German ministers won backing from European Energy Commissioner Andris Piebalgs for the plans at a conference in Berlin on Friday. The proposals will be discussed at a meeting next week of Chancellor Angela Merkel's coalition cabinet.

"In future, property ads might say not just 'balcony, two rooms, quiet area' but also mention its energy efficiency," Transport, Building and Urban Affairs Minister Wolfgang Tiefensee, a Social Democrat (SPD) told reporters.

Energy certificates, giving a clear idea of how much heating and hot water costs will be, should be introduced at the end of this year, Tiefensee said, adding rules for energy efficiency in new or restored buildings would be toughened up in 2008.

The proposals form part of Germany's contribution to a non-binding proposal from the European Union to cut energy use in homes and transport by 20 percent by 2020.

Tiefensee and his party colleague, Environment Minister Sigmar Gabriel, stressed the need for Germany to be at the forefront of EU efforts to improve energy efficiency and slash greenhouse gas emissions by switching to alternative fuels.

The 27-nation bloc has already set ambitious targets for the reduction of carbon dioxide emissions from vehicles as part of its goals to reduce overall greenhouse gas emissions.

It has committed to a target of reducing EU greenhouse gas emissions by 20 percent by 2020 and offered to go to 30 percent if other nations such as the United States join in.

Conservative Economy Minister Michael Glos said the interest in renewble energy and more energy efficient products was an opportunity for Germany's small and medium-sized businesses.

Merkel's right-left coalition government has been criticised for its hypocritical approach to environmental policies, readily championing green causes but doing little to clean up industry.

While officially reconciled to a Social Democrat plan to phase out nuclear power stations, some conservatives -- including Glos -- continue to assert that atomic power is a sensible alternative to fossil fuels.

The long-running debate resurfaced at the conference on Friday, highlighting differences between the two parties as Germany attempts to draft its plans for reducing carbon dioxide emissions to meet the European Union's goals.