Shut the Door! Keeping Your Home Warm and Dry with H1

Published: 30 November 2023

New Zealanders are seeing a bigger push towards warmer, drier homes, and more sustainable living.  This is beginning to impact the construction industry.  On the 2nd of November 2023, the New Zealand Building Code changed to reflect this through clause H1 of the building code, which focuses on energy efficiency.  Clause H1 has new and increased requirements for performance of the thermal envelope of a residential building, or a building under 300m², so that the building stays warm in winter, cool in summer, and dry all year round.

The thermal envelope of a building is the divider between its conditioned space and its unconditioned space.  An unconditioned space is outdoors, as well as any region of the building that is not intentionally heated, like a garage, a ceiling cavity or a conservatory.  The thermal envelope is any building product, for instance, a wall, a roof, a window or a door, that divides these spaces.

The H1 Energy Efficiency clause update is concerned with R-Values.  This number represents the building component’s resistance to the transfer of heat through it – if a material lets heat pass through it with little resistance (like a metal teaspoon getting hot enough to hurt from a cup of hot coffee), then it has a low R-Value, close to 0 m²K/W.  If a material prevents heat from easily passing through it (like a ceramic mug holding hot coffee getting warm, but not hot enough to hurt), then it has a high R-Value, above 0.5 m²K/W.

Superior Doors’ range of thermal envelope doors are the perfect way to promise a warm, dry home, and meet H1 requirements. The company recently obtained independently accredited test results demonstrating that their range of thermal envelope doors significantly exceed the increased minimum R-Value requirements under clause H1 of the New Zealand Building Code.

Superior Doors range of thermal envelope doors are suitable for a wide range of applications:

R-values in the table above are calculated on a representative door leaf size of 1980 mm x 810 mm.  Naturally, door leaves of any size are available. R-Values include a surface coefficient, and exclude the impact of any framing.

Different building components have different minimum R-Values under the new legislation, with the R-Values for building components adjusting to different climate regions of the country.  Minimum R-Values for residential doors in climate zones 1-4 is 0.46 m²K/W, and in climate zones 5 & 6 is 0.5 m²K/W.

Image Credit: Ministry of Business, Innovation & Employment, Hīkina Whakatutuki. H1 Energy Efficiency, Acceptable Solution H1/AS1. Wellington: New Zealand Government, Te Kāwanatanga o Aotearoa, 2023. p. 24.

Superior Doors is a family owned and operated business based in Auckland, New Zealand. Over the last 25 years, Superior Doors is proud to have grown to become New Zealand’s largest interior door manufacturer.  All products are manufactured in New Zealand, by New Zealanders, using all New Zealand sourced and supplied raw materials.

For more information, see: