Liquid Cooling in Data Centres maps liquid cooling technologies, and analyses challenges and opportunities in implementation and the impact that liquid cooling can have on data centre energy efficiency. The report indicates energy savings potentials in the region of 8% in servers and 30-40% at the facility level translating to overall savings in the order of 10-21%. Current use of liquid cooling in data centres is low due to lack of standardisation, high initial costs and concerns about long-term reliability. A further barrier is that the metric Power Usage Effectiveness systematically understates the efficiency gains from liquid cooling. The report makes a case for policy intervention and highlights the need for new solutions for retrofitting existing multistorey data centres.