Government insulation changes sensible, industry says

Tuesday, 10 December 2024

A consultation document recommending changes to the insulation regime was released on Monday.

The Government’s plans to revamp the country’s insulation regime avoid disaster as they stop short of rolling back total insulation levels, the Green Building Council says.

Building and Construction Minister Chris Penk has released a consultation document on the H1 insulation review he ordered earlier this year.

It was prompted by reports he received that new insulation standards, introduced in May last year and intended to save new homes an estimated 40% on heating, were adding significant additional costs to new build homes.

Initially, Penk asked the Ministry of Business, Innovation and Employment (MBIE) to look at the costs of rolling back the standards.

But the minister’s claims were met with alarm by much of the industry, and the Green Building Council described the minister’s plan as “unbelievably short-sighted” and “a knee-jerk reaction to a few builders’ reckons”.

Building Minister Chris Penk is proposing using different methods to work out how much insulation is needed in a home.

New Zealand Certified Builders and industry organisation EBOSS released new research showing the H1 standards added as little as $2200 to the cost of building a new home – rather than the $40,000 to $50,000 extra cited by some.

Now the industry has greeted the consultation document with relief, as rather than rolling back the standards, the main proposal is to remove the prescriptive “schedule method” used to set out insulation requirements in a new build.

Instead it proposes the use of the “calculation method” or “modelling method” to work out how much insulation is required in a particular home.

Penk said the calculation and modelling methods enable a designer to better consider the building as a whole, rather than as a series of individual components, and have been shown to reduce up-front costs as much as $15,000.

Another proposed change is to adjust the minimum ‘R-values’ (thermal resistance) for roof, wall and floor insulation, he said.

“New builds will still have to meet a certain energy efficiency standard, but designers will have more choice about how best to do this. For example, more insulation in the walls can be balanced out with less insulation underfloor.”

MBIE was also updating the data used to calculate regional requirements for insulation, and the updates should help address the issue of over warm homes in some regions, he said.

The Green Building Council’s Andrew Eagles says moving to modelling would bring New Zealand in line with most OECD countries.

Green Building Council chief executive Andrew Eagles said it was promising to see that the potentially disastrous roll back of insulation levels was not moving forward.

Keeping the standards meant people would continue to benefit from the new standards, and also ensured the country’s energy grid was more resilient, he said.

“The insulation standards were never the issue, it was how our industry was applying those standards.”

While the abandonment of the restrictive schedule method for complying with the Building Code was welcome, he was concerned that the calculation method was still on the table as part of the consultation.

“The calculation method is a step up from what many are doing now, but it’s nowhere near as effective as modelling. Moving to modelling would bring us in line with most OECD countries.

“For decades we’ve effectively been building blind – totally unaware how the insulation, glazing, ventilation, and general design of our homes will actually perform for the families that will live in them.

“Modelling helps ensure we’re creating warm, comfortable, energy efficient homes.”

The proposals show the minister has listened to the industry, Certified Builders’ Malcolm Fleming says.

Many in the industry were already modelling their house designs, including through green certification, and there was an opportunity to move to a full-modelling approach over time, Eagles said.

“We know there's strong industry and design community support for healthier, more comfortable homes, but there are challenges like cost and overheating that Minister Penk raised that need to be dealt with.”

NZ Certified Builders chief executive Malcolm Fleming said the proposed move away from the rigid scheduling method, which was a bit of a blunt instrument, was good.

He was an advocate for using a more sophisticated calculation method as it reduced the cost impact of the requirements significantly, he said.

“It gives a better overall picture of what a house needs than the scheduling method does, and now the minister’s proposals have effectively put the scheduling method in the bin.”

The minister’s announcement also suggested the view the regulations were contributing to overheating had been debunked, and that was positive as overheating was actually a design issue, Fleming said.

“The proposals show the minister has listened to industry views, and is not going to roll back the regulations that we support, so New Zealanders will still get warm, cosy new build homes.

There needs to be more and better education around the methods proposed, Master Builders’ Ankit Sharma says.

“It is a good outcome, and shows the minister has listened to industry, including the research we did with EBOSS that provided much needed hard data to inform the H1 cost discussion, and that’s encouraging.”

Master Builders chief executive Ankit Sharma said the conversation around the insulation standards and reports about costs and problems with overheating and mould had dominated the year for members.

Many of the reported problems were caused by upfront design, and rigid use of the schedule method also contributed, he said.

“The minister’s announcement is a good one, and will allow the industry to focus on delivering more affordable, healthy homes for New Zealanders.

“Adopting a more holistic building approach with good, upfront design that considers all the elements of a building together is the way to reduce costs, and issues of mould and overheating.”

But a lot of builders had been using the schedule method because they did not understand the calculation or modelling methods, so better education about those methods was needed, Sharma said.

“We’d also like to see more design guidelines from MBIE, and some more fine tuning around the climate zones to make it more suitable for different areas.”

The industry might not be prepared for the potential resource demands of appropriate modelling, Technoform’s Antony Hopper says.

Insulation manufacturer Technoform released a report last week on overheating and how to keep build costs down without reverting to old insulation standards.

It analysed five different design strategies for achieving insulation requirements while keeping costs down, and highlighted that smart design using the new standards could minimise overheating.

A contractor was meant to drill holes for insulation to be blown into a wall space, but a camera suggests he didn’t. That was confirmed by a thermal imaging camera.

Technoform national sales manager Antony Hopper said the company supported the intention of the changes proposed by the minister and MBIE.

The highlight was the removal of the schedule method for glazing, and the reduction of “plug loads” in the verification method as it more accurately reflected the energy required to heat a home, he said.

“But there are several areas of concern. One example is that the calculation method fails to account for solar heat gain from glazing.

“Others include that the reduction of the wall R value [the wall’s thermal resistance] based on poorly designed walls sets a problematic baseline, and promotes suboptimal framing design.

“And the solar heat gain coefficient is incorrectly defined as being the same as the glazing g-value [total solar energy transmittance], which it is not, and could lead to underestimating the amount of radiant heat that can enter the building.”

Additionally, the industry might not be adequately prepared for the potential resource demands required to conduct the necessary modelling, Hopper said.