Integration of the management of energy and environmental systems was suggested by the scholarly literature in the early phase of
dissemination of ISO 14001, as a potential way to improve the environmental performance of companies. Nevertheless, there has
been little empirical work reported in the literature that explores this proposition in depth, or sheds light on relevant issues such as
the additional effect of an Energy Management System when an Environmental Management Systems has previously been adopted.
This lack of research is now even more evident as the adoption of Energy Management Systems is gaining momentum after the
launch of ISO 50001 in 2011, following the example set by ISO 14001. The present work aims to shed light on these issues based
on an in depth, empirical, exploratory study carried out in eight Spanish organizations. The findings make it possible to anticipate
the benefits and potential pitfalls of the adoption of Energy Management Systems in companies that already have environmental
certification.