As engineers and scientists it is natural that we should want to tackle problems at a level to which we can bring our skills to bear. The methods described in the previous chapters are examples. They address immediate problems, ones that are already evident and identified. But they do little to tackle the deeper problem: that of long-term sustainability. Figure 10.1 introduces the concept. The horizontal axis describes the time scale, ranging from that of the life of a product to that of the span of a civilization. The vertical axis describes the spatial scale, again ranging from that of the
Intervention to limit P, C and P and control pollution
FIGURE 10.1 Approaches, differing in spatial and temporal scale of thinking, about the industrialization and the natural ecosystem. (Adapted from Coulter et al, 1995)
product to that of society as a whole. It has four nested boxes, expanding outward in conceptual scale, each representing an approach to thinking about the environment.
The least ambitious of these—the smallest box—is that of pollution control and prevention (PC and P). This is intervention on the scale and lifetime of a single product and is frequently a cleanup measure. Taking transport as an example, it is the addition of catalytic converters to cars, a step to mitigate an identified problem with an existing product or system.
The next box is that describing design for the environment (DFE)—the techniques discussed in Chapters 7 through 10 of this book. Here the time and spatial scales include the entire design process; the strategy is to foresee and minimize the effects of product families at the design stage, balancing them against the conflicting objectives of performance, reliability, quality, and cost. Retaining the example of the car, it is to redesign the vehicle, giving emphasis to the objectives of minimizing emissions by reducing weight and adopting an alternative propulsion system—hybrid, perhaps, or electric.
The third box, that of industrial ecology, derives from the precept that we must see human activities as part of the global ecosystem. Here the idea is that a study of the processes and balances that have evolved in nature might suggest ways to reconcile the imbalance between the industrial and the natural systems, an idea known as the ecological metaphor. We return to this idea in a moment as a way of structuring thinking about the last box, that of sustainable development.