Power consumption dropped about 2 percent on Saturday night as climate-conscious New Zealanders switched off their lights and appliances for the fifth annual Earth hour.
National power grid operator Transpower has reported "no discernible difference" in power consumption between 8.30pm and 9.30pm Saturday and the same time last year, when electricity usage fell by 2 percent.
"It's exactly the same as last year," said Kieran Devine, Transpower's general manager of system operations.
Earth Hour, sponsored by World Wide Fund for Nature (WWF), aims to raise awareness about climate change and sustainability by encouraging people to use less or no power for one hour.
New Zealand was one of the first of 134 countries expected to take part, although rain hampered some Earth Hour events across the country.
This year, WWF was asking people to think beyond the hour and make a pledge to reduce power consumption that they could sustain every day.
Earth Hour started in Sydney in 2007.
NZPA