Updated Changes to H1 | NZ Building Code

Today, the Ministry of Business, Innovation and Employment (MBIE) has updated the settings for compliance with the energy efficiency requirements of clause H1 of the Building Code.

MBIE has made targeted changes to the acceptable solutions and verification methods for H1 Energy Efficiency to improve clarity, flexibility and affordability for designers, builders and homeowners.

These changes follow a public consultation from December 2024 to February 2025 and build on the already announced decision to remove the Schedule Method as a ‘deemed to comply’ pathway, announced in July 2025. A review of the H1 settings in 2024 had identified opportunities to better balance upfront building costs and longer-term benefits.

The overall level of energy efficiency and insulation required remains unchanged.

The changes to H1 energy efficiency include: 

• more flexibility in insulation requirements with the Schedule Method being removed as a compliance pathway for insulation 
• clearer measurement rules, with the roof, wall and floor areas being measured using overall internal dimensions to ensure more consistency
• improved modelling methods in H1/VM1 and H1/VM2 to better align with modern building practices
• new requirements to ensure thermal bridging from wall framing is more accurately accounted for. A wall framing fraction of no less than 38% shall be assumed unless it can be demonstrated that a lower wall framing fraction is appropriate  for the building.
• enhanced tools and tables for windows and slab-on-ground floors to cover more common building scenarios.

The updated AS/VMs take effect immediately, and a 12-month transition period will run until 26 November 2026.

Designers have a 12-month transition period to fully adopt the changes by that date.

IAONZ will be working through these changes and providing further updates as required.

Read the updated H1 energy efficiency documents.

Summarised changes below :

Changes to H1/AS1

This acceptable solution is the sixth edition of H1/AS1. The main changes from the previous fifth edition amendment 1 are:

• The Schedule method has been removed from the acceptable solution.
• In the calculation method, the minimum construction R-value for slab-on-ground floors has been removed. The minimum construction R-values for roofs, walls, and floors other than slab-on-ground floors are now specified directly instead of a percentage of R-values in the reference building equation.
• For multi-unit dwellings and for mixed-use buildings, the building may now be treated as having either a single thermal envelope, or multiple thermal envelopes, when demonstrating compliance using the calculation method.
• The citation of NZS 4214 has been modified to enhance clarity of requirements for determining the thermal resistance of building elements containing thermal bridges.
• The method for determining the thermal resistance of framed walls has been revised to better address typical levels of thermal bridging caused by wall framing members. As a consequence, the wall R-value in the reference building heat loss equations has also been reduced.
•  The application of minimum construction R-values of heated ceilings, heated walls and heated floors has been clarified, and these minimum construction R-values no longer apply where heated ceilings, heated walls or heated floors are installed solely in rooms that contain a shower, bath or toilet.
• The method for determining the areas of roofs, walls and floors now requires the overall internal dimensions to be used.
• References have been revised to reflect the documents cited in this acceptable solution in Appendix A.
• Definitions have been revised to reflect the terms used in this acceptable solution in Appendix B.
• The performance table for windows and doors in housing in Appendix D. has been revised to better reflect commonly used window specifications.
• Appendix E. Thermal resistance of slab-on-ground floors has been revised to address buildings that have a mix of cladding types and buildings with slab edge insulation that does not cover the entire floor perimeter. The performance tables have also been expanded to include a greater range of slab area-to-perimeter ratios.
• The acceptable solution now refers to the Building Product Specifications for determining the thermal resistance of insulation materials. As a consequence, reference to AS/NZS 4859.1 has been removed from the acceptable solution with the applicable specifications located within the Building Product Specifications.
• Portions of text have been re-written to enhance clarity in the document and provide consistent language with other acceptable solutions and verification methods.
• Minor amendments have been made to correct typos, grammar, cross-references, punctuation, wording, and formatting of the document. This includes changes to headings, paragraphs, tables and figures, table and figure notes, and definitions. These amendments do not affect the level of performance required in the document but may assist in the interpretation of the requirements.

People using this document should check for amendments on a regular basis. The Ministry of Business, Innovation and Employment may amend any part of any acceptable solution or verification method at any time. Up-to-date versions of acceptable solutions or verification methods are available from www.building.govt.nz.

Changes to H1/AS2

This acceptable solution is the second edition of H1/AS2. The main changes from the previous first edition amendment 1 are:

• The Schedule method has been removed from the acceptable solution.
• The calculation method has been amended to provide flexibility for the construction R-values of all building elements of a proposed building’s thermal envelope. The minimum construction R-values for roofs and floors have been removed.
• For mixed-use buildings, the building may now be treated as having either a single thermal envelope, or multiple thermal envelopes, when demonstrating compliance using the calculation method.
• The citation of NZS 4214 has been modified to enhance clarity of requirements for determining the thermal resistance of building elements containing thermal bridges.
• The method for determining the thermal resistance of framed walls has been revised to better address typical levels of thermal bridging caused by wall framing members. As a consequence, the wall R-value in the reference building heat loss equations has also been reduced.
• The application of minimum construction R-values of heated ceilings, heated walls and heated floors has been clarified, and these minimum construction R-values no longer apply where heated ceilings, heated walls or heated floors are installed solely in rooms that contain a shower, bath or toilet.
• The method for determining the areas of roofs, walls and floors now requires the overall internal dimensions to be used.
• References have been revised to reflect the documents cited in this acceptable solution in Appendix A.
• Definitions have been revised to reflect the terms used in this acceptable solution in Appendix B.
• Appendix E. Thermal resistance of slab-on-ground floors has been revised to address buildings that have a mix of cladding types and buildings with slab edge insulation that does not cover the entire floor perimeter. The performance tables have also been expanded to include a greater range of slab area-to-perimeter ratios.
• The acceptable solution now refers to the Building Product Specifications for determining the thermal resistance of insulation materials. As a consequence, reference to AS/NZS 4859.1 has been removed from the acceptable solution with the applicable specifications located within the Building Product Specifications.
• Portions of text have been re-written to enhance clarity in the document and provide consistent language with other acceptable solutions and verification methods.
• Minor amendments have been made to correct typos, grammar, cross-references, punctuation, wording, and formatting of the document. This includes changes to headings, paragraphs, tables and figures, table and figure notes, and definitions. These amendments do not affect the level of performance required in the document but may assist in the interpretation of the requirements.

People using this document should check for amendments on a regular basis. The Ministry of Business,