Environmentalists say more than half the nation's adults took part in Earth Hour earlier this year, switching off lights and other non-essential appliances.
According to national figures sourced from Transpower, there was a national energy saving of 3.5 percent, and the West Coast saved 8 percent for the hour.
Estimated savings in other regions included: Northland 1 percent, Auckland 3 percent, Waikato 3 percent, Bay of Plenty nil, Hawke's Bay 3 percent, Central North Island 7 percent, Taranaki 5 percent, Wellington 3 percent, Nelson-Marlborough 6 percent, Canterbury 6 percent, South Canterbury 1 percent, Otago-Southland 2 percent.
The effort by 1.5 million people was "an amazing commitment by so many New Zealanders sharing hope for the future and commitment to the planet," said WWF-New Zealand executive director Chris Howe.
He said a survey found 51 percent of New Zealanders older than 18 participated in the March 28 switch-off, which covered 44 cities, towns and districts ranging in population from Auckland to the 800 people on the Chatham Islands.
Hundreds of millions of people in more than 4000 towns and cities around the globe participated at different times through the day.
"Earth Hour showed that Kiwis care about climate change and are taking voluntary action to respond," Mr Howe said.
The survey reported 57 percent of the people who switched off lights said it inspired them to do something else to reduce their impact on the environment.
A similar Australian survey showed almost half the populationparticipated.
WWF and Earth Hour supporters in Wellington were today due to present the survey results to Environment Minister Nick Smith.
Mr Howe said the results were being released as global talks on climate change started in Bonn this week.
WWF has called for governments around the world to agree to cut global greenhouse gas emissions to 80 percent of 1990 levels before the year 2050.
The target it said was needed to prevent global temperatures rising more than 2degC this century.
Even a 2degC temperature rise is expected to subject up to two billion people to water shortages and threaten extinction for over 20 percent of the world's species, according to a 2007 United Nations report.
The New Zealand switch-off was partly driven by the involvement of some local councils, according to WWF.
"Some didn't take part in this campaign because they didn't feel a symbolic action would make a difference," Mr Howe said.
But a recent government survey showed 53 percent of citizens said they personally worried about climate change, and 87 percent supported government incentives for households to improve energy efficiency.
