But as participation appeared to be on the decline in recent years, supporters emphasized the goal was to raise awareness of climate change — 24 hours a day.
"Every passing year it becomes more infectious," said Ontario Environment Minister Glen Murray in a phone interview. "It's actually really doing what it intended to do, which is to get into the popular culture.
"It's not just government and environmental groups who are talking about climate awareness, but it's also companies and industries, your local pub, your local brewery."
Nova Scotia Power reported a 0.5 per cent drop in usage Saturday night as residents dimmed their lights between 8:30 and 9:30 p.m. Toronto Hydro reported a 3.5 per cent reduction, which it said was equivalent to taking 42,000 homes off the grid.
Earth Hour was launched in Australia in 2007 as a way to draw attention to environmental issues including climate change. It has grown to a worldwide event involving 162 countries.
The main organizer, the World Wildlife Fund, said more than a third of Canadians participated in Earth Hour last year.
But enthusiasm appears to have waned over the years. For example, energy savings in B.C. this year dropping to a tenth of 2013 levels.
On Saturday, residents reduced the provincial electricity load by 0.2 per cent — the equivalent of turning off about 680,000 LED light bulbs — but it's a dip from last year's one-per-cent reduction and the two-per-cent energy savings achieved a year earlier.
Murray told The Canadian Press the federal Conservatives have been "pretty disengaged" on climate change.
He said Ontario, Quebec and British Columbia are meeting timeframes for emission reductions set by the Kyoto protocol, from which the federal government has withdrawn.
"We don't want to pick a fight with the federal government, just on things like climate change they haven't been part of the conversation internationally," Murray said in a phone interview.
"It's really shifted to the provinces and the cities and the municipalities in Canada who are now taking the lead role."
Federal Environment Minister Leona Aglukkaq's office did not immediately respond to a request for comment.
David Miller, president and CEO of WWF Canada, said individuals, businesses, cities and countries are making changes to fight the most devastating impacts of climate change.
"The true impact of Earth Hour is how change is happening outside the hour, in everyday actions and decisions," he said in a statement.
"WWF is working here in Canada and around the world to ensure that change comes fast enough."
— With files from Adam Miller in Toronto and Geordon Omand in Vancouver