Want to be ‘All over H1’? Clause H1 of the New Zealand Building Code, which regulates the energy efficiency of buildings, is undergoing its biggest changes in more than a decade. The first phase of implementation began on Thursday 3 November 2022, with a further set of requirements beginning from 1 May 2023.


Tumu Building Supplies is committed to providing you with the information you need to work within the rules. Currently the information provided here follows that provided by MBIE. In the New Year, ‘All Over H1’ will also include detailed supplier solutions and related products, which will assist the design process for most standard construction methods.


The update to Clause H1 aims to help make new buildings warmer, drier and healthier and therefore reduce the energy and environmental impact needed to heat them. The changes are the biggest energy efficiency updates to the acceptable solutions and verification methods in more than a decade.


The H1 Clause of the Building Code regulates the energy efficiency of the built environment – covering wall, floor and ceiling insulation, as well as the thermal performance of windows and doors. There are major increases in thermal performance requirements across the building envelope, indicated through higher construction R-values for different building elements.

Housing + building less than 300m2

The new housing and small building insulation requirements are the same. The only difference between them is the transition date for the new final values to come into effect.

Introduction to R-Values in H1

Construction R-values in H1

An R-value is the measure used to describe the ability of a material or system to resist the transfer of heat. The higher the R-value, the better the thermal resistance.


There are two types of R-values commonly used in the construction industry:

1. Material R-values

The thermal performance of individual products eg, insulation.

2. Construction R-value

The total thermal perform­­­ance (R-value) of a typical area of a building element. For a wall this would be derived from the R-values of the cladding, insulation material and a ‘typical area’ of wall framing.

The Building Code clause H1 documents specify construction R-values, not the R-value of the insulation product to be installed.

This is an important difference. For example, an R5.0 thermal ceiling insulation blanket may be used but the construction value of the ceiling may only be R4.0 once the total ceiling construction design is accounted for. 

Two sets of requirements, three transition dates

Minimum insulation requirements differ across three types of buildings:


Small buildings – under 300m2.

Large buildings – over 300m2.

Housing covers all types of residential housing of any size including standalone houses, townhouses, and apartments. All other buildings are defined by size; small buildings under 300m2, and large buildings over 300m2.


The new housing and small building insulation requirements are the same. The only difference between them is the transition date for the new final values to come into effect, as outlined below.


Large building requirements differ from housing and small building requirements.


Industrial, assembly service and ancillary buildings, as well as outbuildings, currently sit outside the scope of this work. However, where there is an office within a warehouse or industrial building that office would have to comply with the new requirements.

Buildings more than 300m2

The new requirements for large buildings aim to reduce the emissions and energy used when heating and cooling a larger building by 23% on average over previous minimum status quo requirements.

New climate zones

Previously, New Zealand was divided into three climate zones – Zones 1 and 2 for most of the North Island and Zone 3 for the South Island and the central plateau. There are now six climate zones across New Zealand, and the new insulation requirements are tied to the zones.

What building work is affected?

These changes only affect new construction or existing properties undergoing changes to the external thermal envelope, which will require a building consent. Tenancy retrofit insulation standards are separate and not covered by the Building Act and Building Code.  

When are the changes happening?

Improvements to the requirements under H1 were published by MBIE in November 2021 and, more recently, the transition periods for housing were updated.

From 3 November 2022:

All changes to ‘Buildings more than 300m2’ are in place.


All changes to ‘Buildings less than 300m2’ that are not housing are in place.


For Housing, regardless of size, everything is on hold until May 2023 except an interim increase to the R-value of windows and doors is in effect.

From 1 May 2023:

Increases in thermal performance for ‘Housing’ will take effect on 1 May 2023, following an extension on the transition period. This includes ceilings, walls and floors.

From 2 November 2023:

Windows and doors for ‘Housing and buildings under 300m2’ will see a further increase in November 2023.

How to determine the requirements of your build

Three key things are needed to determine the new requirements a building is subject to:

1. The building type

Is it housing, a buildings up to 300m2 or a building greater than 300m2?

2. Site address

The site address of the building to determine which of six new Climate Zones it’s in.

3. Consent

When the consent application will be submitted.

Browse through the H1 Made Easy Guide for detailed supplier solutions