Thousands of people in Switzerland turned off their lights for five minutes on Saturday night to draw attention to climate change.
The action, which also took place in Germany and Austria, was intended to send a signal to leaders participating at the two-week international climate change conference in Bali.
The organisers in Switzerland said they were satisfied with the action, which was followed by numerous households and companies in Swiss-German regions, particular in Bern, Zurich, Winterthur, Chur and Zug.
Monika Walser, spokesperson for Swissgrid, said the lights-out action had not affected the electricity network.
European energy companies had expressed concern that once people turned the lights back on again the sudden surge would overload the power grid.
The campaign was promoted by the Blick tabloid newspaper, Google website, Pro 7 German television station and environmental organisations Greenpeace, WWF and Pro Natura.