Energy managers say $2 billion a year could be saved by New Zealand businesses by using well-established energy savings techniques.
The Energy Management Association is an umbrella group for about 340 energy engineers who work to make commercial and industrial buildings more energy-efficient.
Improvements it suggests include automatic switching that turns off machinery at night and regular maintenance to make sure equipment is operating efficiently.
The association says not many other costs can be minimised so easily.
But it says many business leaders seem reluctant to adopt these measures because there is the perception that energy costs are fixed.
Savings would equal the the entire electricity usage of a town like Napier, the association says.