Division 7 Changes to installations (Article 12 and Article 2(10))

How do competent authorities decide in practice, under Article 12, whether a ‘change in operation’ may have consequences for the environment (Article 2(10)), and whether such a change is a ‘substantial change’ that ‘may have significant negative effects on human beings or the environment’ (Article 2(11))? Give reference to relevant legal provisions, guidance or procedures.