Eleven giant heat pumps, each about 100 times bigger than their regular household cousins, have been installed at Auckland Airport.
The airport said the $15 million project aimed to make it less dependent on natural gas.
The machines are for the international terminal, which got hotter when crowded and cooler when fewer people were around.
The airport said the collection of 600kW heat pumps should reduce fossil fuel use for heating and cooling the terminal by about 40%.
Auckland Airport’s previous gas-fired air-conditioning system at the 141,000sq m terminal had been running for half a century.
Martin Butcher, project lead engineer, said an earlier trial showed how the system responded to Auckland’s volatile weather and fluctuating passenger volumes.
“For the main system replacement, we transitioned the changeover in carefully planned stages, which allowed us to confirm how the system performed while keeping the terminal operating normally for travellers.”
He said the building acted like a thermal buffer.
“Temperatures shift slowly, which gives the system time to respond without creating noticeable temperature swings for people in the terminal.”
The new pumps could run in “mixed mode” – heating one area while cooling another – and reuse waste heat, improving efficiency during busy travel times.
Ellie Callard, Auckland Airport sustainability manager, said spaces could cool down quickly when the terminal wasn’t busy.
“Passengers move through the terminal in quite big groups, which has a really big impact on how we heat and cool the terminal.”
Mary-Liz Tuck, the airport’s chief strategic planning officer, said the project used cranes to install the 12-tonne heat pumps on to the roof.
“This project marks an important step in how we’re modernising the airport’s core infrastructure while materially reducing the emissions within our control.”
She said the new system provided efficient, low-emission climate control across the terminal, from check-in and departures through to airside and biosecurity areas.
Tuck said the airline aimed to cut Scope 1 and Scope 2 emissions by 90% by 2030, compared with a 2019 baseline.
Scope 1 emissions are direct greenhouse emissions from sources an organisation controlled or owned, such as pool cars.
Scope 2 emissions are indirect emissions associated with buying energy.
“The decarbonisation pathway for the aviation sector is not straightforward, with no single solution, but actions such as switching our terminal heating and cooling from gas to electric are steps we can take today,” Tuck said.
In the most recent financial year, natural gas made up 29% of Auckland Airport’s direct emissions, largely from energy for heating the international terminal.
The new system was now in what the airport called a fine-tuning phase.
“Commissioning will continue through to next winter to validate year-round performance,” the airport added.
The airport said it was also investing in renewable energy generation, aimed at cutting how much it took from the national grid.
Hydroelectricity provided the biggest share of generation in New Zealand, generating 2865MW with capacity of 5415MW, according to grid operator Transpower.
Gas, coal, oil and diesel had capacity of 2186MW.
The airport said it had also installed rooftop solar arrays on the Transport Hub and Mānawa Bay, capable of generating 3.5MW of clean energy.
Other significant projects at the airport include a temporary check-in pavilion next to the international terminal, due to open in the next few months.
Then the departures hall will get an upgrade.
International and domestic jet travellers will eventually mingle at a new integrated terminal set to open in 2028-29.
And before the new domestic jet terminal opens, the airport will build a new secondary runway.