Energy efficiency is the use of energy with high efficiency and savings without compromising our quality of life, needs and production. It is universally recognised that the energy savings that can be achieved through the efficient use of energy are the fastest, cheapest and cleanest source of energy. Various benchmarking methods and indicators are used to determine the position of countries, sectors and companies in terms of energy efficiency. The main energy efficiency indicators used include energy intensity (TOE/1000 USD), specific energy consumption (TOE-kcal-kWh)/(m-kg-m2-m3-tonne-unit), regression analysis and sector/product-specific energy efficiency indicators. The aim of energy efficiency is to increase the efficiency of the use of energy resources and energy in order to use energy effectively, prevent waste, reduce the burden of energy costs on the economy and protect the environment. Machines that convert the chemical energy of the fuel into heat energy through combustion and transfer this heat energy to the carrier fluid are called ‘boilers’. Boilers and other combustion systems are among the most energy-intensive devices in industry and buildings. More than two-thirds of the fossil fuel energy consumed in Turkey is used in boilers, furnaces, or other combustion systems. Much of the electricity is generated by burning fossil fuels thermal power stations. However, there is considerable scope for improving the energy efficiency of boilers and combustion systems.