone or marble in deserts thought to be too hostile to live in.

Within modern cities, the value of harnessing the transformational powers of communities of microorganisms, called bioprocessing, is being realised in wastewater gardens. These may be thought of as bacterial cities within our own, which are fed with and transform our waste organic matter into useful substances. Rather than being noxious sumps of filth and disease, these sewage plants are popular visitor attractions, odourless greenhouses with the look and feel of a botanical garden (such as Koh Phi Phi Don in Thailand). Bioprocessing units may be designed to house different kinds of ecologies to suit particular habitats. For example, in estuary environments so-called "oystertecture", in which shellfish are farmed on sculptural metal structures, could be used to filter impurities, improve water quality and increase biodiversity.  

These developments in living technology suggest that we will evolve solutions using the transformational properties of natural systems. Living technologies build upon traditional skills that work in combination with new scientific knowledge. Importantly, since biology is everywhere, these approaches are not confined to Western societies. Increasingly DIY bio communities are learning how to "hack" natural systems and diversify living technology applications. This may streamline global human development with such natural processes so that our lifestyles are more sustainable, less environmentally disruptive and lead to cities which are better places to live.

Perhaps the future of our urban environments will not be about designing buildings, as we know them, but in the production of synthetic ecosystems, which improve the quality of our lives.

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