This document: a) describes the general principles for data centres upon which the requirements of the EN 50600 series are based; b) defines the common aspects of data centres including terminology, parameters and reference models (functional elements and their accommodation) addressing both the size and complexity of their intended purpose; c) describes general aspects of the facilities and infrastructures required to support data centres; d) specifies a classification system, based upon the key criteria of availability , security and resource and energy efficiency enablement over the planned lifetime of the data centre, for the provision of effective facilities and infrastructure; e) details the issues to be addressed in a business risk and operating cost analysis enabling application of the classification of the data centre; f) provides reference to documentation, operation and management of data centres; g) introduces the concepts of Key Performance Indicators (KPIs) for resource management and resilience of data centre facilities and infrastructures; h) defines the use of an environmental sustainability strategy. The following topics are outside of the scope of this series of documents: 1) the selection of information technology and network telecommunications equipment, software and associated configuration issues are outside the scope of this document; 2) quantitative analysis of overall service availability resulting from multi-site data centres; 3) safety and electromagnetic compatibility (EMC) requirements (covered by other standards and regulations. However, information given in this document can be of assistance in meeting these standards and regulations).