Mark Thomson, the airport's general manager of property, said the parties involved were conscious of the need to act in the interests of shareholders.
"The transaction was completely transparent," said Thomson, who started in April, well after the sculpture park was set up.
"The reason the issue was flagged to me, and I made some inquiries about it, was because the sculpture park was up for an award," he said, referring to the NZ Property Council's annual event where prize-winners were announced this month.
The sculptures are set around a stormwater catchment lake to the left of George Bolt Memorial Drive, as people enter the airport precinct.
Thomson said the sculpture park was part of the airport's "place-making initiative", which has also seen the creation of the new events centre Abbeville Estate, development of a football field and a terraced, landscaped area near the sculpture park.
The airport company commissioned 10 sculptures for the park.
More art installations are being placed in other airport areas such as the terminal entry roundabout and in the Landing precinct.