The loan deal comes as research by the bank shows 70 per cent of those it surveyed expected to spend more time inside their house this winter than in other years.
Two-thirds of respondents said they had already noticed an increase in their power bill since New Zealand went into level 4 lockdown.
"We've all got used to spending more time at home recently and most people expect that to continue through winter. More than three out of five people told us they expect higher power bills and many of them were concerned," Silk said.
"That's why we're urging customers to think about using this interest-free loan to make their home warmer, drier and more energy efficient."
Silk said it didn't know what the take-up of the loans would be.
The loan is only available for heat pumps not other types of heating. Silk said that was because they were the most energy efficient.
She said the size of the loans would mean people could make a meaningful purchase. The bank would not be making money off the loans as they were interest-free.
Silk said if borrowers could not pay back the money within five years it would talk to them about the options.
"What we can say is it is definitely interest free for five years. At that point it may revert to part of the core home loan."
Borrowers have to use professional installers.