Environmental assessment of construction products


Life cycle assessment data, in particular the calculation of effect assessment data, such as the volume of greenhouse gas emissions, are an important aspect for the ecological assessment of buildings. The environmental accounting of construction products delivers detailed and objective key figures, based on which the path of the product from its manufacture via the utilisation phase until the disposal or reuse can be evaluated. The basis for this data collection is the DIN EN ISO 14040, which divides the building into its individual parts by a comprehensive and independent picture of building products and their environmental impacts, and then submits each part to a separate inspection. KLB-Klimaleichtblock has corresponding environmental assessment verification for its lightweight concrete bricks.

Advantages of Life Cycle Assessment

  • Identification of optimisation potentials / comparison of alternatives
  • Information basis for product and process developments in the industry
  • Creation of base indicators for capturing and measuring environmental impact
    (for example basic principles for environmental product declarations, abbreviated EPDs)
  • Development of marketing potentials via reliable environmental statements regarding the building product.

The structure of a life cycle assessment results from the four phases of its creation:

  • Definition of the goal and the examination framework
  • Life cycle inventory of resource use and emissions of the product system
  • Assessment of the environmental impacts of all input and output flows
  • Evaluation of the acquired data


The first step is to define which purpose the life cycle assessment should fulfil for the company. For example, it can serve as basis for a comprehensive environmental product declaration (EPD) or also “only” indicate energy savings potentials in manufacturing. So it can make sense to exclude life cycles of the product if they are irrelevant for the evaluation. In addition to these system boundaries different impact categories are needed, in which measurements are taken based on functional units.


The “Life Cycle Inventory” (abbreviated LCI) of the building product represents the second step for the life cycle assessment. It follows the entire life cycle with regard to all material flows. This encompasses inputs and outputs from the material and possible auxiliary materials, electricity and heat as well as resources and emissions. To be able to guarantee comparability with other products, the individual aspects of environmental impacts must be quantified using measurable number values.


Subsequently the impact assessment (Life Cycle Impact Assessment, abbreviated: LCIA) can take place as the third step. It provides a classification of the results from the life cycle inventory by attributing the number values to specific impact categories. Each of these categories is assigned one or more impact indicators. This characterisation then specifies, for example, that for the category "global warming potential" the environmental impacts of all relevant gases must be indicated using the indicator "CO2 equivalents". Optionally, in conclusion a weighting of the individual impact categories versus each other can take place.



In the fourth phase the results from the life cycle inventory and the impact assessment are summarised and evaluated. However, any recommendations that can be derived from this are always based on potential, non-actual environmental impacts. Specifically for thecreation of environmental product declarations these insights are extremely helpful though. In order to be allowed to use the EPDs at the end as communication instrument for life cycle assessment data, the data must be verified in accordance with ISO 14025.


For the central collection of the life cycle assessment data the so-called ÖKOBAUDAT is used. This online database is the first of its kind to meet the requirements of DIN EN 15804 and is characterised by high data quality. In it are life cycle assessments of building products and processes, which can easily be accessed for the life cycle assessment of the entire building. Of course, the database also includes corresponding data for light-weight concrete masonry.