there are elements of subjectivity in the definition of the
system’s boundaries and in the individualization of the data
sources;
the data necessary for the study are not always easily accessible,
which influences the reliability of the data and the quality
of the obtained results [18,41];
the research conducted only considers aspects of GHG emissions,
omitting other environmental aspects and those
economical and social aspects that can be connected to the
object of the study.