NZ Insulation Updates
May 2023 has brought along with it a significant update for the residential insulation standards in New Zealand.
The new H1 compliance that was effective 4 August 2022 is almost completely in force. What that means for us in the lower North Island is:
The key changes
Roofs have seen a massive jump in the required insulation value, which will mean some changes in construction or methodology.
Concrete slabs on their own will no longer be deemed to comply, so edge insulation is likely to become more common. This is great as most of the heat loss in a slab is through the edge.
Windows are still required to be double glazed with thermally broken frame at a minimum, but with a higher R-value. Note, however, that PVC and timber windows far outperform aluminium thermally.
Skylights need to be of a higher quality, which makes sense as the roof is where a lot of the heat goes. Think: warm air rises!
In saying all that …
These R-values can be negotiated by carrying out what's called calculation or modelling methods. Essentially these two methods allow for some flexibility by offsetting a lower R-value in one area (say the roof), by increasing it somewhere else (the walls or windows). The calculation method somewhat takes into account the building as a whole, but it's modelling where this is done fully and for the best results. The Passive House Planning Package (PHPP) is a modelling software approved for these latest insulation changes. It has been shown over the last few decades that PHPP works to accurately predict thermal building performance not only to make sure it retains heat, but also keeps cool over the summer.
There's a small caveat...
...because while these insulation changes are a step in the right direction, they still don't go far enough. They are a blunt instrument to increase the quality without taking into account site and building specific features, which can only achieved with modelling (and is always done for passive houses).
Where to from here?
Prioritise health and wellbeing. Remember that these new R-values are only the minimum standard and that going beyond this will have positive impacts if done correctly. To that end, modelling is the sure-fire way to guarantee the building will operate correctly and that increasing insulation doesn't bring about an overheating issue. PHPP modelling is something we offer as part of our services at Reform Architecture.
For existing homes, raising the bar a little higher than the current standard is a great place to start. For some more info, check out our free resource energy efficient upgrades for existing homes where we talk some more about R-values and ways to increase your home's energy performance.
