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H1 Done. 
We’ve got your insulation solutions covered

Changes to Building Code clause H1 bring the biggest energy efficiency improvements in over a decade. Comfortech® is well prepared to help you with these changes.

Research shows that damp, mouldy, poorly ventilated homes affect the respiratory health of many New Zealanders. To help address these issues, MBIE has introduced the new 5th edition of H1/AS1 and H1/VM1 for housing and H1/AS2 or H1/VM2 for buildings greater than 300 m².   

This means significantly more insulation will be needed in the ceiling, walls and floors of new buildings from 1 May 2023. Learn more about the H1 Building Code changes below. 

What's New

Why is notching recommended

Why two layers of R3.6 are not recommended

How to avoid an unneccessary raised heel truss

Design Navigator and the BRANZ Home Insulation Guide

New Secondary Insulation Layer Wall Solution

We have developed a Secondary Insulation Layer Wall Solution, which enables the delivery of a 90mm timber frame wall, with a secondary insulation between 45mm thickness internal battens.

Learn More

Comfortech® H1 Residential Solutions

There is no one-size-fits-all solution for the new H1 Building Code changes, so our team has designed a range of residential solutions in partnership with the building industry that are flexible enough to cover a different building requirements.

Learn more about our solutions 

Frequently Asked Questions - H1 Changes

What is the H1 Building Code?

In 2021, MBIE consulted on changes to Acceptable Solution H1/AS1, AS2 and AS3 and Verification Method H1/VM1, VM2 and VM3 to increase the minimum requirements for insulation in new homes and buildings.

The purpose of the H1 Energy Efficiency Building Code change is to reduce the amount of energy needed to heat new buildings (housing and buildings under 300m2) by up to 40%. These changes will provide warmer, drier, and healthier buildings in New Zealand, with less impact on the environment. For buildings over 300m2 the targeted reduction is 23% of energy use, for heating and cooling.

When did the H1 Building Code change come into place?

MBIE is proceeding with changes to roof, window, wall, and underfloor insulation requirements, issuing the new H1/AS2 and H1/VM2 for large buildings, over 300m2 from 03 November 2022.  This aims to reduce the energy needed for heating and cooling by 23% on average across large buildings over previous minimum status quo requirements. 

What is an R-value?

An R-value is the thermal resistance rating used commonly in the building and construction industry to determine a materials ability to resit the transfer of heat.

What are Comfortech’s solutions to the H1 insulation changes?

Single-layer solution: For residential ceilings, a single layer of Pink® Superbatts® R7.0 at the new width of 460mm can be installed. Segments should be notched and fitted between the truss chord to seal the thermal bridge.

Double-layer solution: Comfortech’s two-layer solution uses a first layer of high-density Pink® Superbatts® insulation that is the combined height of the truss chord and the gap to the top of the ceiling batten. This layer would be 110mm for a 90mm truss chord and an R-value of R2.6 or 160mm for a 140mm truss chord and R3.0. The second layer is our new Pink® Superbatts®, over-width 460mm wide R4.5. Installed at right angles to the first layer, with this method, the thermal bridge is completely closed. A lower R-value second layer can be selected where another compliance pathway method has been chosen.

Why does Comfortech® recommend notching?
Can I install two layers of R3.6 insulation to meet the new code?
How do the H1 changes impact insulation installation?
What are the benefits of the H1 Energy Efficiency changes?
What is the schedule method?

It can only be used for houses where the area of glazing is less than 30% of the total external wall area and where the combined area of glazing on the east, south and west facing walls is 30% or less of the combined total wall area of these walls (for example: the north wall may have a greater area of glazing than 30% but this must be offset by reducing the area of glazing on the other three faces).

What is the Calculation method?

Under H1/AS1 5th edition amendment 1, the calculation method can only be used where glazing is 40% or less of the total wall area. Its advantage over the schedule method is that it allows a building with different building elements to be assessed as a whole, with adjustments being made between elements. For example, a ceiling R-value may be reduced if the wall or floor R-value is increased to compensate or if window R-values are increased. In no situations may R-values for roofs or walls be reduced below the minimum R-values set down by E3/AS1. The construction R-value for roofs, walls and floors in the proposed building must be at least 50% of the construction R-value of the corresponding building element in the reference building (calculated via the Schedule Method). The calculation method cannot be used to reduce the performance of building elements that have embedded heating systems.

What are the new climate zones boundaries?

There are six new climate zones, where the zones follow territorial authority (local government) boundaries to allow the insulation requirements to be easier to consistently administer and to better reflect the different climatic conditions experienced in each zone.

What is the modelling method?
How does the H1 Building Code change apply to alteration projects?

The new construction must meet the requirements of Clause H1, but the rest of the building does not have to be upgraded to comply with H1. The altered building must comply with Clause H1 to at least the same extent as it did before the alteration, and the overall energy efficiency of the building cannot be made worse by the alteration.

Are there new requirements for walls?
How does the H1 change impact heating?

With higher insulation R values, winter heating demand will be reduced. There is some risk in some scenarios, however that if a wholistic evaluation of the building throughout the year is not done (preferably via the modelling method) that summer cooling loads may in fact increase due to a more thermally efficient envelope retaining more heat. Therefore, window sizes and position as well as R values should be given careful consideration in this context.

How does H1 impact ventilation and vapour control?
Is a raised heel at the roof edge necessary?


Have questions about insulation?