The building industry is prepared for the coming increase in demand for ‘Low E’ glazing as new thermal performance requirements are phased in across the country, Window & Glass Association of New Zealand Chief Executive Brett Francis says
Clause H1 of the New Zealand Building Code, which regulates the energy efficiency of buildings, was updated in November last year and the first phase of implementation began on Thursday 3 November.
This will see initial increases in thermal resistance or R value requirements for roofs, walls, floors, and windows and doors in effect for any buildings submitted for consent from this date. Further increases follow on 1 May 2023 and again on 2 November 2023.
Any building consents lodged from Thursday, 3 November 2022, will need to satisfy the first phase of these new requirements.
And while the increases in R value requirements for windows and doors will vary depending on a building’s type and location, for many, the initial increases will require a change in glazing solutions.
Tools available to determine requirements
Three key things are needed to determine the new requirements a building is subject to: the building type – being housing, other buildings up to 300m2 or other buildings greater than 300m2, the site address of the building to determine which of six new Climate Zones it’s in, and when the consent application will be submitted.
We’ve created a simple tool for Housing requirements in the H1 Info Hub on the Association’s website and have Quick Reference Guides for all the building types available also.
For Housing, the first phase of implementation is a move to R0.37 for windows and doors in houses planned for all areas of the country between 3 November 2022 and 31 April 2023.
This means minimum compliance can be achieved through a change in glazing, and specifically through the use of high performance double glazed Low E IGUs – or Insulated Glass Units, in aluminium frames as we know them.
These glazing units use Low E or low emissivity glass, which has a lower rate of heat-loss due to the use of extremely thin layers of silver and/or other low emissivity material on one side of the glass, which is then enclosed in double or triple glazing to protect the coating. The use of inert gas like argon, rather than normal air, between the layers of glazing further improves the insulating properties of the units.
Thermally broken aluminium, uPVC and Timber frames with double-glazed Low E IGUs will also meet or exceed the standard. And of course, higher specification solutions are encouraged and will result in more thermally efficient homes.
A doubling in thermal performance ahead
Two more phase-in periods will see further increases in requirements that will result in an overall near doubling of thermal performance for windows and doors in New Zealand homes, making them much more energy efficient.
In Zones 1 and 2, encompassing Auckland where 70 percent of the country’s residential construction occurs, there are no further changes for housing until 2 November 2023, when requirements lift to R0.46 and demand different window frame solutions.
In cooler regions, that move comes earlier, in 1 May 2023, moving to R0.46 in Zones 3 and 4, and R0.50 in Zones 5 and 6.
At these levels, the cold aluminium frames that are a mainstay in so many New Zealand homes will become a thing of this past. Instead, compliance will require double-glazed Low E IGUs combined with thermally broken aluminium, uPVC or timber frames.
A note on other buildings
Most of the changes in the commercial sector – including for the likes of hotels, schools, restaurants, retirement villages and more, are implemented in this first phase.
For such buildings up to 300m2, Zones 1 and 2 move to R0.37, and will be the only segment to shift again on May 1 2023 to R0.46. Zones 3 and 4 will sit at R0.46, and Zones 5 and 6 at R0.50.
For buildings greater than 300m2, Zones 1 and 2 will move to R0.33, Zones 3 and 4 to R0.37, and Zones 5 and 6 split into R0.40 and R0.42 respectively.
More resources and regular updates are available from the Window & Glass Association of New Zealand’s H1 Info Hub at https://www.wganz.org.nz/h1-information-hub/