Mr Little said there was no point in having an insulated house if it was not heated properly.
If his bill passed into law, landlords would have to upgrade underfloor and ceiling insulation to 2008 standards within five years for existing leases, or within a year for new leases.
The changes in Mr Little's bill would increase rents by an estimated $6 a week if the costs were spread over 20 years, the Labour Party estimated.
That estimate was based on costs for landlords of $3300 for retrofitting insulation, $2500 for installing a heatpump, and $500 for fixing draught and ventilation problems.
Housing Minister Nick Smith said Mr Little's bill was "too little and too late".
Some rentals would not be upgraded for five years under Labour's plan, he said, compared to three years under National's proposals.
Dr Smith said there was only a 5 per cent different in heat loss between the 2001 and 2008 standards, and it did not make economic sense to force all landlords to upgrade to the higher standard.
The Government estimated that its own proposed changes would raise rents by $3.20 if spread over 20 years.