Europe have slashed their energy consumption targets six years ahead of time, cutting greenhouse gas emissions by the equivalent of switching off around 400 power stations.
In 2014, the EU's 28 member states consumed 72 million tonnes of oil equivalent, which is less than had been projected for 2020, according to a report published by the Joint Research Centre (JRC).
Environmental campaigners described the achievement as "remarkable" and "incredible" but the European Commission were restrained.
A spokeswoman for the Commission said: "Final energy consumption is currently below the 2020 target. The EU are also on a good pathway to achieving the primary energy consumption target for 2020 if current efforts are maintained."
Major energy savings were reported across all sectors in the study, with EU legislation driving efficiency gains in electrical products, industry installations, fuel economy and the housing sector.
Energy use in residential buildings fell by 9.5% between 2000 and 2014, second only to the industrial sector, where there was an energy drop of 17.6% over the same period.
However, energy analysts are concerned that the UK Government could move in the opposite direction once no longer bound by EU legislation.
Ingrid Holmes, director of the E3G thinktank in London, has said: "Brexit creates enormous uncertainty over how the UK will continue to provide affordable and secure energy to its people. Energy efficiency works, and its time the Government committed to at least match the ambition of energy saving actions taken by the rest of Europe."
The secretary general of EuroAce, Adrian Joyce, has said: "The building sector made a massive contribution to this achievement, particularly in residential buildings, which politicians see as the toughest part to reach. People might find it incredible that we reached our energy use target ahead of the deadline but it is a demonstration of what good EU policy can achieve."
The EU has set a 27% efficiency goal for 2030, and could potentially increase it next month when the Commission brings forward a raft of efficiency measures. The focus will be on updating buildings and efficiency Directives, with an outside chance that the eco-design plan could also be published.
However, euro sceptics and environmentalists may at least be united in pointing to the JRC report’s cautioning that financial crisis played a part in several countries’ reductions in energy use. "It has contributed to get energy consumption back on track towards the EU energy and environmental targets for 2020," the study said.
Pieter de Pous, policy director at the European Environment Bureau, said: "We need a real decoupling of energy use from economic growth or the moment the economy picks up, we will be back to square one."
