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Sakari Autio, LUAS, 15.9.2010


Materials, Energy, Toxics & Transportation – An assignment/tool to analyze environmental aspects of a life cycle


A product life cycle is a wide concept, and analyzing the concept is the first step towards commanding the load factors associated with the different stages of the life cycle. Companies are often very familiar with the environmental issues which are directly connected with their own production sites, such as waste management and energy consumption. However, they can be less aware of environmental questions connected with other stages of a product life cycle, for example raw material production or the using stage.

The METT+ matrix may be helpful when you want to examine the factors causing environmental load during the entire life cycle of a product. The METT+ matrix can be defined as a qualitative life cycle analysis method, which in its extensive form requires the acquisition and processing of exact numerical data. With the help of the METT+ matrix you can describe the different environmental load factors associated with different stages of the life cycle of the product or service.

The letter combination METT+ comes from words Material, Energy, Toxics and Transport. The final "+" part refers to those important wider aspects of the environment and sustainable development which do not clearly come under the other four headings. For example, if a product involves significant aspects connected with biodiversity or social sustainability, they can be included in the + group. You can often see the kind of analysis similar to the matrix in other contexts, where product-related environmental data is presented. Usually these more simple types of the this matrix, called MET, are introduced.

In the METT+ matrix a product life cycle can be divided row by row into five stages: 1. production of raw materials, 2. manufacturing of the product and its components, 3. distribution/selling/storing of the product, 4. using the product and 5. at the end of the product life cycle, the possible recycling of the materials, disposal in a landfill or incineration. The matrix can be modified as required; for example the manufacture of the product can be divided into more stages.

So the matrix consists of horizontal rows describing the life cycle stages, and columns according to the METT+ analysis. The purpose is to fill the matrix with information on different factors causing environmental load. It also helps to recognize the missing parts of the information – how well you are able to cover the entire life cycle with environmental data. The usefulness of the matrix largely depends on how detailed the data is and whether it helps to analyze the significant environmental aspects of the product life cycle, as well as the development measures associated with them. With the help of the matrix you can study the input and output factors of the production and use of a particular product.

The method first requires that you determine the product itself and the limits of its system. In addition to the product, it is important to perceive the rest of the product system connected with it, which is the combination of the other products and services required by the operation and use of the product during the whole of its life cycle. For example a mobile phone soon stops operating without a charger, not to mention electricity or power station. What does the product system of the shirt you are wearing involve? The question is where to put the limits of the product system being studied. You have to make and justify the decision concerning the limits based on how much time and resources you can use for the METT+ analysis.

It is not always possible or necessary to make a detailed assessment of a whole product or its life cycle. The resources and available data determine the extent of the assessment. Sometimes it may be sufficient to examine and report on the environmental impacts of just the improved part of the product or some single life cycle stage - But be carefull with this because the partial improvemnts may cause significant negative impacts in some other part of the life cycle.  

Using the METT + matrix

The stages of the product life cycle can be divided into as detailed parts as necessary using the horizontal rows of the matrix. Sometimes it may be necessary to separate the manufacturing processes of the raw materials and components from each other and assess them apart. The matrix can be filled either with quantitative data (e.g. '10 tn VOC emissions') or with qualitative data (e.g. 'significant VOC emissions at the manufacturing stage'). In the case of transportation you can measure kilometers by the different means of transportation or then in the first hand you can handle this issue by defining the distances into domestic/Europe/Global gategories. If you succeed to get the enough information about the transportation then you can combine the volume and distance of the transportation by counting tonn kilometres (tnkm). 

METT+ matrix Materials: inputs/outputs, significant volumes, renewables, recycling, waste
--> What material issues are environmentally significant? Why? 
Energy: inputs/outputs, volumes, renewables?

--> What energy issues are environmentally significant? Why?
Toxic substances, emissions

--> What toxicity issues are environmentally significant? Why?
Transportation, volumes + distances, means of transportation
 --> What transportation issues are environmentally 
significant? Why?
+ Other environmental issues related to the case
--> What is environmentally significant? Why?
Production of raw materials and components          
Manufacturing the product
Storing, distribution, selling
Using the product,
Final stages of the life cycle, recycle, waste management

Figure. An example of the basic METT+ matrix

Filling the matrix with data

(Proposal: Your can divide this assignement for different working groups so that one would concentrate for example on material issues or some specific part of the matrixs.)

Materials column (material balance)

It is a good idea to find out the product's material information (quality and quantity). This information can also be utilized in other contexts, for example if there is an intention to apply for an environmental label for the product. Environmental data associated with product materials can be collected from the company in question, environmental product declarations available, environmental licenses of companies, BAT documents, life cycle studies, etc. You may be able also to consultate with specialists of different materials in your university.

In the materials column you collect data on materials made of renewable and non-renewable natural resources. Name the materials causing environmental problems by releasing emissions during production (e.g. copper, lead). In addition, you analyze the recycling of materials and the quality and quantity of the materials that end up in landfills or incineration.

Energy column (energy balance)

In the energy column you fill in the energy consumed / generated in the manufacture, use and disposal of the product. It is also good to collect information on the production methods of the energy used; are renewable energy sources used? The materials or life cycle stages that consume a lot of energy are marked in the column.

Toxic emissions column

In this column you mark all the toxic substances and emissions released to the ground, water and air during the product life cycle.

Transportation column

For example about raw materials it is good to find out if they are of domestic origin, or whether they are transported from Europe or some other continent. It would be good to collect quantitative transportation data or estimates of different means of transportation (e.g. truck, train, ship) in different stages of the product life cycle.

The "+" column

The "+" part collects those important wider aspects of the environment and sustainable development which do not naturally come under the other four headings. For example, if a product involves significant aspects connected with biodiversity or social sustainability, they can be included in the + group.

How to utilize the data in the matrix

All the data collected in the matrix is analyzed and the main environmental load factors of the different life cycle stages are determined. In addition, you can determine areas for development for example based on which aspects the company can influence on and whether it is possible to find some solutions that are better for the environment. The matrix does not contain a straightforward method for estimating the significance of different load factors. This is a method with the help of which you can create an overall idea of the factors behind the environmental load caused by the product. Often this is enough to help the company to outline product and production solutions that are better for the environment. The matrix helps the company to become aware of those life cycle stages of their products that they have not had enough previous knowledge of and therefore have to pay more attention to in the future.

Checklist of things to pay attention to when doing a METT +assessment

(Please add new questions to the list when possible!)

What kind of environmental problems may occur in the acquisition and manufacture of the materials and components?

  • How much and what kind of plastics and rubbers are used in the product?- How much and what kind of additives are used in the product?- How much and what kind of metals are used in the product?- How much and what other materials are used in the product (glass, ceramics, etc.)?- How much and what kind of surface finishing is used?- What kind of environmental impact do the components have?- How much energy is consumed in transporting the components and materials?

What kind of problems may occur in your company during manufacture?

  • How many and what kind of manufacturing stages are there?- What kind of auxiliary materials are needed and how much?- How much energy is consumed?- How much waste is produced?- How many products do not meet the set quality requirements?

What kind of problems may occur during transportation?

  • What kind of transportation packages does the company use (transport packing, bulk packages, retail packages)?
  • Are the packages reusable?
  • How big is product loss in connection with distribution, storing and selling?- How is transportation arranged – what is the means of transportation?- Is transportation organized efficiently?

What kind of problems may occur during the use, service and repair of the product?

  • What are the main and auxiliary functions of the product? What is the product needed/used for? What benefit does it bring?
  • Does the product carry out these functions efficiently?
  • What kind of user needs are directed towards the product at the moment?
  • Could the functions of the product be improved so that they would meet the needs better than previously?
  • How much energy does it take to use the product?
  • What is the technical operating life of the product? Is the product durable?
  • Which parts or operations of the product fail most often/first?
  • What is the esthetic life of the product?
  • How much service and maintenance is needed?
  • Is the product easy to service?

What kind of problems may occur in connection with the reuse and disposal of the product?

  • Is it possible to disassemble the product without special knowledge and skills?- Can the materials and components be reused? If so, are they actually reused?- Which parts could be reused?- Can the components be taken apart without damaging them?- What materials can be recycled?- Is it possible to identify the materials?- Can you detach the different materials with little effort?- Do the surface finishing or other treatments make recycling difficult?- Is it easy to remove the toxic or harmful parts?- Does the burning of the parts that are not suitable for recycling cause problems?
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