Clemens Deilmann

Climate change: lessons from Germany

Extreme events of floods and tornadoes are a theme in magazines, journals and research in Germany. However, almost no published discussions can be found on the effects on the built environment from overall shifts in average temperatures, rainfall, ground-water tables, humidity, radiation, etc. After having reflected on the different papers, it is clear that the Building Research & Information special issue ‘Preparing for Climate Change: Adapting the Built Environment’ (2003, 31[3–4]) delivers an important contribution. It provides a preliminary idea of country and region-specific peculiarities on climate change due to the geoand topographical conditions of the countries. It also provides an overview on different policy approaches taken to present and anticipate problems in the built environment caused by climate change.

The Efficiency of Settlement Structures

The anthropogenic stock of nations accumulates from year to year materials (metals, plastics, glass, concrete, stones, etc.) for all sorts of durable goods. Some materials might be recycled and used as secondary raw material for new products. But the input into the anthropogenic stock is even in “old” developed economies with ambitious recycling targets five times larger than the output. The anthropogenic stock of Germany grows by 550 million tons per year. The building activities are responsible for almost 85% of a nation’s material flow of all durable goods with life expectancy longer than 1 year. In view of the projected urbanization until 2050—a doubling of urban population according to UN estimate from 3 to 6 billion people—the material input into the built environment is a key issue with regard to our material resource use in the future. After a brief explication of terms, the paper introduces the method of Material Flow Analysis of Urban Form. It stipulates, that only a bottom-up approach, which analyses and models the different patterns of land development along with building types, can deliver the information necessary for a more resource efficient way of urban development. The settlement structure can vary considerably in terms of material input per service unit and the urban structure predetermines for a long time span, how expensive maintenance of surfaces of built assets, interaction, transport, social, and technical infrastructure will be. Two examples of research findings generated by the approach are presented (infrastructure efficiency and costs; recycling potentials along different paths of building activity in Germany).

Physiognomie des Urbanen

Die physischen Auspragungen der Stadt sind bauliches Resultat aus wirtschaftlicher Aktivitat, Planung, Verwaltung, Politik, Konsum. Die Physis ist „sedimentierte“ Geschichte im wahrsten Sinne des Wortes. Zugleich ist die Physis selbst Wirkfaktor fur stadtisches Leben, ist Grundlage okologischer und okonomischer Leistungsfahigkeit, die sich in Kennzahlen wie Bruttowertschopfung, Verkehrsleistung, Bodenversiegelung oder in der Biodiversitat ausdruckt.

Effizienzbewertung von Städten auf der Grundlage von Data Envelopment Analysis

Efficiency aims among others to achieve with the same effort the maximum benefit. For measuring the efficiency of products and processes there are various economic models. This raises the question, whether and to which extent such models can be used to measure the efficiency of cities. In this context, the Data Envelopment Analysis (DEA), commonly used in the field of economics production, has been tested to its applicability to cities. The DEA is a nonparametric, deterministic method to measure the efficiency of economic production, in which the relative efficiency of decision units (DMU) is calculated. In the presented investigation, 116 urban municipalities in Germany were taken as DMUs of the DEA. A discussion about possible values to indicate efficiency of the cities in conjunction with first calculation tests led to a model, by which the economic and the ecological point of view is calculated separately by DEA. Hypotheses were established for both perspectives. Central assumption was: In the economic and ecological model we are looking for cities with least input of the resource “land use” and with high economic resp. ecological performance on output side. The selected input and output values are indicators to deliver an image of prospected correlations. The results allowed a ranking related to economic and ecological efficiency of cities as well as an assessment of the proportions of economic and ecological efficiency of the analyzed cities, realised with the aid of a nine-area-matrix (portfolio). The analysis showed that small and middle sized cities with low population, a medium settlement density and land productivity per unit area as well as a high ecological performance will meet the chosen efficiency criteria most likely. Based on the experience with these still very simple models, DEA appears to be an inspiring heuristic instrument for the attempt to draw near to a concept of an efficient city. English Title: Assessment of the efficiency of cities by using Data Envelopment Analysis