The Humboldt University illuminated for the 18th Festival of Lights in Berlin. File / AP

Berlin opened its annual Festival of Lights with colourful projections on key monuments on Friday, but has deployed major power-saving measures as Germany grapples with an energy crisis linked to the war in Ukraine.

The event, first held in 2005 and running until Oct.16, 2022, draws more than two million spectators to the German capital each autumn, according to organisers.

Critics had urged the private consortium behind the festival to call it off this year, saying it set a bad example while the country tries to wean itself off Russian energy with conservation measures.

But organisers said they had managed to cut their expected energy consumption by 75 per cent compared to last year, in large part by using LED bulbs and less ambitious designs, and would power the displays entirely from renewable sources.

They also switched off the lights an hour earlier, at 11:00 pm instead of midnight each night, while only illuminating 35 sites versus around 100 in past years.

"We also chose spectacles that were less energy-intensive," festival founder Birgit Zander told reporters.

Chancellor Olaf Scholz's centre-left-led government has launched a national drive to save energy amid soaring prices due to the Russian invasion of Ukraine, as the EU steps up measures to reduce power usage across the bloc.

Berlin in August began switching off spotlights illuminating some 200 buildings and historic monuments including its red-brick city hall and State Opera House as part of the country-wide effort.

Agence France-Presse