Fancy a life without supermarkets, fridges, flush toilets or cars?
It could happen in a sustainable Auckland, circa 2070.
Dr Ron McDowall - a senior lecturer at Auckland University's business school - believes that in 60 years, cities will support many more people with a fraction of the water and power they use today.
He has a radical vision of a world with very little waste - where today's "green"' philosophies are a thing of the past.
Dr McDowall, who spoke to the Weekend Herald ahead of this week's International Conference on Sustainability, Engineering and Science, said individual car trips would be replaced by mass transit systems until someone invented a super-efficient method of personal transport. Shops and services that required car journeys would disappear, replaced by automated services that were delivered to or near people's homes.
"Retail strips will go, banks will go. Food will arrive where you live."
By 2070, Dr McDowall expects all homes to have a food portal where the week's groceries are delivered by electric car.
"The system will help with entertaining guests, because if you want to spend the weekend at my place, your fridge tells my fridge and my fridge orders your favourite beer."
Dr McDowall said there would be dishwashers that cleaned without soap, water or energy; and clothes that either never got dirty or got clean hanging in the wardrobe.
"We cannot have nine billion people each demanding a double-drawer dishwasher that runs on power, uses water and chemicals and discharges dirty water that requires treatment," he said.
"Dishwasher manufacturers will die on their feet when someone designs a dishwasher that does not use water or chemicals."
The United Nations expects there to be 2.5 billion more people in the world by 2050. Most of the population growth will be in developing countries.
Dr McDowall, an engineer who specialises in sustainable development, said New Zealand would be left behind unless engineers started working on radical concepts like his.
"If you can tell me what [the waterless] dishwasher's going to look like, it'll be yours," he said.
Dr McDowall's future might hold some surprises for today's greenies. Seemingly green habits such as gardening and recycling would be dropped because they were wasteful.
"If you're sustainable, there's nothing to recycle because there's no waste," he said.
Today's trend towards grow-your-own vegetable gardens would seem "nuts" in the crowded cities of the future.
With so many energy savings, people would be able to survive using electricity generated from renewable sources close to their homes.
Dr McDowall said he did not know how the gadgets of the future would work.
But he has plenty of ideas, including a waterless toilet that instantly destroys waste, leaving no waste and using no contaminants.
As for industry, he said New Zealand should drop manufacturing and start designing for the mega-factories he expected would spring up around the world.
And there's one important thing he hasn't yet worked out - where we will keep the milk in 2070. He expects fridges to disappear because they use too much energy.
What our homes might look like in a sustainable future:
* Toilets will instantly destroy waste on contact, using no water or energy and leaving no residue.
* Cars will be replaced by mass transit systems.
* Dishwashers and clothes washing machines will use no water or contaminants and almost no energy.
* Supermarkets will be replaced by a portal in every home that takes delivery of the week's groceries.
* Banks will be replaced by automated banking.
* Factories will be replaced by overseas mega-factories producing goods from designs made by small teams around the world.