With the recent release of the H1/AS1 Sixth Edition, the Ministry of Business, Innovation and Employment (MBIE) has fundamentally changed how we calculate home performance. For homeowners, builders, and architects, this means the thermal performance of the entire window unit (not just the glass) is now under the microscope.

The Big Change: The “Schedule Method” is Gone

The most significant update in the 2026 transition is the removal of the Schedule Method as a “deemed to comply” pathway.

In the past, the Schedule Method allowed designers to use a simple table to ensure a building complied with basic insulation levels. However, as noted by Building Performance, this method is being phased out to encourage more accurate, whole-building thermal assessments.

This shift means all new builds must now demonstrate compliance through the Calculation Method or Modelling Method. You can no longer assume a window complies just because it is “standard double glazing”; you must now provide the actual Construction R-value of the frame and glass combined.

Understanding the 2026 R-Value Baselines

Under the new rules, New Zealand is divided into six climate zones. To meet the new requirements, window performance must hit significantly higher targets than in previous years:

Why uPVC is the “Compliance Shortcut”

Meeting an R-value of 0.50 is challenging with traditional framing. Standard aluminium conducts heat (and cold) easily. Even “thermally broken” aluminium frames often require expensive, high-specification glass to reach the new targets.

This is where uPVC window systems provide a distinct advantage. Because uPVC is a natural insulator, these frames naturally exceed the R0.50 requirement when paired with quality double glazing.

For designers, using high-performance windows acts as a “buffer” in the H1 Calculation Method. Because the windows perform so well, you have more freedom with your architectural design—such as larger glass areas or standard wall insulation—without failing the overall building energy budget.

Key Transition Deadlines

We are currently in a 12-month transition period that began on 27 November 2025.

• Until 26 November 2026: You can still submit building consents using the older 5th Edition (and the Schedule Method) in certain circumstances.
• From 27 November 2026: The 6th Edition becomes mandatory. Every consent application must use the Calculation or Modelling methods.

Future-Proofing Your Project

Adopting the 6th Edition standards now is about more than just legal compliance; it is about creating a warmer, healthier home that costs significantly less to heat. Choosing windows that exceed the minimum requirements today ensures better resale value and long-term comfort for years to come.

If you are currently in the planning stages of a build or renovation, we recommend discussing the new R-value requirements with your architect early in the process. At NK Windows, we provide full technical specifications to help our clients navigate these new standards with ease.

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