Dr Kay Saville-Smith, a principal investigator with the challenge, says two decades ago, more than 80 per cent of people aged 65-89 owned a home. By 2013, that had dropped to 60 per cent.
"In the past we knew what would happen to older people. They would be homeowners and they would be mortgage free and their living standard was really quite high given their low incomes," she says. "But the future is going to be very, very different."
Saville-Smith says elderly renters are particularly vulnerable to tenancies being terminated, and rent hikes. "Older people can't increase their incomes very easily if at all, so they're some of the people who get really squeezed in an overheated market."
She's also concerned about their welfare. Her researchers have heard stories of pensioners sitting in the dark because they're unable to reach the lightbulb to change it. Some are too scared of upsetting the landlord to ask for things to be fixed it they break. They're also more likely to be in a home which is damp and cold.
More starkly, those renting suffer from worse health than those in their own homes. Rates of illnesses including asthma, anxiety and depression are twice as likely among elderly renters.
"If we don't change things, it's a very bad outlook, which will mean higher degrees of insecurity ... increasingly dilapidated housing ... and a lot more elderly people literally homeless" Saville-Smith says.
She says superannuation at current levels won't be enough. "It's designed to give older people a good standard of living, but it assumes they're not going to be paying mortgages and not going to be paying rent."
John Hurrell, 74, volunteers with the Salvation Army packing food parcels for people who are struggling to get by. He's seeing many people's savings run out in their mid-seventies - and he's worried he's going to be one of them. After losing his business, and his home, in the global financial crisis, he's now renting.
"Because of health reasons I've had to stop working. So I'm faced now with trying to live on super in a rental market that's actually going up in terms of cost," he says.
He believes the only way to ensure the elderly are properly looked after is for the Government to bring back pensioner housing.
"This tsunami is just starting. I'm the beginning of the baby boomers and there's a big crowd behind me," he says.
Saville-Smith is heartened that the Government is moving to regulate the rental market, but she wants to see more focus on supporting the elderly. She'd like to see the building industry incentivised to construct smaller homes to meet demand, and she thinks models like Abbeyfield's shared housing model could become more widespread.
The Abbeyfield flatmates think many more elderly people could benefit from living like them, not just financially, but socially too.
Norma Gordon-Kerr has just moved in, after renting alone.
"My health went downhill and I got quite lonely because I couldn't get out enough," she says.
Over lunch made by the in-house cook, she says she feels right at home. "I know I'm amongst friends now and I really enjoy it."
- Aotearoa Science Agency