Terraforming the new economy

Australian cities can be “terraformed” so that they become part of a climate-change response, rather then being a cause of it.

Terraforming is "Earth-shaping" of a planet, moon, or other body. It is the hypothetical process of deliberately modifying atmosphere, temperature, or ecology to resemble those of Earth in order to make it habitable by humans.

In this context the term describes the transformation of a city’s built environment by sowing its wasted space - its roofs and walls - with growing plants, so that it more closely resembles a rural countryside in terms of environmental advantages. Terraforming is a convenient term for a most convenient truth.

Terraforming is not entirely new. The practice of “sod roofing”, using slabs of growing turf to build a roof for one’s house, has been going on in Europe for thousands of years. What is new is the dramatic upsurge in interest in developing it to suit the urban landscape of the 21st century and in the sophistication of the techniques now being used.

North America and Europe now have 15 green roof infrastructure national associations. They consist of urban planners, built-environment educators, engineers, architects, horticulturalists, developers, specialist builders and municipal government.

Their international organisation is the World Green Roof Infrastructure Network (WGRIN), which next meets early in May, 2007 in Minneapolis, United States, to launch a worldwide campaign that aims to lead a global trend to terraform much of the world’s built environment.

Terraforming is demonstrably good for the economy. Australian built-environment professionals can team with Australian primary producers for new business opportunities. Both can specialise in the nascent urban greenery market.

Australia has formed a member organisation of WGRIN - Green Roofs for Healthy Australian Cities. WGRIN plans to include many Asian, African and South American countries in its work - notably China and India. This has significance for our credibility as a player in the new terraforming world economy that is emerging as a response to climate change.

Green roofs and walls of terraforming can be retrofitted or designed in new construction. Design varies according to roof load and slope, solar aspect and budget. Two types of green roofs are favoured - extensive (low profile) and intensive (high profile). A combination of both is also possible.

Australia made a serious start in green roof development with the construction of the new Parliament House in Canberra in the 1980s. Its three hectares of lawns on a concrete structure should have triggered much more interest among urban designers than they in fact did.

Quarter of a century elapsed before Australia began serious green roof development. In February 2007 a group met to develop guidelines and regulations for green roof and green wall structures. These have four important criteria:

1. buildings for green roof and wall terraforming must be made water-tight, with no root penetration;
2. appropriate species of hardy plants must be chosen and established on well-designed substrates;
3. each green roof and green wall plan must have a sound integration of professional expertise in both water-proofing and horticulture - plant selection, substrate choice, plant establishment and plant maintenance; and
4. each building approval for green roofs and walls must have a long-term maintenance plan for both the waterproofing and the greenery.