UK Green Forum's Mark Long outlines the principles and reports on greening in China.
The Green City Guidelines - Techniques for a Healthy Liveable City arises from consultation with around 60 different researchers and international experts in the field of green infrastructure and liveability.
Launched at the Global Green City Summit Forum in September, it has been created to demonstrate through case studies and summaries of scientific reports what can be achieved through the application of green city principles and the green city philosophy itself and draws on examples taken from three continents.
The result is a resource for use by landscape professionals, planners, developers and budget-holders. It puts ammunition into their hands to win arguments and get green space the position it deserves.
Lead author Michelle de Roo is a landscape and urban designer with Niek Roozen Landscape Architects. She explains: "Certain basic principles apply universally, but what this book sets out to do is to inspire practitioners everywhere to find the solutions that work in their own contexts. It is not a rigid or prescriptive guide, but rather a source book of examples and worked approaches that can lend weight to the case for green infrastructure everywhere."
The project was made possible with investment from the Dutch government, International Association of Horticultural Producers AIPH and Plant Publicity Holland.
How do the guidelines function?
The structure of the book is based on four sections - green cities, green neighbourhoods, green streets and green buildings.
Green cities deals with key elements of the planning process and its relationship with green space. At its heart is the concept of "invest together", that planning from the beginning to build in the green infrastructure element delivers maximum benefit in energy savings, health, property value, biodiversity and image.
Having established the value of the approach, evidence-based information is put forward on aspects such as the filtering and air-quality improvement that are possible with specific species.
One of the first guideline concepts is using trees and plants to reduce background concentrations of air pollution. All plants contribute to the improvement of air quality but some species are more effective than others.
"Within walking distance" is given a dedicated chapter, with the guideline to "develop ample and usable green spaces within walking distance of all residents".
This is supported with health data from a number of different sources - for example, the UK Foresight Report and Vitamine G, a Dutch study of the actual health indicators among residents living in areas with various proportions of green to grey.
Green neighbourhoods examines the role that green spaces serve as part of the wider neighbourhood and the contribution they make to social and catchment-scale functioning of the community. It identifies the benefits of parks and urban green space in counteracting the heat island effect.
The guideline encourages the prevention of city-wide hot spots by spreading parks and green around the city and increasing the overall tree canopy area. Research data from the Alterra Institute at Wageningen University in the Netherlands contributes to the evidence-base for this.
The importance of including residents at the consultation stage, creating respect for public green space, planning of activities and the transformation of unused green space within the city are all included to support the overall guideline.
In this case, direct testimony is provided by Trees for Cities chief executive Sharon Johnson. She cites sociological studies carried out with Nottingham Trent University that gave a clear indication that: "A healthy, safe city is one in which residents get out onto the streets and into green spaces. By getting involved in decisions, residents feel ownership of these spaces."
Grow your own promotion
The potential of urban farming, with supporting examples from Detroit and Havana, to enhance the "resilience" of cities is drawn in under the guideline. It promotes opportunities for urban residents to grow their own food within the city limits or even within their own neighbourhood.
Green Streets examines how street trees and plants contribute to the effective functioning of streets in relation to air quality and the urban microclimate. The first guideline relates to liveability: "Prevent local hot spots in urban plazas by planting trees to increase shade, reduce wind and make outdoor spaces more comfortable."
This is grounded in scientifically-derived knowledge in relation to how air moves through open spaces and trees within them. Air circulation, using trees to control wind speeds and getting the layout right to achieve positive outcomes are key. The right design helps to prevent the "green tunnel" effect, where pollution actually gets trapped at street level. Benefits of incorporating pre-existing trees into a planting scheme are examined and the benefits of big specimens are also discussed.
The liveability factor
Green buildings explores how the performance of buildings can be enhanced through green roofs and walls, interior landscaping and positioning in relation to existing landscape features.
The first guideline points to how the intelli- gent placing of trees and green structures can contribute to liveability: "Improve the microclimate around and in buildings by placing trees and green structures strategically outside buildings." This extends to placing buildings within the existing landscape in such a way that it enhances their performance, as well as equipping buildings with green roofs and walls where space is limited.
The benefits of greening buildings in a physical sense are now well understood by researchers, but information on how to achieve the best outcomes may not always be so accessible. The book provides a breakdown of green wall types and where they function best to encourage readers to dig deeper into the applicable solution for their situation.
Interior landscaping is not neglected. The final guideline suggests: "Create a more comfortable climate indoors with the use of indoor plants. This has a positive effect on the psychological and physical well-being of the building users." The landmark case study quoted is the Vancouver Convention Centre, which has a 24,281sq m green roof.
To obtain a copy of the guidelines, email mlongoptima@btinternet.com.
The Green City in China
Environmental crisis precipitated China's action on urban greening. Speaking at the Global Green City Summit Forum in Xi'an, Professor Peng Zhenhua, chief scientist of the Chinese Academy of Forest Science, outlined how following 15 years of hyper-industrialisation, air, water and soils were heavily polluted in most industrial areas and the heat island was causing severe problems in the summer months.
In 2002, an expert panel including 300 forestry professionals carried out a nationwide study. The result was a strategy for the sustainable urban forest.
This included developing the nursery industry to provide the stock needed and the development of a strategy to change the urban environment.
Professor Xiaoming Liu from Beijing Forestry University school of landscape architecture outlined three important structures that influence the extent to which green infrastructure is now present in Chinese cities.
"We have a national and provincial level one Garden City and level two Eco-Garden City initiative, launched by the Ministry of Housing & Urban-rural Development in 1992. It is led and supported by central and regional governments and funded by city governments. So far, among 657 cities and 2,856 counties across the country, 219 cities and counties have met the criteria."
According to Liu, Beijing, Shanghai, Xi'an and Suzhou all meet the standards, which are periodically reassessed. There is a national Urban Greening Act on the statute books and a legal requirement for cities to deliver varied green space, he explains. Meanwhile, there is now a growing appreciation across the country that green space increases the desirability and value of residential and commercial property.
Online updates
Supporting the guidelines, the Green City website www.thegreencity.com has been created to broadcast new information that becomes available from scientific studies and new examples. It is a vital mechanism for augmenting and updating the data contained within the first edition of the guidelines book.
Spreading the message
The International Association of Horticultural Producers AIPH was set up in 1948 to support businesses trading internationally in all categories of horticulture.
President Doeke Faber explains: "To ensure health and well-being in high-density urban areas, we promote the use of green spaces, the availability of playgrounds for children and parks for the elderly to relax and exercise. We promote the use of plants in offices and hospitals because it has been proven to positively influence recuperation time. Promoting the messages of the Green City has become a significant part of our work."
