Abstract
The state of the art report focuses on the Heating, Ventilation and Air Conditioning (HVAC) systems energy efficiency. For planning and operational purposes the data centre infrastructure is seen in a physical perspective and subdivided in four levels: 1) Inside racks and cabinets, 2) In the data centre room(s), 3) Inside the building and li) Outside the building. At each level the technological solutions are analysed in consideration of: Components & Systems, Controls & Strategies, Emerging technologies. An important observation is that if Telenor plans to upgrade a data centre capacity to an overall heat load density of 3 kW/m2 floor area from today's reference value of 2 kW/m2 floor area. and when this would imply a heat density at rack level > 5 kW/rack, it is advisable to consider adopting liquid cooling systems. For measuring and reporting purposes the data centre is seen in a functional perspective arid subdivided into: IT services and infrastructure services. The ratio between energy use for IT services and infrastructure services gives the Power Usage Effectiveness (PUE), which is the internationally recommended metrics to measure and report overall data centre infrastructure efficiency. How to measure and report the PUE is discussed. The most important consideration for data centre infrastructure energy efficiency are summarized in a checklist