Building in Use - Environmental aspects

Lifecycle assessment of the building

One aspect of the clay brick ecobalance project based on lifecycle assessments of clay brick factories in several countries was the “cradle to grave” assessment of clay brick wall constructions. This forms an essential part of the overall lifecycle assessment of a whole building.

The results of the evaluation of different clay brick wall constructions were:

• The ecological assessment of buildings must take into account the whole lifecycle of the construction. This covers:
  • Raw material extraction,
  • Manufacture of building materials,
  • Erection of the building,
  • In-use phase,
  • Maintenance and repair,
  • Demolition,
  • Separation and re-use,
  • Removal of building residues.
     
• The choice of heating system and the type of fuel used have a significantly higher influence on the lifecycle assessment than the wall construction and its thermal performance.
   
• District heating from waste incineration has the least impact on global warming whereas electrical heating has the highest impact (but this will also depend on the method of power generation). Natural gas and oil heating fall between these two extremes.
   
• Where heating systems are already highly efficient, the potential to recycle the building’s materials becomes significant in the overall calculation.
   
• Taking these points into account, monolithic clay brick walls and clay brick cavity walls with sufficient thermal capacity achieve excellent results.
   
• The results are more or less independent from the established evaluation model.
   

Ecological lifecycle assessment

The graph above depicts the results of an ecological lifecycle assessment of clay brick wall constructions in terms of GWP (Global Warming Potential) and PEI (Primary Energy Input) for various fuels and heating systems over a period of 90 years.

In reality the choice of energy (electricity, oil, natural gas, renewable energy such as wood or solar heating and district heating) used for heating or cooling can be much more decisive for the ecological assessment of a building than the type of wall construction.

Note: these results can vary significantly from country to country and will depend on the prevailing type of power plant and on the availability of district heating from waste incineration.

Within the Green Building Challenge Project, evaluation tools have been developed to determine the overall ecological lifecycle assessment of a whole building. These models have been implemented in several countries (e.g. “Total Quality” certification in Austria). In France the Démarche HQE is used (see Démarche HQE).

The results of the evaluation for clay brick buildings are very positive.

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