Children's commissioner Dr Russell Wills says a bill intended to bring rental properties up to standard is weak, and will do little to prevent children living in cold, damp housing.

A bill intended to prevent children from living in poor quality rental houses is a "shameful" broken promise by the Government, says the Children's Commissioner.

Russell Wills is expected to deliver a scathing submission to Parliament's Social Services Committee on Wednesday, when it sits to hear opinions on its Residential Tenancies Amendment Bill.

The bill would require landlords to install smoke alarms and insulate properties to current standards, if those homes weren't already insulated to 1978 standards.

Supplied Auckland toddler Emma-Lita Bourne, died from causes attributable to her families cold and damp Housing NZ rental property, a coroner found last year.

Homes which were already insulated to 1978 standards would not be required to be further insulated.

Housing Minister Nick Smith announced the changes midway through last year, a month after Auckland toddler Emma-Lita Bourne died from a brain haemorrhage.

A coroner said the poor condition of the state house in the South Auckland suburb of Otara was a contributing factor to Emma-Lita's death.

Smith described the update as "the biggest improvement in the quality of New Zealand's older homes this decade than in any decade and it will see a half million New Zealanders, particularly those on low incomes, having a safer warmer and drier homes".

Wills has described the bill as "shameful".

"It is intolerable that we have 42,000 admissions and 15 deaths a year for children with conditions associated with poor housing and poverty. This bill will do little to change this," he said.

"When the 2013 Budget came out suggesting trial of a WoF for private and state housing, Government made a promise to New Zealand children: We will make your house healthy.

"Three years on from that Budget promise, this bill will do little for children living in cold, damp, mouldy housing. It is a wasted opportunity and a broken promise to our children."

Wills said the onus should be on landlord to get their properties to a liveable condition, and councils should proactively inspect them.

"Tenants still have to complain if they believe the house is not up to standard. All our experience shows that they don't and won't complain because they're too scared they'll lose their house or be unable to rent anywhere else".

Unicef is also expected to submit on the bill. In it's draft submission, it said it supported the introduction of the bill but agreed there needed to be improvements in the enforcement of the law and regulations.

"A full warrant of fitness scheme would provide for inspections of dwellings. Since there is no full warrant of fitness in the bill, enforcement of the standards will rely on disclosure in tenancy agreements and complaints by tenants.

"Inspections would be a more powerful way to ensure standards are being met," Unicef said in it's submission.

Wills said there was also no heating or ventilation standard in the bill.

"Children will therefore continue to live in cold, damp, mouldy, private rental houses. They will continue to be admitted to hospital with the same conditions and some will die. This is shameful," he said.

The legislation sent a message to children that they were "not important enough for us to set a standard for heating for your house and to check to make sure your house is healthy".

Wills said he would be asking the Government, during his submission, to include a requirement that all houses meet current insulation standards, that a heating and ventilation standard be applied and that monitoring or enforcement of standards by local councils be legislated for.

"Surely our children deserve more than this."

This evening, Smith said he was disappointed with Wills' claims the Government did not care about children.

"I just totally reject that, and I'm disappointed that the Commissioner is claiming a monopoly on wisdom."

Smith said housing warrant of fitnesses were an expensive option that would harm the very people the Government was trying to help.

"The Government's view is that we have a small number of bad-apple slum landlords, and that rather than a Warrant of Fitness over 500,000 homes, we're better to have a targeted approach that goes after those homes that are of poor standard."

He said enforcement measures in the bill would allow the Housing NZ to directly prosecute bad landlords, who moved to quit tenancies rather than address complaints.