Improvements in air conditioning control strategies and systems cut consumption of natural gas and electricity.
Other contributors were increased recycling by the public and staff, improved power-saving by staff and more use of energy efficient LED lighting.
Mr Brown saw cutting carbon as a crucial environmental goal on the path toward making Auckland the world's "most liveable city". "I would encourage other Auckland organisations, whether they be public or private, to consider whether the museum's sustainability innovations and learnings could be applied to their businesses."
Museum director Roy Clare saw the reduction as an "essential contribution to the global green agenda for change".
"Aucklanders and the tourists who visit the museum increasingly expect us to make continual improvements to our environmental performance.
"Our goal is to lead the way, set the standard for others and contribute to the success of Auckland Council's environmental and tourism strategies."
Since 2010 the museum had produced efficiencies by changing its emissions mix.
In 2010, electricity was responsible for 45 per cent of emissions, natural gas 42 per cent and travel and waste 13 per cent.
Last year, electricity was raised to 55 per cent of emissions, gas reduced to 31 per cent and travel and waste was roughly the same at 14 per cent.
Natural gas was consumed to produce high temperatures for the museum's air conditioning and ventilation systems, with electricity used to produce low temperatures, lighting and for general purposes.
This brought down its projected 2013 electricity bill from $798,000 to $559,000 and natural gas from $182,000 to $81,000.
