Cities Alive is the new branding for construction firm Arup's integrated idea of sustainable cities that incorporate nature as green infrastructure, which they have launched in a new report and book: Cities Alive: Rethinking Green Infrastructure.

Written as a combination of vision statement and manifesto by the Foresight + Research + Innovation teams at Arup, it is supported by the Landscape Institute and the Royal Botanical Gardens in Kew, west London.

It shows how the creation of a linked city ecosystem and the incorporation of green infrastructure with imaginative design can help to create healthier, safer and more prosperous cities. It represents a call for green infrastructure to have a much more influential role in the planning and design of cities and urban environments.

Green infrastructure means anything from open spaces, natural areas, woodland and parks; green streets, squares and public realm; sustainable drainage systems and healthy waterways, cycle ways and pedestrian routes within city environments; and smaller-scale green roofs, walls and facades.

"The professions must fundamentally rethink 'green', not as an optional add-on, a desirable enhancement or a dutiful nod towards biodiversity, but as a fundamental part of the solution," says Sue Illman, President of the Landscape Institute. "We look to technology to solve our problems, but now we must equally understand the power that nature can contribute to urban technology and science."

The document calls for five key requirements which characterise living, or regenerative, cities:

1. the recognition that greening cities is more than an aesthetic consideration but a fundamental part of an urban ecosystem that improves social interaction, and physical and mental health;
2. landscapes must be made to perform multiple tasks from spaces for social interaction to climate change resilience;
3. much more imagination amongst designers and planners in both envisaging city-wide strategic projects and reimagining uses of existing small spaces;
4. the wider use of advances in technology to measure the value that nature gives us through ecosystem services;
5. an integrated approach to delivery that breaks down barriers between departments to connect policy and achieve long-term benefits.

"The role of green infrastructure in addressing the challenges of the 21st century cannot be underestimated," said a position paper published by the Landscape Institute last year called Green Infrastructure. "It is a natural, service-providing infrastructure that is often more cost effective, more resilient and more capable of meeting social, environmental and economic objectives than 'grey' infrastructure."

Merrick Thompson, a senior member of the Institute, writing in that publication, added: "People want to be reconnected with nature and they want to transform underused land to produce clean air and clean water, good microclimates and good food."

An illustration of what such a city might look like in the future presents 25 separately identified features:

A selection of ecosystem service benefits of urban green infrastructure

Transport developments

• Bike sharing and cycle lanes
• Automated public transport
• Underground roads
• Automated private cars

Green infrastructure

• Vertical farming
• Green roofs, walls and facades
• Cool city parks
• Extensive green networks
• Green bridges
• Carbon sinks such as trees
• Green corridors for wildlife
• Underground parklands
• Glowing trees utilising bioluminescence

Public space adaptation

• Urban wetlands
• Public realms, streets and squares
• Adaptable public spaces
• Entertainment in public spaces
• Interactive spaces
• Augmented reality with smart technology
• Smart weather covering
• Healthy streets
• Glowing pavements
• Permeable paving
• Sustainable urban drainage systems
• Rainwater capture
• Solar panels

Environmental and economic benefits include more effective and lower-cost storm water management since pavements are built of permeable materials (as in Chicago now), and green roofs or water storage bunds or swathes are provided.

Other economic benefits come from energy and resource efficiency; examples are given of how much a combination of trees, sustainable drainage, green walls and roofs, and food growing can contribute. Also significant is the potential boost to the local economy – as in New Road, Brighton where local businesses benefited from increased walking and cycling, and a reduction in motor vehicle use meant improved health and air pollution.

The document summarises further benefits of green infrastructure and the tools that help achieve it, including details of the Biotope Area Factor used in Berlin, which requires a certain proportion of the development area to be left as a green space.

The iTree system, a tool for assessing the ecosystem value of trees, is discussed to show the monetary value of trees for energy savings, atmospheric CO2 reduction, improved air quality, storm water runoff, and amenity and aesthetic considerations.

600,000 street trees provide an annual benefit of $122 million, more than five times the cost of maintaining them, according to an iTree evaluation of trees in New York's five boroughs.

Recommendations for achieving Cities Alive through delivering green infrastructure-led design is followed by a section on strategies for designers. Appendix 1 has a checklist for landscape architects and city designers and Appendix 2 gives selected facts and figures on green infrastructure.

The document is littered with many existing examples of the above initiatives in various cities:

Madrid Río Project

The city of Madrid dug 43 kilometres of tunnels into which the exit routes and a 6km section of the M-30 ring road motorway disappeared. West 8, working together with MRIO arquitectos, a joint venture of three Madrid based firms led by Ginés Garrido Colomero, designed the master plan for the reclaimed riverbanks and the new urban area. The Salón de Pinos, is a key part of this, designed as a linear green space, to link the existing and newly designed urban spaces with each other along the Manzanares River, located almost entirely on top of the motorway tunnel, with a "choreography" of 8,000 pine trees planted with a repertoire of cuts. This new green urban space has become an integral part of the city, offering a rich and healthy parkland filled with a wide range of sports, leisure and cultural facilities.

Hammarby Sjöstad:

Stockholm's largest urban construction project. The "Hammarby model" has become an example for environmentally friendly city development around the world. When completed in 2017, 26,000 people will be living here in 11,500 apartments. The district has been planned using an eco-cycle approach and is intended to showcase ecological and environmentally sensitive construction and living.

Queen Elizabeth Olympic Park in London

This set new standards by weaving biodiversity and nature into the core of the project utilising a green infrastructure-led design approach.

The High Line New York

This project captured the public's imagination and helped redefine and globally influence what urban green space can be; it demonstrates how quality city space can positively utilise obsolete city infrastructure and also how a project of this scale can be successfuly managed by the local community.

Perhaps the last word should be left to Peter Head, who is quoted in the report from his book: 'A New Approach to Resources' (2013):

"Our current mind-set is that economic success requires increasing consumption — instead we should be valuing processes that reduce consumption — instead of focusing on GDP growth, we should place more value on improving health, education and quality of life."