But poor project participation among landlords has renewed calls for a "housing warrant of fitness" from health and community advocates.
So far, only 28,000 homes insulated through the project have been rentals, according to the Citizens Advice Bureau (CAB).
Mr Martin said many residents were hesitant to approach landlords about insulation, fearing they could "kick them out".
"Sometimes there's six people wanting the same house in Rotorua.
"They often just live as is," he said.
Under the project, 33 per cent of ceiling and floor insulation costs - up to $1300 - was provided to owners whose homes were built before 2000.
Community service cardholders and landlords with tenants who were community service cardholders qualified for 60 per cent of funding towards insulation.
Dr Andrew Hubbard, CAB national research and policy adviser, said too many Kiwis fell ill due to cold, damp or mouldy living conditions.
Those who suffered the most were families with babies or small children, he said.
"We need to urgently implement minimum standards for heating, insulation and weather tightness to ensure a decent standard of housing for all New Zealanders."
A group on child poverty, appointed by Children's Commissioner Dr Russell Wills, has also advocated a housing warrant of fitness scheme.
Research showed high rates of poverty-related child illnesses such as respiratory-related infections could be reduced by making houses drier and warmer.
But property investors have warned such a scheme could result in higher rents.
Andrew King, president of the New Zealand Property Investors Federation, said many landlords found the Government's subsidised insulation scheme too expensive.
For example, a standard three-bedroom house would cost about $3000 to insulate through the Heat Smart scheme, after the $1300 subsidy, he said. Landlords could do it themselves for about half the price, Mr King said.
"The [housing] warrant of fitness is definitely going to increase rents and we just don't believe it's in the best interest of the tenants."
Regulation around insulation and heating would be a better alternative, he suggested.
However, tenants must understand costs associated with rental properties would eventually be reflected in rent, Mr King said.
Nationally, a further 230,000 homes are expected to receive insulation as part of the Heat Smart project before it finishes in September.