The ‘what’ and ‘how’ banana skins of upcoming H1 Energy Efficiency changes

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RANZ chief executive Graham Moor.

Chief executive Graham Moor says the Roofing Association NZ (RANZ) agrees that the thermal efficiency of our building stock must improve, but that the timing of this change needs to shift.


How appropriate as we head into winter that H1 Energy Efficiency is such a hot topic.

I attended a Zoom meeting recently with RMBA chief executive David Kelly and the MBIE about the proposed introduction date of this significant change to the nation’s buildings, both new and existing.

To be very clear, like the Registered Master Builders Association, RANZ absolutely agrees that the thermal efficiency of our building stock must improve.

However, the timing of this change needs to shift. Building Today columnist Michael Fox’s March 2022 column made the very valid point about consequences that always come with change.

Critically, there needs to be a significant educational document so that it is well understood and explained clearly. The “why” is simple. The “what” and the “how” are the banana skins here.

For our roofing industry on a new build, insulation takes place well after we have left the site. Here there is a 500mm set back from the top plate, where the R-value can be less to reduce the bulk to allow for our typical space as the rafter goes over the top plate.

However, I struggle with this, given the R stands for resistance. This 500mm band is, in part, defeating what we are setting out to do. So maybe there should be a combination of insulating products required to improve this situation?

Given the dominance of bulk products, some more thinking is required and solutions rolled out around this.

Now if we look to a typical skillion/lean-to roof, that is quite some depth required when bulk insulation is 260mm to 290mm thick.

It is critical that there is a 20mm gap between the roofing underlay and the insulation. If this is not achieved, then the roofer gets called in to explain the mould appearing on the ceiling as moisture wicks via the insulation onto the ceiling.

Likewise with metal wall cladding. As we seek to increase the R value, it is just as important that we force insulation into the framing which then bridges across the critical cavity.

I was left scratching my head with some of the official’s replies during the Zoom meeting — in particular, for us as roofers, where we retrofit insulation when
re-roofing.

I heard that if there is not sufficient room to get the R6.6 insulation, then thickness and therefore resistance can change to accommodate the room available. Sounds logical.

However, the majority of housing stock is well short on the available space, and we really need to have a better solution than fit-what-you-can.

Given the dominance of bulk insulation, we will certainly improve thermal efficiency, but we defeat some gains when the carbon footprint to transport twice the amount of insulation is factored in.

Increased cost is a given, and this just adds to the pile of increases that keep coming at us and, ultimately, our customers. Consumer confidence is tanking, and this will add to that.

There have been some that say we just need to get on with it. What about if we start from a couple of steps back first, set the scene via education and understanding, and have the solutions and answers in place.

Starting from those few steps back will enable us to eventually take the giant stride forward to more thermally-efficient buildings.

But the whole industry needs to be set to take that stride. Not just the idealists.

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