Materials Efficiency Metric

The eToolLCD Materials Efficiency Metric was created to calculate material circularity and apply it to a whole asset analysis. The metric is calculated based on the mass of material that is virgin or reused, and the amount of renewable and non-renewable primary and secondary material. After calculating the mass, a discount factor (weighting) is applied to reused materials and materials with higher renewable content. The lower the materials efficiency metric number the better or more “circular” the material is.

eToolLCD users are able to report on the Materials Efficiency Metric as they would normally report on an indicator so that is visible in the same reports alongside other environmental indicators. Material efficiency metric can be calculated at the asset level which takes into account the design life achieved with materials (years). 


For each asset, the materials efficiency should be calculated using the following equation:

MEasset = materials efficiency metric for asset
Mv = mass of virgin material (tonnes)
Mrec = mass of recycled material (tonnes)
Mren = mass of renewable material (tonnes)
Mren+rec = mass of recycled renewable material (tonnes)
Mreu = mass of reused material (tonnes)
Mren+reu = mass of reused renewable material (tonnes)

Each mass of material should include the materials required for any associated temporary use (i.e. those consumed during construction plus the construction waste generated). At design stage, for materials that have variable recycled/renewable/reused content, the industry average rates should be used until the specifications have been confirmed.

eToolLCD Indicators & Processes

Material processes in eToolLCD library were updated to include:

  • Mass of non-renewable primary material (t)
  • Mass of non-renewable secondary (recycled) materials (t)
  • Mass of renewable primary material (t)
  • Mass of renewable secondary (recycled) material (t)
  • Mass of reused non-renewable materials (t)
  • Mass of reused renewable materials (t)

New indicators were added to the eToolLCD for:

  • Total Mass
  • Mass of recycled materials
  • Mass of reused materials
  • Materials Efficiency Mass

These indicators are available only when using eTool default LCI Source but are not available in the IMPACT database. To turn on these indicators when generating the LCA report, please refer to the setting below:

Below is an example of how the material efficiency metric indicators are displayed as shown in page 3 of the LCA report:

Related articles: New Materials Efficiency Metrics, Links between LCA and the Circular Economy, Are we running out of building materials?, BREEAM Mat-06 Material Efficiency


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