Building Code: H1 Calculator

Supporting New Zealand to build better homes

Building Code H1/AS1 Calculation Method

New Zealand Green Building Council is committed to supporting the building and construction sector to design and build better homes and buildings for Aotearoa New Zealand.

In November 2021, MBIE announced changes to section H1 of the Building Code. At this stage, these changes are due to come into force from November 2022.

To build awareness of the change involved, this calculator  has been developed to help residential projects submit for H1 using the calculation method.

The NZGBC webinar (together with MBIE and BRANZ) on the new H1 changes can be found here. It gives a short tutorial on the calculation method.


The most basic method of complying with the new H1 acceptable solution (AS1) for buildings under 300m2 (i.e. homes) is for every wall, roof, floor, window and door to have an R-value greater than those found in a schedule of R-values - this is known as the 'schedule method'.

The schedule method is often not the most cost-effective way of complying with H1. This is especially true with the tougher roof, floor and window R-values coming into force in November.

The acceptable solution allows projects to trade-off lower R-values in parts of the envelope in return for higher R-values elsewhere. This is known as the calculation method.

Use the H1 Calculator