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Methodology

First, a set of definitions is given to describe the material fluxes through a regional anthroposphere. Next, these definitions are used for a systems analysis of a region. Third, field data are collected for the flux of selected materials through the most important processes. Finally, material fluxes through the region are calculated, and two examples of how to use these results for the control of material fluxes in the anthroposphere are given.

Definitions

Table 1 Terms used for the analysis of the anthroposphere

Source: Baccini and Brunner, 1991.

In order to investigate the flow of materials through a regional economy systematically, and to use this information for control purposes, we use the following definitions, summarized in table 1 (Baccini and Brunner, 1991):

A material is a chemical element (e.g. lead, carbon) and its compounds (lead chloride, benzene). Material flows are measured in mass per time units, material fluxes in mass per time and area. The "area,' can be an entire region, a household, or a person; hence the flux unit may be in kg/capita and year.

A good consists of one or many materials, such as a pipe made of lead, or gasoline containing benzene. A good has a negative or positive economic value. In the economic sense, goods can also be energy, information, or services. In this work, we apply the term to material goods only, such as cars, water, or municipal solid wastes.

A process is defined as a transport, transformation, or storage of goods, materials, energy, and information. A transport often involves a change in the value of a good. There are processes possible on all levels: a car engine may be looked at as a process, in same way as a private household, a waste incinerator, a branch of a regional economy, or an entire region.

An activity can be defined as a set of processes and fluxes of goods, materials, energy, and information serving a certain purpose, such as to nourish, to clean, or to transport. The concept of "activities" allows one to evaluate different strategies of control. For example, the activity "to nourish," comprising the production, upgrading, storage, distribution, preparation, and consumption of food, involves large fluxes of nitrogen and phosphorus, which may eventually have a negative impact on water, air, and soil. A material flux analysis of the activity "to nourish," from the fertilizer to the edible meal, will thus reveal the most effective measures for the control of these fluxes.

Fig. 3 The anthroposphere as a man-made system (r = resources, w = wastes)

The anthroposphere is the field where human activities take place; it is embedded in the environment (fig. 3). Sometimes called the manmade biosphere, it can be envisaged as a living organism. It has its own metabolism consisting of the uptake, transformation, storage, and discharge of energy, matter, and information. The anthroposphere can be described as a system of processes, and fluxes of goods, materials, energy, and information (see table 1). There are many regional varieties of the anthroposphere, since it is highly influenced by such parameters as the climate, the topography and geology, the native population and its values, the neighbouring regions, and others. The main goal of the metabolism of the anthroposphere is to supply private households with energy, consumer goods, and information; the target process of all anthropogenic activities is the household. All other processes have merely a supporting function.

The method developed to describe the system "region" is based on processes and fluxes of goods and materials (Baccini and Brunner, 1991). Each flux has a "process of origin" and a "process of destination" and thus is precisely defined. Equally, each process is linked with other processes by means of fluxes. A good X, which flows from process A to process B. is called an output good for process A and an input good for process B. An import good is defined as a good which crosses into the region, whereas an export good leaves the region. The same terminology applies to the flux of materials.

As shown in figure 3, a process is graphically presented by a square, a good by an oval, and fluxes of goods or materials by arrows. Although these definitions seem tedious, they become important as soon as one attempts to link the various data about the flux of materials of individual processes. It is very rare for the measurement of the flux of X as an output good to yield the same result as the measurement of X as an input good into the next process. For example, the figure for consumption of drinking water varies by 20-30 per cent depending on whether it is measured at the water supply (output good) or the consumer (input good).

Systems analysis of a region

Description of the region

The region investigated in this work is the Untere Bünztal (Lower Bünz Valley). This broad valley, which is located approximately 400 m above sealevel, covers 66 km², and is limited on both sides by rolling wooded hills. It forms a single watershed, containing two major but small rivers with a water flow of about 0.5-2 m³/sec. Fifty-six per cent of the land area is used for agriculture, 30 per cent is forested, and 13 per cent represents urban areas. The average precipitation amounts to 1,100 mm, and the average temperature is 8-9 °C. The valley may be called representative for regions in Western and Central Europe as well as for the north-eastern United States.

There are 28,000 persons living in the region, in 9,300 private households located in 12 communities. The average per capita purchasing power of US$30,800 (1986) matches that of other regions in Europe. Fifty-nine per cent of the 11,000 employees work in the production sector, 35 per cent in the service and public sector, and 6 per cent in the primary sector (agriculture). Some 55 per cent of the 1,400 enterprises in the region belong to the service sector, and the remaining 45 per cent are equally divided between production and agriculture. Of the 19 branches present in the production sector, the metal industry branch just dominates with 17 per cent of all employees, followed by the plastic and the construction industries with 13 per cent. Other important branches are the electric/electronic industries (11 per cent), textiles (9 per cent), and others (for details see Rist et al., 1989).

The region may be described as a well-mixed economy with an important fraction of its employees working in a few large companies in the production sector, such as a steel mill and a chemical company.

Analysis of the system

Establishing a systematic and comprehensive regional material balance is a comparatively new undertaking. Hardly any methods and data exist for materials accounting on the local level. For the time being, it is beyond the capacity of any research project to investigate the total material flow of a region; the number of goods and materials (elements and compounds, especially of organic carbon), as well as the number of processes, is far too large. Thus, the art of regional materials accounting is to find the few processes and goods which determine the overall flux of a particular material. The following approach was taken in order to simplify the system "region."

As a first step in designing the systems analysis on a general level, the region can be divided into eight major processes. The next step is a more detailed investigation and a subdivision of each of these processes into subprocesses.

A rough assessment of the most abundant fluxes of goods through private households reveals that about 80-100 t/c/yr of goods flow through an average household (see fig. 1; Brunner and Baccini, 1992). Most of these goods originate from the public services (water, natural gas) and the service sector. The production sector supplies the matrix of the regional anthroposphere, such as buildings, roadways, and the nutrients (food) and energy (fuel) to be distributed by the service sector. A few companies with either a large number of employees or a high (financial) turnover are expected to be important for the flux of goods in and through the region. In order to find these important companies, a detailed knowledge of the region is indispensable.

A valuable tool for this work was an existing database about the places of work and the businesses for each sector and branch in the region. When this database was combined with information about the average financial turnover of places of work, a rank order of the importance of the 1,400 businesses in the region became possible. Of course, a rank order according to such economic criteria is not congruent with a ranking based on the fluxes of goods or materials. In the absence of any such information in the production sector, the economic ranking was useful as a first approach - somewhere to start the survey. One advantage of including economic information in this study was that it opens up the possibility of combining material flux data with net product data, and thus serves as a first approach to the problem of linking ecology and economy.

On the basis of this preliminary investigation, the following five most important processes have been defined in the regional anthroposphere.

PRIVATE HOUSEHOLDS. This process stands for the many processes which take place in a private home in relation to the activities "to breathe," "to nourish" (e.g. shopping, preparation, and consumption of food), "to reside" (construction and maintenance of buildings, heating, purchase and maintenance of furniture, carpets, curtains), "to clean" (laundry, dishwasher, toilet, shower, car wash, cleaning), and "to communicate" (transport of persons, goods, energy, and information). Included are processes (and goods) which serve exclusively the private household but which take place outside of it, such as the use of a motor vehicle for shopping, the use of a sewerage system to collect sewage from households, or part of the telecommunication network for TV and phone. The process "private households" comprises all 1,300 households in the region.

SERVICE SECTOR. This sector includes all the businesses engaged in trade and commerce (e.g. shopping centres, retailers, grocery stores), financial and personal services (banks, insurance companies), the catering trade (hotels, restaurants), transportation, and others. Its main purpose is to serve the private individuals in households.

PRODUCTION SECTOR. This process comprises all businesses which produce machinery, metals, chemicals, food, textiles, furniture, shoes, vehicles, etc., and includes the construction business. The goods of the production sector are mainly delivered to the service sector. A detailed list is given in Rist et al. (1989).

PUBLIC SERVICES. In economic classifications, the public sector is usually included in the tertiary (= service) sector. For this work, a separate process, "public services," was chosen for the following reasons: In the region investigated, public services are responsible for the largest fluxes of goods, namely the supply of water, the collection and treatment of sewage, and the collection of solid wastes. Also, public utilities supply electricity, natural gas, and telephone services. For all these subprocesses, there are extensive and reliable databases available. Thus, the flux of goods between the "public services" and the "private households" is important and well documented, justifying a separation from other, less comprehensively investigated processes.

AGRICULTURE. This term stands for the processes which are necessary to plant, grow and harvest plants and to raise animals. In a separate project, subprocesses of the process "agriculture" were linked with the processes "atmosphere" and "soil" in order to determine the contribution of the agricultural practice to the material fluxes in the soil system. These results have been published before and are not included in this work (don Steiger and Baccini, 1990).

In order to fulfil the requirements for processes of "origin" and "destination," three synthetic processes were introduced: man-made import and export processes in the neighbouring regions, and a process "environment." These are composed of many subprocesses. For simplification, they have not been included in figure 4.

The following illustrates some of the subprocesses. Private households use the good "air" for the activities "to breathe," "to reside" (heating), and "to communicate" (transportation). The process of origin for "air" is the Planetary Boundary Layer (PBL), which is a subprocess of the process "environment." The process of destination for the offgases is again the PBL. The source of drinking water is the subprocess "groundwater" in the environment; a subprocess "distribution of drinking water" in the public services supplies private households with drinking water. The collected and treated sewage is finally transferred to the subprocess "River Bünz" in the environment.

The most general list of fluxes of goods consists of the ten good categories represented by bold arrows in figure 4. A category of goods may contain a few single goods (such as the flux from the public services to private households, consisting of drinking water, natural gas, and a few more items) or several hundred to several thousand goods (such as the flux from the production to the service sector, or from the service sector to private households). (A complete list of goods is given in Rist et al, 1989.)

Initially, 12 materials were selected for this study. Two elements were chosen for detailed investigations: lead (Pb), which is still used partially as an additive in gasoline, and which is contained in many consumer products such as cars, batteries, curtains, ties, corks, and construction materials; and phosphorus (P), which is an essential nutrient for the biosphere, a widely used ingredient in cleaners and dishwashing liquids, and an important agent to prevent boiler scale and corrosion.

Fig. 4 Systems analysis of the region Unteres Bünztal (B = Anthroposphere of region, N = Anthropospheres of neighbouring regions)

Assessment of fluxes of goods and materials

In order to determine the flow of goods through the anthroposphere of the region, two kinds of methods were used. The process "private households" was characterized by results from existing market research studies, and the other processes were analysed by individual surveys of the most important companies and public utilities. These techniques yield sufficient information about the flux of goods, but are in general not applicable to the collection of data about the flux of materials, since neither private households nor many businesses know the material composition of the goods they use. Thus, information about materials was collected from other sources, such as general tables (Ciba-Geigy, 1977) or specific articles about the content of, say, phosphorus in goods like detergents and fertilizers.

Private households

There is abundant information from market research on the average consumption of most goods in private households in many regions. These data cover short-lived goods such as food, cleaning agents, and newsprint, as well as goods with longer residence times (e.g. appliances, furniture, textiles). However, there was no market research information about the Bünztal available. Hence, data were used from regions with similar per capita income and similar household size, two properties which are known to be significant for the comparison of the consumption in households. The projection for the entire region was made by multiplying the number of inhabitants with the average per capita consumption. The hypothesis that the use of figures from other regions may be applied to the Bünztal was tested by comparing data on basic foodstuffs from various regions; deviations were between 5 and 15 per cent and are considered acceptable.

The example of phosphorus (P) in table 2 illustrates the procedure for determining the material flux through the household. Data about the flux of 54 goods was supplied by a market research firm (IHA); the concentration of P was taken from Ciba-Geigy (1977), and the P-fluxes were calculated by multiplying the flux of goods with its P-concentration.

Table 2 Assessment of the P-flux through the average private Swiss household

Source: Brunner et al., 1990.

Fig. 5 Flux of phosphorus through the process "private household," in g P/c/yr (A = Process kitchen, B = Process dishwashing and cleaning, MSW = Municipal solid waste, STP = Sewage treatment plant)

The results on P-input obtained by this procedure were successfully cross-checked with available data on P-output from waste and sewage management (fig. 5).4 The P-flux of all the households in the entire region was obtained by multiplying the per capita flux with the 28,000 inhabitants of the region.

Production sector, service sector, and public sector

For each of the three sectors, branches such as "production of food and drinks," "manufacturing of chemicals," and "public water supply" were defined according to BAS (1985). The number and size (given as number of employees) of the businesses in each branch were taken from BAS (1987). The largest companies of each branch were selected and asked for interviews. This allowed us, as a first step, to reduce the 1,377 businesses to 102 enterprises with more than 20 employees, comprising 6,632 workers, or 64 per cent of the total of the three sectors. In a second step, 29 enterprises were excluded from the survey because, on the basis of their field of business, their material flux appeared to be rather small.

With the support of the local chamber of commerce 73 enterprises were individually approached and asked to participate in the project. Of these, 38 companies participated fully, and 11 were eliminated because they had very small fluxes of goods, or could not supply the necessary information in time. Of the remaining 24 businesses, 10 construction companies were included as an entity (see below), and 12 were not surveyed because of the limited manpower available for this research. Only two did not wish to participate in the study. As a rough assessment showed the importance of one of these companies (a carshredder), indirect methods were used to estimate the contribution of the shredder to the regional material flux. (This indirect method is based upon the assessment of the material balance before and after a particular process: information about the manufacturing of cars, a material balance of a similar car-shredder in another region, and information about the amount and composition of the automobile scrap metal treated in a regional smelter permits a rough estimate of the flow of goods and materials through the car-shredder.)

In addition to the survey of individual companies, comprehensive data about all construction businesses in the region were obtained from the regional market leader of the construction branch. Detailed information about water consumption, waste-water treatment, waste management, and energy consumption was supplied by the public utilities of the 12 regional communities; it was fortuitous that the systems boundary coincides with the boundaries of the communities. Thus, it was possible to cross-check the figures on overall water consumption against waste-water production, the data on individual waste production against the global figure on waste collection and treatment, etc. By such cross-checking, gross errors can be detected.

Table 3 summarizes the fraction of businesses, employees, and material turnover covered for each branch in the survey. Despite the fact that only a few percentages of all businesses were investigated, it was possible to include a large percentage of all employees and a very high percentage of the total turnover of goods.

The participating companies were interviewed by an engineer and an economist. In addition to questions regarding the business structure (field of activity, employees, most important processes of origin, and destination for the goods used/produced), the following specific data were collected:

- List and annual flux of input goods, including energy.
- List and annual flux of output goods, including wastes such as municipal solid waste (MSW), production of waste, waste water, and flue gas.

Table 3 Fraction of businesses, employees, and turnover of goods included in the survey (percentage surv.)

Source: Own research.

a. In this table, "good" stands for output goods only, and does not include wastes such as municipal solid waste, sewage, or offgas. For most branches turnover was calculated on the assumption that each branch has a specific turnover per employee, but that in some branches (e.g. metal-processing, trade/commerce) the total turnover is heavily influenced by a few companies; cf. Rist et al., 1989).

The information collected varied in its preciseness. In most cases, it was sufficiently detailed to be directly included in the total regional flux of goods. For instance, a chemical company supplied very elaborate data, including hundreds of raw materials and many output goods. Such data have to be aggregated, however, before they can be used. Most companies also provided information about financial turnover, cash flow, and net product.

Calculation method

The information about the fluxes of goods of the "average" private household and of each business was used to calculate a list of the most important processes and of the most important goods in the region (tables 4 and 5). These calculated figures, however, have errors of +/20 per cent: some information is missing (not all processes have been surveyed), the information does not cover the same time period for all businesses, and the data collected are not always accurate because making measurements or calculations is difficult (solid waste) or impossible (flue gas).

The flux diagrams of lead and phosphorus (figs. 6 and 7) were calculated as follows: A material flux balance was established for each process, using measured and estimated flux and concentration data. As not all fluxes through a process were known, some fluxes had to be calculated as difference of inputs and outputs. When all fluxes through a process are measured, it is often not possible to balance inputs and outputs. The balancing period was one year. The change of reservoirs was taken into account for soils and landfills only; annual inputs and outputs of all other processes were considered in equilibrium. The material balance of each single process was then linked to all other processes, yielding an overall regional balance. This procedure required careful validation of the material fluxes through most processes, since the output fluxes of one process and the input fluxes of the following process do not always correspond. In general, most emphasis was put on those large fluxes that are measurable with the least error.

Table 4 Important processes and total flux of goods through the region, including private transportation

Source: Rist et al., 1989.

a. Including private transportation.

Table 5 Most important fluxes of goods (In t/c/yr) and their fraction flowing through private households of the region

Source: Brunner et al., 1990.

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