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One of the key features of the official concept design of the $715 million Macquarie Point stadium is a 'big plastic roof'.
The roof would be an Australian first, and is a non-negotiable feature for the stadium imposed by the AFL in order to give Tasmania a license for a team in the national league.
Using timber support, the ethylene tetrafluoroethylene (ETFE) roofing has been likened to a giant "backyard shade sail".
Hobart will join Munich, Beijing, Dunedin and 2024 Super Bowl host Las Vegas which all have roofed stadiums using the plastic material.
It's economical, light-weight and durable according to an engineer who specialises in rolling it out.
What is ETFE?
Martin Eddleston is the principal engineer with a construction company called Makmax Australia which specialises in 'tension membrane' materials like ETFE.
Loading...Mr Eddleston said companies like his purchased the fluoro polymer plastic on a roll and it comes like a ream of paper or carpet.
It is then transformed from a flat sheet of plastic into a 3D shape, seen on stadiums, arenas and structures around the world.
"It was developed by a couple of companies and there's only probably two or three places in the world that manufacture the performance plastic," Mr Eddleston told ABC Radio Hobart.
He said it was about a quarter of a millimetre thick and weighed less than one kilogram per square metre.
"It's incredibly lightweight," he said.
"It's one of the only things you could put on a roof this scale and get an economical structure."
How does the cushion system work?
Mr Eddleston said unlike traditional roof sheeting like metal or polycarbonate which sits on top of framing, the ETFE was tensioned using similar technology to sailing.
"The onset of this technology started from the sailing industry. It's a much more heavily engineered and scaled-up version of your backyard shade sail."
The concept design appears to show air-inflated cushions across the roof.
"So you'll have two layers of the material and a blower unit system that creates this pneumatically inflated cushion system over the roof," he said.
"That helps resist the wind load, hail load and any other applied load on the system."
He said it was easy to repair and patch, with small damage able to be repaired with a more technical version of double-sided tape and a long-term bonding adhesive.
So it's a plastic pillow structure supported with wood — how will it go in the wind?
The good news is it's not a new technology.
Mr Eddleston said the first structures using ETFE were built in the 1990s — with the method in widespread use in the US and Europe.
"We've built something like 100-150 projects worldwide, and there's 10 in Australia," he said.
"We've recently completed a project in Townsville in a cyclone zone, so it's fully designed and engineered for all the wind Australia can throw at it."
He said it was important to note the ETFE is not spanning the entire 160 metre wide roof without structure support.
The architects say it will be supported by 800mm timber and steel beams.
"That's doing the primary support job and the ETFE is really the second resistance spanning shorter distances."
How will it cope with extremes of cold and heat?
Hobart gets a range of temperatures, with winter days in the single digits and the odd day of almost 40 degrees Celsius over summer.
So whether it's a mid-winter footy match or a summer concert, the stadium and its patrons will face all conditions.
There's the promise of natural airflow for punters, with cold air brought into the bottom and hot air extracted at the top.
The architects have pointed to a stadium in Dunedin where "people sit in the sun and love it" on a cold winter's day.
But how will the plastic and timber structure cope with extremes?
"The great thing about the tension membrane class of building materials is that they are extremely stretchy," Mr Eddleston said.
"If you were to stretch the material by 2 or 3 per cent and then relax it, it would simply return to its original state."
Will I get sunburnt sitting underneath it?
The ETFE is 95 per cent transparent, and allows a broad range of the UV spectrum through so the grass can grow.
Mr Eddleston said it was possible to print the plastic with a coating similar to glazing to reduce the amount of light and UV coming through, but he said it was too early to say what the final design recommendation will be.
"Sydney Football Stadium has completely transparent ETFE over the very outer edge of the stadium to give that extra UV to the turf," he said.
"If you were under that you'd want to be wearing sun cream."
What if someone smacks a high ball?
The design has won over Cricket Tasmania and could host the world's first indoor Test match.
The roof will be 51 metres, higher than the initial 40 metres mooted in earlier plans.
Chairman and cricket legend David Boon has given it the nod, but said testing would need to occur.
According to Mr Eddleston, the short answer is a high ball would bounce back.
"It's an incredibly impact resistant material," he said.
"To be able to peg a cricket ball with much velocity at that height will be an exceptional shot," he said.
"But even so, there's been testing done by dropping bags of sand from extremely high levels and seeing what happens to the ETFE and it's a very energy absorbing material.
"There'd be no risk of it going through."
Challenge accepted.
Will it affect the sound at concerts or in rain and hail?
Some revellers have complained about the acoustics at the Forsyth Barr Stadium in Dunedin which has a ETFE roof.
But Mr Eddleston said ETFE was "pretty transparent" to sound waves.
"You will get some sound passing through," he said.
He said the cushions can have a 'little drumminess' to rain.
"But compared to other roofing types its arguably the same if not better," he said.
"In terms of sound performance, it's reasonably similar to other materials that tend to be used for stadiums and arenas."