Diagramas de clases

KEY POINT: The concept of ESD requires an engineer to consider and take account of the broader environmental, social and economic consequences of their work.

Economic, social and environmental analysis of engineering options or outcomes form what is called the triple bottom line (TBL). For engineers, the TBL can be viewed as a set of design criteria which can be folded into the engineering method, sitting alongside technical measures, to inform sustainable design choices. In chapter 2, you developed criteria to judge between the different makes of car a client could afford to buy, and explained the pros and cons of the different car options in terms of these criteria. The process of negotiating criteria with a client and explaining options in terms of these criteria is vital for producing outcomes that satisfy the client’s needs. In straightforward problems such as choosing a car, optimising batch chemical conversions, or improving safety conditions on a building site, the criteria for a ‘good’

solution are relatively easy to agree upon.

triple bottom line (TBL) A set of design criteria that can be folded into the engineering method, sitting alongside technical measures, to inform sustainable design choices.

But what happens when a client is not the only one in need of a result? What happens when engineering decisions have to be made and judged using criteria imposed by society? What

happens when a pro or con is uncertain, difficult or even impossible to judge? What happens when a problem you are engineering a solution for is complex and urgently needs to be resolved?

In these situations, sustainable engineering comes into play. Sustainable engineering has emerged from the general concept of ecologically sustainable development (ESD), and it allows engineers to tackle ‘wicked problems’ (Rittel & Webber 1973). Wicked problems are typically complicated and entangled in contested social and political situations (Funtowicz &

Ravetz 1993). Often, there is confusion about what might be causing a wicked problem. There can be difficulty formulating a clear problem statement and even less agreement around how these sorts of problems might be resolved. Some current wicked problems in our society include the need to realise sustainable urban transport or development, the equitable

management of inland waters and catchments, the maintenance of biodiversity, the positioning of municipal waste facilities, reducing the incidence of childhood obesity and comprehending and preparing for global climate change.

101 Before delving into what sustainable engineering entails, it is important to understand what ESD is and where the idea came from. Today, the term ‘sustainable’ is widely applied. A football coach might describe the team’s losing streak as ‘just not sustainable’, or a politician might pledge ‘a strong, sustainable health care system for all New Zealanders’. In these cases, the term is being used as an extension of one of the range of meanings attached to its base word ‘sustain’. Sustain can mean: to support or bear the weight of for a long period, to give strength or nourishment to, to undergo suffering, to endure or withstand, to uphold or decide in favour of, and to go on relatively unchanged for a long time (The Australian Concise Oxford dictionary 1992). In the phrase ecologically sustainable development, the term ‘sustainable’

has evolved to have a more specific meaning than the range of meanings that are implied by the base word sustain. It is important to grasp the meaning of ESD because there is now a strong expectation that engineers will implement ESD through their professional work.

Definitions of ESD

The Australian National Strategy for Sustainable Development, which was developed in 1992, acknowledges that ESD can have a range of meanings (Department of the Environment, Water, Heritage and the Arts 2008). Here we present a few definitions of ESD and invite you to consider which of these definitions makes sense to you.

The quote opening this chapter — ‘Sustainability is the art of living well within ecological limits’ — comes from Tim Jackson, who is Professor of Sustainable Development at the University of Surrey, UK. It is a simple definition of ESD but requires some thought on what it means to ‘live well’, and whether all members of the world population might aspire to similar living conditions. Being able to enact this definition of ESD would depend on robust measures of the planet’s ‘ecological limits’ and the capacity to model what impact various engineering options might have on those limits. Similar critical thinking about the following quotes and definitions will help you to make a critically informed choice about how you define (and eventually enact) ESD.

An early report by the World Commission on Environment and Development, Our Common Future (also known as the Brundtland Report) (WCED 1987), defined ESD as

‘[development that] meets the needs of the present without compromising the ability of future generations to meet their own needs’.

The New Zealand Business Council for Sustainable Development (2008) explained sustainable development as a holistic concept requiring the integration of economic growth, social equity and environmental management. Along similar lines, the Australian National Strategy for ESD, on the Department of Environment, Water, Heritage and the Arts’ website (2008), suggested the following definition for ESD in Australia:

using, conserving and enhancing the community’s resources so that ecological processes, on which life depends, are maintained, and the total quality of life, now and in the future, can be increased.

Based on all of these definitions, ecologically sustainable development, or ESD, could be described as development that integrates economic growth, social equity and environmental management, so that ecological processes (on which life depends) are maintained in a state sufficient to meet the quality of life needs of present and future generations.

ecologically sustainable development (ESD) Development that integrates economic growth, social equity, and environmental management so that ecological processes (on which life depends) are maintained in a state sufficient to meet the quality of life needs of present and future generations.

The concept of ESD has its origins in increasing community discontent about the environmental impact of industrialisation following the second Industrial Revolution (1870 –1914).

102 In 1962, author and biologist Rachel Carson’s book Silent Spring was published (Carson 1962). The book is recognised as an early and important catalyst in the modern environmental movement. In this book, Carson uncovered a trail of chemical poisoning that led back to use of the agricultural chemical DDT in the United States. The US author had noticed the

spectacularly noisy ‘dawn chorus’ — in which thousands of birds sang together at the start of spring days — appeared to be diminishing. Her book was a wake-up call about the flow-on effects of broad scale use of bio-accumulating herbicides and pesticides.

In the 1970s, advances in mass media and telecommunications allowed environmental activists to bring their concerns about environmental damage to a national and international audience. The next Spotlight discusses a dispute over Lake Pedder, Tasmania. Although the picturesque lake was dammed (and damned), the dispute increased public awareness about the importance of environmental issues.

spotlight