Re-roofing highlights H1 limitations

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RANZ chief executive Graham Moor.

Roofing Association NZ (RANZ) chief executive Graham Moor is happy that H1 Energy Efficiency changes have been delayed, but says re-roofing an existing house highlights their limitations.


I was very pleased to see the prudent six-month delay of the H1 Energy Efficiency changes.

The changes for new wall, floor, and roof insulation performance requirements for new homes are to be introduced on May 1, 2023.

For the majority of Master Builders building our new homes, it will get sorted — we will all lift our understanding levels to match the H1 changes via education, and we will be ready.

However, the H1 changes also have significant implications not only for building new homes, but for re-roofing work. How so, you may ask?

Frequently when re-roofing, we fit new insulation when space in many existing roof cavities doesn’t allow us to use a 290mm-thick bulk insulation, as required with the incoming changes.

RANZ discussed this with the MBIE, and the response was along the lines of, if you can’t get it to fit then it’s okay to put back a newer version of what’s there.

Will that achieve what the changes intended though? Considering that the changes to H1 are to improve energy efficiency which will result in better health outcomes for the occupants, if we just put back what was there then will we improve health outcomes?

Any changes should be made to improve new and existing building stock. There is no doubt that they will achieve better results for our new housing stock, which will number around 35,000 to 40,000 houses a year.

Our existing housing stock numbers around 1.9 million though, and if just 5% of those houses were re-roofed and re-insulated that’s 95,000 houses.

Not all of those will have restrictive roof spaces, but you get the picture — it’s a significant pipeline.

There will be thousands of homes where thermal efficiency, and the health of the occupants, will not be improved very much at all by these changes.

Then there will be some who will force bulk insulation into a space it won’t fit. That will cause other problems.

As a sector, it seems like we are the victim of an attitude which holds back the performance of our built product. What we generally do is just enough to comply.

With our performance-based Building Code, we get what we get, dependent on the settings — few do much more than what the code requires.

If we really want to improve our housing stock and the way it performs, then surely going well above compliance is called for and, in turn, helping to future-proof our housing stock as well.

To do so, we need to think it through on that longer time scale, and ask ourselves what performance requirement implemented in 2022 will still be holding in 2072?

Some of you will be thinking that building to that performance level adds a lot of cost.

I know you have a consumer that changes their home about every seven years, and they may well be questioning why they should pay for something now that they won’t benefit from.

But that is a misconception — they do benefit from it. Building more value for the life of a dwelling is not accurately measured in upfront costs — the benefits to human health, longevity of a building, and sustainability are all majorly beneficial.

However, the upfront costs are apparent for increasingly cash-strapped consumers to be burdened with.

For example, estimates on additional per-build costs incurred by the H1 changes have been cited as $15,000 to $40,000.

What if the average home was reduced in size by, say, 10sq m? Would that cover the additional cost of these H1 changes?

Perhaps what is needed is more focus on consumer education, coupled with proposing viable solutions to those consumers.

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