Landlords can now be fined if their properties fail to meet Healthy Homes standards within 90 days of a tenancy starting, after a new law came into effect on July 1.
But tenants say landlords shouldn't be left to enforce the rules.
The Healthy Homes standards require rentals to have heating, insulation, ventilation, proper drainage, and for unreasonable gaps to be closed. From July 1, landlords have 90 days to comply from the time a tenancy starts or is renewed.
"We are hoping that landlords are taking the initiative here," Prime Minister Jacinda Ardern said on Thursday.
But it's up to landlords to conduct the Healthy Homes assessment. If tenants disagree with the assessment, they can take it up with the Tenancy Tribunal.
Housing Associate Minister Poto Williams says if tenants find landlords aren't being compliant, the opportunity to go to the tribunal is always there.
But Robert Whitaker from Renters United says the Government is relying on tenants enforcing the law on their behalf - and he warns that comes with a risk.
"The risk is, of course, that the relationship will break down afterwards; that the landlord and the tenant will no longer get on to the extent the tenancy can continue," he explained.
Landlords could take a hit too; if they don't meet their obligations by the 90-day deadline, they could face damages of up to $7200.
"We think that's a pretty good incentive if you're a landlord to meet the requirements at the right time," says Real Estate Institute of New Zealand spokesperson Dee Crooks.
Renters United is calling for independent assessors to be brought in, but Williams says there's "a cost factor involved in that".
The Prime Minister wouldn't be drawn on it.
"By setting standards we are trying to make sure that we're creating an understanding broadly about what needs to be done," she said.
Standards set to make homes warmer could get heated instead.