In under two years, the Energy Company Obligation (ECO) and Green Deal package delivered new boilers, windows and insulation to around 830,000 extra houses, meaning warmer homes and lowers bills in time for Christmas.
Liberal Democrat Secretary of State for Energy and Climate Change Ed Davey said: "We've taken money off people's energy bills this winter, but to cut bills permanently people need energy efficient homes.
"Thanks to our ECO and Green Deal policies one million energy efficiency measures such as new boilers and insulation have now been installed in less than two years, making homes across the UK warmer and cutting household bills for this Christmas, and every Christmas."
The Liberal Democrats put the environment at the top of our agenda. Through our policies, we have ensured that homes are more energy efficient whilst keeping fuel bills to a minimum.
The 1 million milestone came a week after Lib Dems in government allocated £24 million to help over 5,000 homes receive up to £4,000 back for installing wall insulations.
In addition, a new £25 million grant announced as part of the Autumn statement will see an extra 8,000 low-income households benefit from first-time central heating off gas grid homes.