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H1 Calculator

We're committed to supporting the industry on its path to better buildings. To help the sector get up to speed with the latest changes to the Building Code, we have created this useful calculator to help projects submit for H1.

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.

Building Code H1/AS1 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.