This document specifies a maturity model addressing the environmental impact (energy management and environmental sustainability) of the facilities, infrastructures and the information and communication technology (ICT) equipment accommodated by and the and ICT software deployed in the data centre. NOTE The term environmental sustainability is used recognizing that well established treatments of sustainability feature three separate viability objectives (environmental, economic and social). For the purposes of this document, only elements of environmental viability are considered. The elements address the whole life cycle including design, procurement, operation and decommissioning.