The supply of heat is largely ignored in the energy and climate change debate, even though heat represents nearly half the world’s final energy consumption (meaning energy that is supplied to the consumer for all final energy uses such as heating, cooling and lighting). In 2009, heat represented 47% of final energy consumption, compared with 17% for electricity, 27% transport; and 9% for ‘non-energy use’ (which covers fuels that are used as raw materials in different sectors, such as oil used to make plastics). Oil, coal and gas account for more than two-thirds of the fuels used in meeting this significant demand for heat. Because heat represents such a significant share of the world’s final energy consumption, the IEA stresses the importance of examining opportunities for decarbonising the heat sector. Such opportunities can be found in the implementation of energy efficiency measures (such as reducing heat demand in the building sector by implementing minimum energy performance requirements), co-generation of electricity and heat in the energy sector, or by replacing fossil fuels with renewable energy sources.