The IEA’s Energy Efficiency Market Report 2014 estimates the worth is also growing, confirming energy efficiency position as the world’s first fuel.
IEA executive director Maria van der Hoeven said: "Energy efficiency is the invisible powerhouse in IEA countries and beyond, working behind the scenes to improve our energy security, lower our energy bills and move us closer to reaching our climate goals.
The annual report, which is in its second year, also highlights that energy efficiency investments are helping to enhance energy productivity — the amount of energy needed to produce a unit of GDP.
Over the past four decades, the energy efficiency investments have decreased more energy consumption than the total final consumption of the European Union in 2011, according to the new report.
"As energy efficiency is essential to meeting our climate goals while supporting economic growth, the increasing use of finance is a welcome development. To fully expand this market, initiatives to continue to reduce barriers will need to strengthen."
According to IEA estimates, efficiency can reduce up to $190bn in fuel costs in transport globally by 2020 and can also help ease local air pollution while addressing critical congestion issues in rapidly developing urban transport systems.
Additionally, approximately 40% of the global energy efficiency market is financed with debt and equity, marking the energy efficiency’s financial market in the range of $120bn per year.
