2.6. Impact categories
We calculated the carbon and energy footprints. The carbon
footprint is based on the characterisation factors for global warming
potential (GWP) as published by the IPCC 2007 [29] and takes into
account renewable and non-renewable carbon assuming that any
biogenic carbon which is stored in the materials is deducted during
the production phase (cradle-to-factory gate) of a carbon footprint/life cycle assessment. The energy footprint represents the
cumulative fossil and nuclear energy demand in terms of primary,
non-renewable energy use (NREU), i.e. the energy content of
a material as well as the non-renewable energy spent on its
extraction. NREU was expressed as higher heating value (HHV), also
called ‘gross calorific value’.We discuss the effect of leaving out other
potential impact categories in Section 5.3.