Thermal Efficiency

In 2021, the Ministry of Business, Innovation, and Employment (MBIE) announced its new requirements for thermal efficiency in the construction industry under the H1 Energy Efficiency standards of the New Zealand Building Code (NZBC), resulting in several shifts in thermal efficiency for windows and doors.

New zones. Healthier homes.

Exterior joinery is responsible for 35-50% of heat loss in a building when using aluminium joinery, identifying it as an area that needed minimum standards raised.

In November 2022, New Zealand moved from 3 climate zones to 6 to allow for a nuanced approach to climatic factors and window sustainability. All zones required a minimum 0.37 R-Value from this date, with cooler zones having another interim increase before all zones fully transition to the final performance requirements from November 2023 and all parts of the country having similar level of window insulation requirements.

  • Zones 1-4: R0.46
  • Zones 5-6: R0.50

What does this mean?

The updated R-Values mean that the windows and doors of new builds will be more resistant to heat flow. Preventing heat from escaping in winter and entering in summer for year-round comfort.

We have thermally efficient options available for compliance with the updated H1 of the NZBC, whilst ensuring warmer, drier and healthier homes:

  • ThermalHeart+
  • Klima Series uPVC
High quality windows and doors
Joinery auckland


ThermalHeart+ is our innovative system that marries together the latest developments in thermal technology for windows and doors to nearly double the thermal performance of windows and doors.

  • ThermalHEART® thermally-efficient frames
  • The AGP System® glass for warmer, drier and healthier homes
  • Centrafix™ installation method to increase thermal performance by over 20%.

Klima Series uPVC

Klima Series is our high-durable range of uPVC joinery, made from super-thick uPVC profiles to provide maximum thermal insulation, high-quality weather resistance, and strength in high wind zones.

H1 Energy Efficiency FAQs

Credit: Interview with Simon Farrell-Green, originally published in HERE magazine.

How is the Building Code changing?

What is changing?

The H1 clause of the NZCB concerns the efficient use of energy and sets the physical conditions for energy performance of buildings. Changes that affect glazing are the increases to the minimum R-Value of the window or door unit. The R-Value measures the ability of an insulation material to resist heat transfer from one side to the other. In winter, the heat attempts to exit whilst in summer it enters. A higher R-Value can provide more resistance to heat flow. 

How much more efficient do dwellings have to be?

From November 2023, all new homes in the North Island (Climate Zones 1-4) will require a R-Value minimum of R0.46. The cooler areas of the lower South Island (Climate Zones 1-5) will require R0.50. 

Why have the regulations changed?

The updated H1 standards keep Aotearoa in line with current international guidelines. The changes have come to provision as part of the larger initiative to get New Zealand to carbon net zero by 2050. We can anticipate seeing future changes coming with bigger steps toward achieving carbon neutrality.  

What are the new requirements for my build?

How do I work out what level of performance I'm going to need?

If the building is less than 300m2 (which is most new houses) and glazing is less than 30% of the total wall area, there are tables within the acceptable solution that set out minimum R-values depending on where you live. If the building is larger than 300 m2 or glazing takes up more than 30% of the wall area, there are other ways to establish minimum performance levels, such as calculating or modelling where thermal performance levels are averaged over all joinery units. 

Climate Zones 1-4 require a minimum of R0.46 (North Island) and Climate Zones 5 and 6 a minimum of R0.50. There are special conditions for opaque doors, and skylights which require a higher R-value again. 

What will this gain?

Any thermal-performance improvements to the building envelope help to reduce the energy required for heating and cooling. Contributing to keeping heating costs down while delivering warmer, drier and healthier homes. 


What joinery options will achieve the Building Code H1 requirements?

What will comply?

The updated R-Values will require either uPVC joinery or thermally broken frames with high-performing low-E glass and argon gas inside the double glazing. 

How have Windowmakers met the new requirements?

We have developed thermally efficient products to achieve the updated R-Values to ensure code compliance and deliver warmer, drier and healthier homes:

ThermalHeart+ is our innovative window and door system that marries together the three crucial components of a window unit to nearly double the thermal performance of standard windows and doors:

  • ThermalHEART® thermally efficient frames 
  • The AGP System® glass for warmer, drier, and healthier homes 
  • Centrafix™ installation method to increase thermal performance by over 20% 

Klima Series uPVC is optimized to withstand New Zealand’s high UV levels and other unique conditions. The super thick uPVC profiles provide maximum thermal insulation, high-quality weather resistance, and strength in high wind zones. 

Another question?