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A proposed change to how insulation settings are met is being touted as delivering savings between $2000 and $15,000 per new home build.
The change would remove a commonly used way of meeting the standards - a way the government labelled a "blunt tool" - and leave in place two more flexible ways of meeting those same standards.
The proposal originated earlier in the year as claims were being made that the efficiency settings raised in 2021 had forced up insulation costs by $40,000-$50,000.
Building Minister Chris Penk said this was what builders told him then, but this had changed.
"I've heard, however, and received official advice, that the additional costs are much less than that," Penk said on Monday.
"I don't need to be a referee on who's right in that.
"All I need to understand is that if we get maximum efficiency levels with all the benefits that are associated with good insulation practices, then we need to do that at the least possible cost."
Building Minister Chris Penk Photo: RNZ / Samuel Rillstone
The lower savings prediction from the proposed changes was still significant on, for example, an $800,000 build, Penk told RNZ.
"That's not a tiny amount ... the straw that breaks the camel's back could be $15,000."
The other change proposed would alter the ways that reaching minimum insulation 'R' standards for roofs, walls and floors could be met.
A consultation document has been issued following a review of the 2021 settings by the Ministry of Business, Innovation and Employment.
The document said the industry had told officials that a lot of investment had already gone into meeting the higher settings so "reversing them is unlikely to reduce upfront costs due to the sunk costs of these investments".
The new proposals were "commonsense changes to enable greater flexibility", Penk said on Monday in a statement.
They would add to other changes, such as allowing more building products from overseas into the country, to combat high construction inflation.
"I would love to have the cost of construction lowered and I'm confident we can get there," Penk told RNZ.
Recently, the rise in building costs had levelled off but this was due to intense competition that cut into margins.
"So even though that looks like a win to celebrate, I'd prefer that people are getting paid well for doing skilled work and that the savings are able to be made in terms of processes and products."
Penk did not have a prediction on just how much in total the combined efforts might impact on a house build's cost in a year's time, he said.
"I'm ambitious that we make it cheaper."
On insulation, parts of the industry had pushed back on initial suggestions by Penk the actual efficiency standards might be lowered, since these were raised in an attempt to make homes healthier and cut heating bill by an estimated 40 percent.
There was also debate over whether insulation was causing some homes to overheat.
The industry feedback to MBIE on that said: "Insulation does not cause overheating. Overheating is caused by poor design."
The two insulation calculation methods proposed to stay in place are the calculation and modelling methods. The ministry's review identified upfront cost savings of $3712 to $9565 using calculation and $2318 to $15,071 using modelling.
The consultation period runs till 28 February.
