Material flow accounts provide an important basis for the derivation of environmental indicators and indicators for sustainability (Berkhout 1999; Jimenez-Beltran 1998; IME 1999). In order to monitor and assess the environmental performance of national and regional economies, a variety of indicator systems have been proposed (Moldan et al.
1997). The Driving Force-Pressure-State-Impact-Response (DPSIR) scheme was estab- lished as a framework (EEA 1999a, 1999b; OECD 1998a). (It had been used since the early 1990s as ‘PSR’ by the OECD.) The extraction of resources on the input side and the release of emissions and waste on the output side relate to environmental pressures, (sec- toral) activities represent driving forces. The flows may change the state of environment which gives rise to various impacts and the societal or political response may influence the metabolic situation towards sustainability.
Corresponding to the different objectives in Table 8.1, indicators may focus on the specific impact per unit of flow (for example, emission of substances contributing to
global warming) or on the volume of flows which exert a certain generic pressure (for example, consumption of water, energy, materials). MFA-based indicators have been introduced in official reports to provide an overview on the headline issues of resource use, waste disposal and emissions to air and water as well as eco-efficiency (EEA 2000;
UKDETR 1999, Hoffrén 1999).
On the one hand, economy-wide material flow accounts provide a more comprehensive picture of the industrial metabolism than single indicators. On the other hand, they can be used to derive several parameters which – when taken in time series and for international comparison – provide certain aggregated information on the metabolic performance of national or regional economies (Figure 8.1). First international comparisons have been provided on input and resource efficiency indicators by Adriaanse et al. (1997) and on output and balance indicators by Matthews et al. (2000). (See also Chapters 15 to 17.)
Input Indicators
Direct material input (DMI) measures the input of used materials into the economy, that is all materials which are of economic value and used in production and consumption activities; DMI equals domestic (used) extraction plus imports. Materials which are extracted by economic activities but that do not normally serve as input for production or consumption activities (mining overburden and so on) have been termed ‘hidden flows’
or ‘ecological rucksacks’. Hidden flows (Adriaanse et al. 1997), or rucksack flows (Schmidt-Bleeket al. 1998; Bringezu et al. 1996) comprise the primary resource require- ment not entering the product itself. Hidden flows of primary production are defined as unused domestic extraction or ‘indirect material flows’ (Eurostat 2000). Hidden flows of imports equal unused and used predominantly foreign extraction associated with the pro- duction and delivery of the imports. These are not used for further processing and are
Domestic Processed Outputs (DPOs) (to Air, Land, and Water)
Domestic Hidden Flows Domestic
Hidden Flows Domestic Extraction Domestic
Hidden Flows
Imports Exports
Add. Air and Water
Water Vapour
Stocks Economic Processing
TDO DMI
TMR
Domestic Environment Source: Matthews et al. (2000).
Figure 8.1 Economy-wide material flows
usually without economic value. DMI plus unused domestic extraction comprises total (domestic) material input.
Total material requirement (TMR)3includes, in addition to TMI, the upstream hidden material flows which are associated with imports and which predominantly burden the environment in other countries. It measures the total ‘material base’ of an economy, that is the total primary resource requirements of the production activities. Adding the upstream flows converts imports into their ‘primary resource extraction equivalent’.
Data for TMR and DMI (including composition, that is input structure of the indus- trial metabolism) have been provided for China (Chen and Qiao 2000), Germany, the Netherlands, Japan, USA (Adriaanse et al. 1997), Poland (Mündl et al. 1999), Finland (Juutinen and Mäenpää 1999; Muukkonen 2000; FME 1999) and the European Union (Bringezu and Schütz 2001). DMI is available for Sweden (Isacsson et al. 2000). Work is going on for Italy (de Marco et al. 1999) and Amazonia (Machado and Fenzl 2000). TMI, although termed TMR, has been accounted for in Australia (Poldy and Foran 1999).
Output Indicators
Domestic processed output (DPO) represents the total mass of materials which have been used in the domestic economy before flowing into the environment. These flows occur at the processing, manufacturing, use and final disposal stages of the economic produc- tion–consumption chain. Exported materials are excluded because their wastes occur in other countries. Included in DPO are emissions to air from commercial energy combus- tion and other industrial processes, industrial and household wastes deposited in landfills, material loads in wastewater, materials dispersed into the environment as a result of product use (dissipative flows) and emissions from incineration plants. Material flows recycled in industry are not included in DPO.
Total domestic output (TDO) is the sum of DPO and disposal of unused domestic extraction. This indicator represents the total quantity of material outputs to the environ- ment released in domestic territory by economic activity.Direct material output (DMO) is the sum of DPO and exports. This parameter represents the total quantity of direct material outputs leaving the economy after use, either into the environment or to the rest of the world.Total material output (TMO) also includes exports and therefore measures the total of material that leaves the economy; TMO equals TDO plus exports.
Consumption Indicators
Domestic material consumption (DMC) measures the total amount of material directly used in an economy, excluding hidden flows (for example, Isacsson et al. 2000). DMC equals DMI minus exports.
Total material consumption (TMC) measures the total primary material requirement associated with domestic consumption activities (Bringezu et al. 1994). TMC equals TMR minus exports and their hidden flows.
Balance Indicators
Net additions to stock (NAS) measures the physical growth rate of an economy. New mate- rials are added to the economy’s stock each year (gross additions) in buildings and other
infrastructure, and materials incorporated into new durable goods such as cars, industrial machinery and household appliances, while old materials are removed from stock as buildings are demolished, and durable goods disposed of. NAS may be calculated indi- rectly as the balancing item between the annual flow of materials that enter the economy (DMI), plus air inputs (for example, for oxidization processes), minus DPO, minus water vapor, minus exports. NAS may also be calculated directly as gross additions to stock, minus the material outputs of decommissioned building materials (as construction and demolition wastes) and disposed durable goods, minus materials recycled.
Physical trade balance (PTB) measures the physical trade surplus or deficit of an economy. PTB equals imports minus exports. Physical trade balances may also be defined including hidden flows associated with imports and exports (for example, on the basis of TMC accounts).
Efficiency Indicators
Services provided or economic performance (in terms of value-added or GDP) may be related to either input or output indicators to provide efficiency measures. For instance, GDP per DMI indicates the direct materials productivity. GDP per TDO measures the economic performance in relation to material losses to the environment. Setting the value- added in relation to the most important inputs and outputs provides information on the eco-efficiency of an economy. The interpretation of these relative measures should always consider the trends of the absolute parameters. The latter are usually also provided on a per capita basis to support international comparisons.
Increasingly, MFA and its indicators will be used to provide the basis for political meas- ures and to evaluate the effectiveness of such measures. For that purpose bulk material flow analyses and substance flow analyses can be combined and the monitoring of progress towards sustainability can be gradually improved by taking a stepwise approach (see Bringezu et al. 1998a).
NOTES
1. The indicative value depends on the relation to (a) other flows, (b) assessment parameters such as critical levels, and (c) system properties of the accounting (for example, systems borders from cradle to grave) (Bringezu 2000a).
2. To conform to LCA usage, attribution is sometimes called ‘allocation’.
3 In studies prior to Adriaanse et al. (1997), TMR had been defined as total material input, TMI (for example, Bringezu 1997b).