Homeowners are flooding a website assessing houses following Government legislation to improve standards.
The Green Building Council's new HomeFit site assesses how warm, safe and dry a house is.
Chief executive Andrew Eagles says the tool is environmentally aligned.
"The tool is also going to help New Zealand get to low carbon, which very important with the Zero Carbon Bill coming."
- Landlords should be banned from renting out bad homes - Greens
- Tenants 'ironically' like letting fees - landlords
- Opinion: Why renting in Auckland sucks
Mr Eagles says more than 5000 homes have been put through the online check in just three weeks.
"It shows that people are wanting to formalise and certify their homes as healthy and warm, as opposed to just a simple online check of how their homes are doing," he told Newshub.
"Some people aren't far off having a home which is healthy and warm. We had a good number that just need one or two things to improve - and with those improvements, they'd have a far better home."
Mr Eagles says the most common improvement needed is more ceiling insulation.
The Green Party welcomed the initiative when it was first announced in November.
"What the NZ Green Building Council is doing with its HomeFit initiative acknowledges the right to decent housing and it’s providing a very simple, practical tool to help that happen," said co-leader Marama Davidson.
There were more than 15,000 submissions on the Government's Zero Carbon Bill, which will commit New Zealand to being carbon-neutral by 2050.