NZ Building Code H1 climate zones and R-values

NZBC H1 sets the energy-efficiency targets for a new build, and the country is divided into six climate zones from the warm Far North down to Central Otago. The zone your site sits in decides the minimum construction R-values (measured in m²·K/W) you need to hit for the roof, walls, floor or slab, and glazing — so pinning the zone is the first thing to sort before you price insulation or windows.

The two editions in transition right now

There are two versions of H1/AS1 live at the moment, and it matters which one your consent runs under.

• H1/AS1 6th edition — published 27 November 2025 by MBIE and in force now for new building consents.
• H1/AS1 5th edition Amendment 1 — effective from 1 May 2023, and can still be used for consent applications until 26 November 2026. After that date only the 6th edition is valid.

What changed in the 6th edition

The R-values themselves haven’t drastically changed, but the way you demonstrate compliance has. The key changes are:

• The Schedule method has been removed — only the Calculation method (in H1/AS1) and the Modelling method (in H1/VM1) remain.
• Better thermal-bridging modelling for framed walls, with the wall reference R-value reduced as a result.
• Multi-unit buildings can now be treated as a single OR multiple thermal envelopes.
• The citation of NZS 4214 has been modified for clarity on thermal bridges.

Typical construction R-value targets across the zones are roof R6.6 in all zones, wall R2.0 (typically R2.6 with thicker framing), slab R1.5 (heated R2.5+), suspended floor R2.5, and windows R0.46 in Zones 1–4 or R0.50 in Zones 5–6.

The six climate zones

Zones 1 to 4 share the same construction R-values; the colder South Island zones (5 and 6) lift the floor/slab and glazing targets. Here’s how they break down:

• Zone 1 — warmest, upper North Island: Far North, Whangārei, Kaipara, Auckland, Rodney, North Shore, Manukau and more. Roof R6.6, wall R2, floor/slab R1.5, glazing R0.46.
• Zone 2 — Coromandel, Bay of Plenty, East Cape: Thames-Coromandel, Western Bay of Plenty, Tauranga, Mt Maunganui, Papamoa, Te Puke and more. Roof R6.6, wall R2, floor/slab R1.5, glazing R0.46.
• Zone 3 — top half of the North Island: Hamilton, Waikato, Taupō, Rotorua, Hastings, Napier, Hawke’s Bay, Wellington and more. Roof R6.6, wall R2, floor/slab R1.5, glazing R0.46.
• Zone 4 — central North Island uplands: Tararua, National Park, Ruapehu, Ohakune, Tongariro and the Wairarapa highlands. Roof R6.6, wall R2, floor/slab R1.5, glazing R0.46.
• Zone 5 — most of the South Island: Christchurch, Nelson, Marlborough, Tasman, Buller, Grey, Westland, Hokitika, Greymouth and more. Roof R6.6, wall R2, floor/slab R1.6, glazing R0.5.
• Zone 6 — coldest, Southern Lakes and Central Otago: Mackenzie, Tekapo, Twizel, Waitaki highlands, Central Otago, Queenstown-Lakes, Queenstown, Wānaka and more. Roof R6.6, wall R2, floor/slab R1.6, glazing R0.5.

Healthy Homes is a separate thing

Don’t confuse H1 with the Healthy Homes Standards, which apply to rentals and use their own numbers. For Healthy Homes the ceiling target is R2.9 in zones 1–2 or R3.3 in zones 3–6, with underfloor at R1.3 — separate from the H1 construction R-values above.