MET matrix

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What is a MET matrix?

Figure 1: MET matrix.[1]

Every product has a certain impact on the environment in terms of pollution, taking up resources, energy use, and waste. A MET matrix is a tool to analyse the product’s impact on the environment throughout its lifecycle. The MET matrix is a means of organizing an analysis of all the types of environmental problems that a product could cause. The principle behind a MET matrix is that it establishes an environmental profile of a product by analysing the product throughout its entire life, using the product lifecycle as a basis. Furthermore, the MET matrix assumes a product to be a system.

The letters MET stand for Material cycle, Energy use and Toxic emissions. The power of the matrix is that it helps to focus on all stages of the product life cycle (vertically) and on the various environmental effects (horizontally) a product has in the subsequent life cycle stages. To prevent stumbling over the complexity of environmental effects, the environmental problems are grouped into three main areas: the Material cycle (input/ output), Energy Use (input/ output) and Toxic Emissions (Output).

The product life cycle has been divided into five life cycle stages: production and supply of material and components, in-house production, distribution, utilization (including operation and servicing), and end-of-life system (including recovery and disposal). In the matrix the distribution stage is presented only once, representing all distribution stages in the product life cycle.

When can you use a MET matrix?

A MET matrix can be used in the idea generation stage or in the concept development stage as a tool to analyse the product’s impact on the environment. The tool helps to uncover areas where the product might be improved to become more sustainable or environmentally friendly. The MET matrix can also be used as an analysis tool in the first stage of a design process, analysing existing products (from competitors) to obtain a competitive advantage.

How to use a MET matrix?

Starting points

The starting point of a MET matrix is a product idea, product concept, or existing product.

Expected outcome

The expected outcome of a MET matrix is a good understanding of the product’s impact on the environment in terms of materi­als used, energy consumption and toxic emissions. This understanding will lead to new insights into how the product might be improved.

Possible procedure

  1. Define what exactly belongs to the product system being studied and what does not. For ecodesign it is essential not to focus on the physical product only, but to consider also the product and consumables which are necessary for the product to function properly over its total lifetime. Especially when comparing two or more products or concepts it is essential to define system boundaries that make them truly comparable.
  2. Perform a needs analysis with respect to the product system just defined. How does the actual product fulfill the needs it is meant to fulfill? Can a product system be developed that fulfills the same needs in a radically more effective and efficient way?
  3. Make a functional analysis, using the MET matrix. A functional analysis starts with a discussion of the product’s functionality, its weak and strong aspects (which parts or functions tend to cause the product to fail), the product’s actual lifetime and its energy consumption. The product is then taken to bits, the weights of the various sub-assemblies and components are measured, the type and amount of materials and components used are listed, and the connections between them identified.
  4. Fill in a MET matrix:
    This column is intended for notes on environmental problems concerning the input and output of ma­terial. This column should include figures about the application of materials which are non-renewable or create emissions during production (such as copper, lead and zinc), incompatible materials and inefficient use of non-reuse of materials and components in all five stages of the product life cycle.
    Energy use
    In this column energy consumption during all stages of the life cycle is listed. Include energy con­sumption for the product itself, and of transportation, operating, maintenance and recovery as well. Inputs of materials with extremely high energy content are listed in the first cell of this column. Exhaust gases produced as a result of energy use are included in this column.
    Toxic emissions
    The last column is dedicated to the identification of toxic emissions to land, water and the air in the five life cycle stages.

Tips and concerns

  • To avoid any environmental impact, use the EcoDesign checklist. This checklist will ensure that the project team asks the most relevant questions related to the product life cycle.
  • To perform the functional product analysis systematically, you should fill out the MET matrix for the main product, considering its environmental effects on all stages of its life cycle. Ensure that auxiliary materials used in all stages of the life cycle are taken into account. If a certain sub-assembly or component turns out to be a serious environmental bottleneck, it can be investigated in a separate MET matrix.


  • H. Brezet and C. van Hemel (1997) EcoDesign: A promising approach to sustainable production and consumption, UNEP, France.
  • H. Remmerswaal (2002) Milieugerichte Productontwikkeling, Academic Service, Schoonhoven.


  1. H. Brezet and C. van Hemel (1997) EcoDesign: A promising approach to sustainable production and consumption, UNEP, France.
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