The short answer
Sixth Edition is a workflow change, not a renamed Fifth Edition result.
H1/AS1 Sixth Edition removes the Schedule Method and makes the Calculation Method the acceptable-solution route for envelope thermal resistance. It also changes how framed walls, envelope areas, trade-off minimums, windows and slabs are treated.
If a project moves editions, rerun it under the Sixth Edition rules. Do not change the cover-sheet edition and carry the old result forward.
01 · Transition dates
Which H1/AS1 edition can I use?
H1/AS1 Sixth Edition became effective on 27 November 2025. Its document status says Fifth Edition, as amended, may still be used to show compliance for building consent applications submitted before 27 November 2026.
Before 27 Nov 2025
Fifth Edition
Sixth Edition states that it does not apply to applications submitted before its effective date.
27 Nov 2025-26 Nov 2026
Transition
Either edition can provide a pathway when its scope and requirements are followed consistently.
From 27 Nov 2026
Sixth Edition
The Fifth Edition transition has ended. Use the new documents or another valid means of compliance.
Keep one edition end to end.
Do not combine a Fifth Edition reference equation with Sixth Edition framed-wall, area or slab rules. Record the selected document edition on the calculation and consent evidence.
02 · Clause-by-clause
The complete Fifth-to-Sixth Edition change table.
This table separates the changes that affect a working H1 calculation from editorial renumbering. Clause references point to the official PDFs linked below.
Swipe horizontally to compare all four columns.
| Topic | Fifth Edition Amendment 1 | Sixth Edition | Primary clause |
|---|---|---|---|
| Available methods | Schedule Method, Calculation Method or the H1/VM1 Modelling Method could be selected within their limits. | The Schedule Method is removed. H1/AS1 now contains the Calculation Method; H1/VM1 remains the modelling route. | Fifth 2.1.1.1; Sixth 2.1.1.1 |
| Reference opaque wall | The Calculation Method reference-building equations use R2.0 for the opaque 70% of gross wall area. | The reference opaque-wall value is R1.6 in every climate zone, reflecting the revised framed-wall method. | Fifth Table 2.1.3.4A; Sixth Table 2.1.2.7 |
| Framed-wall R-value | NZS 4214 applies. Studs, dwangs and plates are included, but some opening, corner and junction framing could be excluded. | Assume at least 38% wall framing unless a lower whole-building fraction is demonstrated. H1/AS1 also modifies NZS 4214 clause 5.7.1(a). | Fifth 2.1.4.3; Sixth 2.1.3.1-2 |
| Trade-off minimums | Roofs, walls and floors in the proposed envelope had to achieve at least 50% of the corresponding reference-building R-value. | Direct minimums replace the percentage rule: roof R2.6, wall R1.0 and non-slab floor R1.3. | Fifth 2.1.3.8; Sixth 2.1.2.11 |
| Slab minimum | The 50%-of-reference rule also applied to slab-on-ground floors in the Calculation Method. | There is no separate slab-on-ground minimum. The slab still contributes to the proposed-vs-reference heat-loss comparison. | Fifth 2.1.3.8; Sixth 2.1.2.11 |
| Envelope areas | The method did not state one general overall-internal-dimension rule for the roof, wall and floor terms. | Net roof, thermal-envelope floor and net wall areas use overall internal dimensions at the finished internal face, including partition thickness. | Sixth 2.1.2.10 |
| Multi-unit and mixed-use | The Calculation Method did not provide the new express choice of one envelope or multiple envelopes. | Eligible mixed-use buildings and multi-unit housing may be assessed as one thermal envelope or as multiple thermal envelopes. | Sixth 2.1.2.2-3 |
| Heated elements | Schedule values applied to heated ceilings, walls and floors whenever those heated elements formed part of the envelope. | The minimums are retained but no longer apply where the heated element is installed solely in rooms containing a shower, bath or toilet. | Fifth 2.1.1.3; Sixth 2.1.2.12 |
| Windows and doors | Housing window and door performance values appeared in Appendix E. | The table moves to Appendix D and is revised to better reflect commonly used window specifications. | Fifth Appendix E; Sixth Appendix D |
| Slab calculations | Appendix F provided the slab-on-ground tables for the listed whole-perimeter scenarios. | Appendix E adds mixed cladding and partial edge-insulation treatment and expands the area-to-perimeter ranges. | Fifth Appendix F; Sixth Appendix E |
| Insulation specifications | H1/AS1 directly referenced AS/NZS 4859.1 for verifying insulation-material R-values. | The applicable product requirements move to the Building Product Specifications, which must be used with H1/AS1. | Fifth 2.1.4.2; Sixth 1.2.3 and 2.1.3.3 |
The section and appendix numbers also move because removing the Schedule Method closes the numbering gap: the Calculation Method changes from Fifth Edition 2.1.3 to Sixth Edition 2.1.2, windows move from Appendix E to D, and slabs move from Appendix F to E.
03 · Worked comparison
One wall term shows why the old result cannot simply be relabelled.
Consider only the reference-building wall term for an illustrative Zone 3 building with 100 m² of gross wall area. Both editions assign 70% to opaque wall and 30% to wall glazing, so the opaque reference area is 70 m².
Fifth Edition reference wall
70 m² ÷ R2.0 = 35.00 W/K
Table 2.1.3.4A uses R2.0 for the opaque-wall reference term.
Sixth Edition reference wall
70 m² ÷ R1.6 = 43.75 W/K
Table 2.1.2.7 uses R1.6 for the opaque-wall reference term.
This is not a complete H1 pass/fail example.
The whole calculation must also include roof, floor, glazing, doors and skylights. More importantly, the proposed framed-wall construction R-value can change under the Sixth Edition 38% framing rule, and envelope areas must follow the new overall internal-dimension convention. The 8.75 W/K difference in this isolated reference term cannot be treated as a free design credit.
04 · Continuity
What did not change?
The Sixth Edition revises the workflow without replacing the central proposed-vs-reference structure of the Calculation Method.
- The scope remains all housing and other buildings with no more than 300 m² of occupied space, subject to the stated exclusions.
- The Calculation Method still compares the proposed building with a climate-zone reference building.
- Proposed temperature-specific heat loss must be no greater than reference heat loss.
- Wall glazing remains limited to 40% of gross wall area for the Calculation Method.
- The reference building still uses a 70% opaque wall and 30% wall-glazing split.
- The proposed heat-loss equation still adds area divided by construction R-value for each distinct envelope element.
- Six territorial-authority-based climate zones remain in Appendix C.
- H1/VM1 remains available where the Modelling Method is selected or the Calculation Method is unsuitable.
05 · Project handover
A practical Fifth-to-Sixth Edition migration checklist.
- 01
Lock the pathway and edition
Confirm the building is within H1/AS1 scope, record the application timing, and state “H1/AS1 Sixth Edition” on the calculation evidence.
- 02
Reconfirm the climate zone
Use Appendix C’s territorial-authority table as the authority. A postcode lookup is a useful estimate, not the source of truth.
- 03
Remeasure the envelope
Apply overall internal dimensions to net roof, thermal-envelope floor and net wall areas. Keep gross wall, wall glazing, opaque doors and skylights traceable.
- 04
Recalculate every framed wall
Use at least 38% wall framing unless the project demonstrates a lower whole-building fraction. Include plates, dwangs, corners, junctions and opening framing.
- 05
Refresh windows and slabs
Use the Sixth Edition Appendix D window values and Appendix E slab method, including mixed cladding and partial edge insulation where applicable.
- 06
Run the Sixth Edition heat-loss comparison
Use the current Table 2.1.2.7 reference equations and expand the proposed equation for every distinct area and construction R-value.
- 07
Check the non-tradeable limits
Confirm wall glazing is no more than 40% and that all applicable roof, wall, non-slab floor and heated-element minimums are satisfied.
- 08
Package reproducible evidence
Retain area take-offs, complete construction build-ups, framing basis, product sources, window and slab inputs, assumptions and the proposed/reference result.
Useful Thermly checks
Build for the post-transition rules
Start the next project with the Sixth Edition Calculation Method.
Bring plan areas, complete construction R-values, the heat-loss check and source-backed evidence together in one review trail.
06 · Common questions
H1/AS1 edition transition FAQ.
Can I still use H1/AS1 Fifth Edition in 2026?
Yes, for building consent applications submitted before 27 November 2026. MBIE states that Fifth Edition, as amended, can be used to show compliance until 26 November 2026.
When does H1/AS1 Sixth Edition become mandatory?
For this acceptable-solution pathway, the Fifth Edition transition ends on 26 November 2026. Applications submitted from 27 November 2026 need to use the new documents or another valid compliance pathway.
Does H1/AS1 Sixth Edition still have the Schedule Method?
No. Sixth Edition removes the Schedule Method from H1/AS1. Its acceptable-solution route for envelope thermal resistance is the Calculation Method, while the Modelling Method remains in H1/VM1.
Did all of the H1 R-values change?
No. Some reference-building values are unchanged, but the opaque-wall reference changes from R2.0 to R1.6. Sixth Edition also replaces the Fifth Edition percentage-based trade-off minimums with direct roof, wall and non-slab-floor minimums.
Can I reuse a Fifth Edition H1 calculation for Sixth Edition?
Do not simply relabel it. Recheck the area convention, framed-wall construction R-values, reference equation, direct minimums, window values and slab method under the Sixth Edition clauses.
07 · Primary references
The documents used for this comparison.
Thermly checked the comparison against the official H1/AS1 Fifth Edition Amendment 1 and H1/AS1 Sixth Edition documents. Always check MBIE for later amendments before relying on a compliance pathway.
- 01
MBIE — H1/AS1 Fifth Edition Amendment 1
The transitional Schedule and Calculation Method requirements effective from 4 August 2022. Open the Fifth Edition PDF
- 02
MBIE — H1/AS1 Sixth Edition
The current Calculation Method, document status and complete list of changes from Fifth Edition. Open the Sixth Edition PDF
- 03
MBIE — H1 Energy Efficiency
Current documents, effective dates, transition dates and amendment history. Open the H1 document hub
- 04
MBIE — Increasing the flexibility of H1 energy efficiency
MBIE's policy summary and announcement of the new documents. Read the change announcement
- 05
MBIE — Building Product Specifications
Product standards and specifications referenced by Sixth Edition H1/AS1. Open the specifications
This page is a technical summary, not a substitute for the cited acceptable solution or project-specific professional advice.