The analysis found there were not enough council-owned houses to cope with that growth in demand, and that it was unlikely there would be enough private rentals to pick up the slack.
If neither sector could grow its stock with demand, Tauranga's elderly might be stuck in overcrowded, substandard accommodation - or forced to move further out of the city.
The council, which has been considering what to do with its portfolio of 246 pensioner housing units, asked independent group The Housing Foundation to review the future demand and need for elder housing in Tauranga.
The foundation's recommendation - that the council sell its portfolio to a community housing provider - will be considered at a meeting of the council's Community and Culture Committee meeting today.
A second option - the council retains ownership but forms a leasing or partnering agreement with a community housing provider - will also be considered.
Neither option makes building or buying extra housing stock a requirement. The first would ask the new owner to "where feasible, increase the supply of elder housing".
The second option could result in less housing, suggesting the council could sell some of the higher-valued villages needing redevelopment and use the money to buy land and build new properties somewhere else.
"Although reducing the supply when there's a growing demand might make it more expensive to meet elder housing needs in the future," analysts warned.
Tauranga social scientist Carole Gordon, a gereology specialist, said looking at ways to increase the supply of accessible, well located, warm homes for older people should be part of the discussion the council was having around its pensioner villages.
That the population of older people in Tauranga was increasing was not new information, she said.
"The issue is that the demographics are known and we need to be more focused on catering to the needs of older people.
"The council can help that process by being more proactive with its age-friendly city programme.
"Now it is time to get on with the planning for the increasing number of older people in our community."
She wanted to see the council welcome the wider community into its discussions and deliberations on the issue of affordable housing for older people.
"It is in all of our interests that vulnerable older people are looked after in our society."
Tauranga and Western Bay Greypower president Jennifer Custins said the council's analysis of that a projected elder housing crisis was looming not new, as it something that was forecast some four or five years ago. She was open to any solution that would benefit older renters, she said.
Mrs Custins said if the council decided to sell of its pensioner housing to a social housing provider, she hoped the new organisation's goal was not only to upgrade the existing stock but significantly add to its portfolio of rental properties.
Tauranga Mayor Greg Brownless said increasing the amount of social housing should be the responsibity of taxpayers not ratepayers as it would be an "impossible burden" to expect ratepayers to do so.
Mr Brownless said he was not adverse to the council retaining its existing pensioner housing stock but the big question which needed to be answered was who was going to fit the bill to cover ongoing maintenance costs.
If the council decided to sell off its pensioner housing stock to a private social housing provider or to a private trust those parties would have access to government subsidies whereas councils do not, he said.
Housing struggling older people in Tauranga
- 246 elder housing units in nine villages in Tauranga and Mount Maunganui
- 125 of those units will need replacing by 2025
- Total replacement cost estimated at $15m using 2017 pricing
- Older rental housing need projected to increase 81 per cent from 2120 to 3830 households by 2028
- Needy older rental housing will increase from 4.2 per cent of all households to 6.4 per cent
