Traditionally, architects and engineers were interested in designing new buildings, town planners and political authorities in planning the growth of settlements and cities. Their ideas are still strongly conditioned by the post-1945 boom, which has doubled the building and infrastructure stocks of most European countries. The centre of interest has been in expanding, open systems. But over the last few years, clear new trends have appeared: interest is shifting gradually from managing growth to managing saturated steady-state situations. Indeed, there is also recognition on the need to manage the decline (or shrinkage) of the built environment. In the building context, a stock-centred view replaces the fascination for continuous growth in input flows, and the ignorance of output flows and side-effects. Kenneth Boulding anticipated this shift from ‘cowboy economics to spaceman economics’ more than 40 years ago:

In the spaceman economy, what we are primarily concerned with is stock maintenance, and any technological change which results in the maintenance of a given total stock with a lessened throughput (that is, less production and consumption) is clearly a gain. This idea that both production and consumption are bad things rather than good things is very strange to economists, who have been obsessed with the income-flow concepts to the exclusion, almost, of capital-stock concepts.(Boulding, 1966, p. 11)