A $2.7 million shade structure in Darwin’s CBD has been found to have reduced temperatures by less than 1℃. 

The 55-metre structure on Cavenagh Street was built as part of an NT Government plan to turn Darwin into “a cool, tropical, world-renowned destination”. It was an ambitious plan for a city where some surfaces hit temperatures between 45℃ and 67℃.

In 2018, Chief Minister Michael Gunner said Cavenagh Street is a “a river of fire” that needs a reduction of between 2℃ and 4℃ to make Darwin “walkable and liveable”.

The shade structure was meant to have been overgrown with tropical vines to enhance its cooling effect, but in the two years since it was built, those vines have not grown as intended. 

The Government spent $80,000 evaluating the structure's “cooling performance”, and that report has been obtained by the ABC through a Freedom of Information request.

It reportedly shows the structure decreased average temperatures by about 0.4℃ in its first year, and about 0.7℃ in the following year (to July 2020). Relative humidity under the shade structure appears to have increased. 

“It is believed that when the shading is fully covered results will be different,” the report allegedly states.

Still, the NT’s Infrastructure Minister thinks it is a great idea.

“[I] absolutely love that shade structure,” Ms Lawler said last week.

“I, like anybody, would have hoped that those vines grew very, very quickly.

“I would have done everything in my power to make sure they grew quickly but the reality is they will continue to grow.”

The Department of Infrastructure, Planning and Logistics has issued a statement saying it does not know when the vines will fully cover the structure.

“The Cavenagh Street shade structure and landscaping was constructed as a trial project to contribute to reducing the ambient temperature in the Darwin CBD by up to 2 degrees and improving thermal comfort ['feels like' temperature] for pedestrians,” it said.

“While early analysis indicates a reduction of temperature under the structure, as well as in its immediate vicinity, the full effect of the structure, like any trial, will take a number of years.”

The researchers behind the review have won approval to extend their evaluation from the  original deadline in March to December this year.