A renters group says the housing market is so tight people are forced to rent houses from landlords with poor records.
Renters United said often landlords found to have flouted tenancy laws are only fined a small amount, which does little to discourage bad behaviour.
The criticism follows a landlord being fined $3500 after allowing months of substandard insulation and maintenance at the property that he rented to tenants.
It was so cold a mother and her daughter shared the same bed to keep warm.
The landlord did not fix a door lock for months and failed to insulate the place properly.
Renters United spokesperson for Wellington tenants Ashok Jacob said inadequate fines are part of a broken enforcement system.
Even when a tenant knows their landlord has previously breached standards, there's not much the renter can do, he said.
"For most tenants there's no real choice as to who you have as your landlord... Even if you are aware the person you are about to sign with has had a bunch of Tenancy Tribunal orders, lots of people are not going to have that choice."
Jacob said the level of fine in the most recent case will not deter landlords from breaking the law.