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3. Ecological Rucksacks and MIPS
3.1 Ecological Rucksacks
Schmidt-Bleek thinks that, in each product or service that we use, we are carrying "in a rucksack" the materials that were moved from their locations in nature to make the goods or services. These are called ecological rucksacks (Figure 1). The ecological rucksacks indicate the amounts of materials that were moved in nature to make the goods, and so the ecological rucksacks represent the degree of stress exerted by the goods on the environment.
The ecological rucksacks of goods are easily calculated. All materials used in the production of goods are listed by weight and multiplied by rucksack factors, and then summed to include all materials. |
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Here, MI is the ecological rucksack or material intensity, and Mi is the weight of the material in terms of kilograms, and Ri is the rucksack factor. Figure 2 shows the process for calculating ecological rucksack of an automobile.
The rucksack factor (or MI factor) is the amount (in kilograms) of materials moved to obtain 1 kilogram of the resource. For example, Steel: 21 (One kilogram of steel carries an ecological rucksack of 21 kilograms.), Aluminum: 85, Recycled Aluminum: 3.5, Gold: 540,000, Diamond: 53,000,000, Rubber: 5.
The rucksack factors for the main essential materials necessary for economic activities have been studied at the Wuppertal Institute.
3.2 MIPS
MIPS is the material intensity per unit service or per unit function with respect to the entire product life.
Energy consumed during the entire product life is also taken into account. MIPS are thereby defined for service-yielding, final goods. The material transportation and energy requirements for the entire product life are also taken into account.
It is now possible to show how material requirements are divided over the various process steps of the life of a service-yielding final good, including the process of manufacturing, using (operating, maintaining, cleaning), repairing, re-using (perhaps using only component parts), collecting, sorting and disposing the good. Additionally, transportation enters the calculation as an almost ubiquitous link between various steps. This is then related to the total number of deliverable (or, in hindsight, delivered) use, function or service units.
In the case of non-reusable packaging material and throwaway products (which actually vanish in landfills and are not used for other purposes), the "S"(Service) of MIPS is equal to one. The MIPS value in this case is equal to the aggregate amount of material for all process increments.
The MIPS value decreases as the number of service units delivered by the product rises. Each successive service unit cuts in half the value of MIPS achieved with the previous use. The MIPS value thus shrinks with each successive use, and the environmental compatibility of the product improves in step.
A sundial is the simplest example. Here, neither material nor energy is required at any time during the use of the device, and it is never cleaned. The device never needs any extra material during its service life, and so its MIPS decreases continuously.
In the case of a washing machine, the MIPS curve falls more slowly because water, energy and detergent are used in each wash cycle. If the use of water and energy rises with the age of the machine, the curve might even reach a minimum, after which it would start to rise again. If a repair becomes necessary (figure 3, point X), we have a "MIPS stimulus," after which the curve begins to fall again. A repair that is very "expensive" in terms of material, energy or transportation (point Y) can lead to a situation in which the machine is operating at a higher MIPS value than when it was new. This would be an example of an ecologically absurd repair-if MI (the material intensity) for the distance Y-B were greater than for O-A. (In other words, if the MI value of the repaired machine is higher than the original MI value of the new machine.)
The MIPS value is calculated as follows: |
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MI is the ecological rucksack.
"S" is the service number, and represented as Sn. p.
"n" is 1 for consuming products, and n is the number of times of usage or the amount of usage , for example, hours or surface area for durable consumer goods .
In the case of a cup of orange juice, S=1. If a person uses a bicycle for n kilometers, S equals n.
If p persons use a train for n kilometers, then S equals nEp.
3.3 The relationship between MIPS and resource productivity
We are now concerned with the question of defining resource productivity as carefully as possible, so that it can increase its status as a criterion for economic and technical decision-making.
The resource productivity of each goods is the total sum of available service units, divided by the total consumption of material for the service-yielding good, as calculated from cradle to grave, including the material flows needed for the purpose of providing the requisite energy. In other words, the resource productivity of a good is the inverse of its MIPS, and is measured in "per kilogram" terms.
Resource productivity is also called eco-efficiency. The material wealth of a region could then be expressed in terms of the number of service units available there. If resource productivity rises while material consumption remains the same, material wealth increases. In other words, "dematerialized" technologies can yield more service units with constant of falling material effort. Were one to increase the global resource productivity fourfold, it would be possible, under this definition, to double the number of service units and have the material inputs cut in half. Dematerializing in economic terms does not mean moving back to lower consumption; it means progress, as such a development would not be possible without concomitant technical improvements. We can refer to this as a technical approach to a sustainable economy.
3.4 What MIPS can-and cannot-do
From a technical perspective, the use of the MIPS has the following advantages:
| 1) |
Material and energy expenditures are measured in the same units. In so doing, contradictions in ecological evaluation are avoided, and the evaluation becomes directionally stable. |
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The concept can be used to set up Life Cycle Analysis at the level of screening procedures. The effort involved in the analysis is hereby dramatically reduced, and the results become directionally stable. Decisions about successive analyses can follow in the form of a phased plan. |
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The concept can serve as an instrument with which to test the ecological significance of technical procedures in light of their contribution toward a sustainable economy, as well as for measuring attendant successes. |
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The MIPS approach helps in the design of industrial products, in the planning of environmentally friendly processes, facilities and infrastructures, as well as in the ecological assessment of service. |
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The concept can serve as the basis for a comprehensive ecological labeling strategy, and can be an aid in purchasing decisions and consumer counseling. |
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The MIPS approach is suitable as a tool for distinguishing ecologically sensible recycling loops and circulation systems from those that are ecologically absurd. |
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The approach can be used to establish ecological tariffs, issue licenses, set insurance premiums, assess taxes, and to make decisions about subsidies. |
| 8) |
The concept is suitable for examining various codes and standards for their ecological coherence. |
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The MIPS concept can help make decisions about what kinds of research and development projects deserve financial support. |
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The MIPS approach should be well suited to assessing technical projects which are part of development aid to the Third World, and for the former socialist countries, with respect to their environmental characteristics. |
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The concept shows promise in the context of future international harmonization because of its simplicity. This would be important for the possibility of making progress toward ecological structural change on the level of major regions such as the European Union, or worldwide. |
The concept cannot cover the following problems.
| 1) |
The concept does not take into account the specific "surface-use" for industrial as well as for agricultural and forestry activities. This is of considerable importance as the amount of the earth's surface available for our purposes is limited. |
| 2) |
As already indicated, the MIPS approach does not take into account the specific environmental toxicity of material flows. The approach is not intended to supplant the quantification of eco-toxicological dangers of materials in environmental policy, but rather to supplement it by stressing the material and energy intensity of economic services. |
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The MIPS concept makes no direct reference to questions of biodiversity. It seems to speculate that the chances for species survival are related to the intensity of soil and resource use. Therefore, one cannot exclude the notion that the material intensity of a society's economy has something to do with its contribution to species extinction. |
For example, in 1996, Theo Colborn(7) warned that some synthetic materials destroy the hormone system of livings. Problems such as this cannot be addressed by MIPS. It is necessary to combat with toxic materials for human health.
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