Since 2015, improvements in global energy intensity have been weakening each year. Energy Efficiency 2019 examines the reasons for this slowdown, which has major implications for consumers, businesses, governments and the environment. The rate at which energy-using technologies are becoming more efficient is slackening, and at the same time societal changes are adding to energy demand faster than technological change can keep up. On top of this, progress on policy and investment remains flat. In addition to tracking trends in energy efficiency policy, investment, and technology, this year’s report highlights how the digitalisation of our homes, businesses and transport systems provides immense opportunities to improve energy efficiency in systems and end uses. However, policy makers must engage with a range of challenging issues if the world is to harness digitalisation for greater energy efficiency. The IEA explores these with its new Readiness for Digital Energy Efficiency policy framework, presented in this report for the first time. Energy Efficiency 2019 is the authoritative tracker of global energy efficiency trends, providing policy makers and others in the energy sector with crucial insights into the status of global energy efficiency.