By law, since 1978 all new homes and major renovations in New Zealand have had to be thermally insulated. Since November 2007 the standards of insulation required for new homes and major renovations have been markedly increased.

The minimum requirements for energy efficiency in house design and construction are spelled out in the Building Code's energy effectiveness clause H1. The standard AS/NZS4859.1 sets the testing and labelling requirements for insulation materials used in the home and whether they comply with the requirements of H1.

The new requirements

The new minimum insulation requirements, including double glazing, were introduced in stages around the country.

All new homes and major renovations in Zone 3 (see map) have had to comply with the requirements since November 2007. Zone 2 was included in June 2008 and Zone 1 from 30 September 2008.

The tables below show an example of the new overall R values for wall, roof, floor and glazing required in different parts of the country for non-solid (timber-framed) construction houses.

Full details of insulation requirements can be obtained from the compliance documents of the Building Code.

Zones 1 & 2 - North Island excluding the Central Plateau

Zone 3 - South Island and the North Island Central Plateau

To achieve the required R2.0 for the walls of a Zone 3 timber house, for example, you need to install an insulation product with an R value between 2.2 and 2.8. This is because the higher R value for the insulation product offsets the lower R value of the timber framing (see The basics).

There are different R requirements for solid construction houses. Details can be found in Clause H1 of the Building Code.