H1/AS1 6th edition calculation method tool
About this tool
The H1/AS1 6th edition calculation method tool helps designers and building professionals automatically check whether houses and other small buildings meet the energy-efficiency requirements of Building Code clause H1.
The tool generates a results sheet that can be included with building consent documentation.
Two versions of the tool are available:
- Full version – inputs are entered across multiple sheets with a detailed results summary.
- Basic version – all inputs and results are handled on a single sheet.
Both versions check compliance in the same way and are suitable for all housing and other buildings under 300 m² that do not include curtain walling.
How to use this tool
To use the H1/AS1 6th edition calculation method tool:
- Download and open the H1/AS1 Excel tool (Full or Basic version).
- Read the instructions before entering any data.
- Select the correct climate zone.
- Enter areas and construction R‑values for each building element.
- Enter values only into blue‑shaded cells and use drop‑down options where provided.
- Review the automatically generated results page to confirm compliance.
The tool performs built‑in checks to:
- prevent R‑values lower than the minimum allowed
- prevent unrealistically high values caused by data entry errors
- automatically calculate pass/fail outcomes.
The results sheet includes all entered data and calculations and is formatted for printing and submission as part of consent documentation.
Background
The calculation method is now the primary compliance pathway for H1/AS1 6th edition. The schedule method is being phased out and can only be used until 26 November 2026 under the H1/AS1 5th edition amendment 1.
The calculation method allows more design flexibility than the schedule method, including:
- wall glazing areas of up to 40% of gross wall area
- trade‑offs between different building elements, provided overall performance is met.
Designers must enter construction R‑values, not insulation product R‑values. These must be verified separately using approved methods such as:
- BRANZ House Insulation Guide (6th edition)
- NZS 4214 (as modified by H1/AS1 6th edition)
- relevant appendices within H1/AS1 6th edition.
The tool reflects BRANZ’s interpretation of H1/AS1 6th edition. and must be used in its complete, unmodified form. Accuracy depends on correct user input, and BRANZ does not accept liability for errors arising from incorrect data entry.