When you’re buying new windows, R-value is the number that tells you how well they resist heat flow. The higher the R-value, the better the insulation — and the warmer and drier your home will be in winter.
So what’s a good R-value for windows in New Zealand? The short answer: aim for R0.65 to R0.8.
Where does that come from?
For context, here’s how the New Zealand Building Code has moved over time:
- Before 2022, the minimum was R0.26 — achievable with standard aluminium frames and clear double glazing
- Since November 2022, R0.26 is no longer acceptable under H1/AS1
- The new minimum is higher, but R0.26 remains what many older homes were built to
R0.65–R0.8 sits well above the old minimum and represents genuinely good performance for a New Zealand home.
What gets you to R0.65–R0.8?
Your window’s R-value comes from two things: the frame and the glass. Different combinations of each give you different results.
Here’s how common combinations compare:
- Standard aluminium + low-E double glazing: around R0.30–R0.37
- Thermally broken aluminium + low-E double glazing: around R0.39–R0.50
- uPVC + low-E double glazing: R0.50–R0.69 depending on glass spec
- uPVC + premium low-E double glazing (argon, krypton): R0.69–R0.76
- uPVC + triple glazing: R0.73–R0.91
uPVC frames consistently outperform aluminium because the frame itself is thermally non-conductive. With standard aluminium, the glass does all the work — and the frame works against you. With uPVC, both the frame and the glass contribute to insulation.
Why the frame matters more than people think
Most of the conversation about windows focuses on glass — low-E coatings, argon fill, double vs triple. But the frame is responsible for a significant portion of heat loss in a typical window. A cold aluminium frame will cause condensation and radiate cold into a room even if the glass is excellent.
That’s why uPVC achieves better real-world performance than thermally broken aluminium at a similar price point — the frame isn’t a weak link.
What Livara can offer
The Ambiance uPVC systems we supply and install in South Taranaki achieve R-values in the R0.7–R0.8 range with standard double glazing specifications — and can go higher with upgraded glass options. We can walk you through the options for your specific project and climate zone.
Get in touch for a free quote and we’ll help you find the right specification for your home.