Thermal efficiency

What H1 asks of your windows

Building Code clause H1 sets a minimum R-value, a measure of how well something holds heat in, for the windows and doors in new homes. The rules stepped up twice.

• From 3 November 2022, windows and doors in new housing needed at least R0.37 anywhere in New Zealand.
• From 1 May 2023, climate zones 3 and 4 rose to R0.46, and zones 5 and 6 to R0.50.

Lower Hutt is in climate zone 3, so a new home in Lower Hutt with a building consent application lodged from 1 May 2023 needs windows and doors of R0.46 or better.

Work that doesn’t need a building consent, such as most like-for-like window replacements, doesn’t have to meet these rules. Better glass still makes a difference to how warm the room feels.

ThermalHeart+ frames

ThermalHeart+ frames have a polyamide thermal barrier through the core of the aluminium. Vantage rates them at almost double the thermal performance of standard, non-thermally improved aluminium windows and doors, based on its modelling of an average house.

Low-E double glazing

Our AGP units come with Solux-E or Solux Ultra Low-E glass, argon gas and a thermal spacer. Read more on the glass page.

Centrafix installation

Centrafix recesses the window or door back inside the wall, so less heat escapes around the frame. Vantage puts the gain at over 20%, from its modelling of joinery installed in 90 mm timber framing. Centrafix is available only in Metro Series ThermalHeart+ windows and doors, and it’s tested to pass EM9, Evaluation Method No. 9.

uPVC

Klima uPVC windows reach a 4.5 star rating under WEERS, the Window Energy Efficiency Rating System, when used with high performance glazing. See uPVC windows and doors.

Which combination you need

The answer depends on your house, the window sizes and what your designer has specified. Send us your plans and we’ll quote joinery to suit.