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NZ Building Code · Energy & H1H1/AS1 6th Edition: what actually changed
A plain-English rundown of NZBC clause H1 Energy Efficiency and the H1/AS1 6th edition — the compliance methods, what changed, and how it plays out on a typical new build.
NZBC clause H1 Energy Efficiency is about keeping the heat you pay for inside the building. The Acceptable Solution H1/AS1 covers the housing thermal envelope — roof, walls, floor/slab and windows — and the 6th edition is the version in force now.
Which edition applies
The 6th edition was published on 27 November 2025 and is in force now. The previous 5th edition Amendment 1 stays valid for consents lodged up to 26 November 2026, so both are around during the transition.
The three compliance methods
H1/AS1 gives you paths to show your building meets the energy-efficiency requirement. Under the 6th edition there are two live options, because one of the old paths is gone.
- Schedule method — REMOVED in the 6th edition. This was the simple “just hit these R-values element-by-element” path for small, simple buildings. It’s gone, because it didn’t account well for thermal bridging.
- Calculation method — the everyday path now. You total the heat loss of the whole envelope and show it’s no worse than a reference building. Trade-offs are allowed — more glazing if the walls or roof do more.
- Modelling method. A full energy/thermal simulation, used for complex or high-glazing designs.
What changed in the 6th edition
The performance bar itself didn’t move — the big R-value step-up landed in the 5th edition, and the 6th mostly revised the methods. The main changes:
- The Schedule method was removed — it’s Calculation or Modelling only.
- Multi-unit dwellings may be treated as a single or multiple thermal envelopes.
- Better thermal-bridging accounting, plus new tables for windows and slab-on-ground.
- The NZS 4214 citation was tidied for clarity.
How it plays out in practice
For a typical new build, the BRANZ House Insulation Guide spreadsheet runs the Calculation method for you. The flow is straightforward:
- Enter the stud size and spacing.
- Enter the insulation R-value.
- Read back the construction R-value it returns.
- Check that construction R-value against the target.
Plain-English guide, not advice. This page helps you understand and navigate the rules — it is general information, not design, engineering or consent advice, and it does not reproduce the copyrighted tables of NZS 3604 or any Standard. Always check the current Standard or Acceptable Solution and your BCA, and use a suitably qualified LBP, engineer or QS where it matters.
Do it in Toolie
Put this into practice with the H1 R-value calculator · the insulation calculator · H1 6th edition. Try Toolie free — no signup — or open this topic in the Toolie app.
Common questions
Is the H1/AS1 6th edition in force yet?
Yes. The 6th edition was published on 27 November 2025 and is in force now. The previous 5th edition Amendment 1 stays valid for consents lodged up to 26 November 2026, so both are around during the transition.
What happened to the Schedule method?
It was removed in the 6th edition. The Schedule method was the simple "just hit these R-values element-by-element" path for small, simple buildings, and it was dropped because it didn't account well for thermal bridging. That leaves the Calculation and Modelling methods.
What's the difference between the Calculation and Modelling methods?
With the Calculation method you total the heat loss of the whole envelope and show it's no worse than a reference building, with trade-offs allowed (more glazing if the walls or roof do more). The Modelling method is a full energy/thermal simulation, used for complex or high-glazing designs.
Did the 6th edition make the insulation targets tougher?
No. The performance bar itself didn't move — the big R-value step-up landed in the 5th edition. The 6th edition mostly revised the methods, added better thermal-bridging accounting and new tables for windows and slab-on-ground, and tidied the NZS 4214 citation.
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