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24 February 2017

New Amendment to NZBC H1 Energy Efficiency

The New Zealand Building Code Clause H1 (NZBC-H1) first came into effect in 1992, with a second edition in 2000. The recently current edition was issued in 2007 and it included an updating of the various R-values listed in NZS 4218: 2004 (Energy Efficiency — Housing and Small Building Envelopes), for various building elements in each of the three climate zones. This Third edition remains effective until 30th May 2017.

The main change in this new Fourth edition (amendment 3), is the replacement of NZS 4218: 2004 with NZS 4218: 2009 as one of the primary 'Referenced Documents' for the purpose of the Acceptable Solutions and the Verification Methods. The tables printed in the Third edition are essentially as those in NZS 4218: 2009, but because NZS 4218: 2009 was issued after the Third edition of NZBC-H1 became effective, then NZS 4218: 2009 could not be used as the Referenced Document for the Acceptable Solutions and Verification Methods. This recent amendment corrects the situation, so the tables did not need to be repeated in NZBC-H1 (4th Ed) as they can be referenced in NZS 4218: 2009.

With regard to thermal performance, there are several other changes to the Acceptable Solution, H1/AS1:

  • The Acceptable Solution does not now include the use of foil insulation. — Clause 1.0.2,
  • Concrete slab-on-ground floors are "... deemed to achieve a construction R-value of 1.3, unless a higher R-value is justified by calculation or physical testing." — Clause 2.1.5,
  • Clause 4.2.1 of NZS 4218: 2009 is replaced by "The calculation method shall only be used where the glazing area is 50% or less of the total wall area." — Clause 2.1.6,
  • When the Calculation Method is being used to show compliance, Clause 2.1.7 clarifies the situation where the area of doors is greater than 6m² or 6% of the wall area.

During the Transition Period, (between 1st January 2017 and 30th May 2017), either the Third or Fourth Edition of NZBC-H1 may be used to demonstrate compliance by the Acceptable Solution or the Verification Method.

BRANZ has given notice that they will be updating and re-releasing their H1 Calculation Method Tool to reflect the permitted maximum glazing area from 40% to 50% of the wall area.

Showing compliance of the building by the Modelling Method, as described in NZS 4218 section 4.3 and Appendix G1.3 remains, using either a comparison of the performance of the Proposed Building with a Reference Building, or by showing that the Proposed Building has a BPI (Building Performance Index) which "...does not exceed 1.55." (Building Regulations clause H1.3.2E).

Through EcoRate Ltd I provide a service, using the Modelling Method, to demonstrate compliance of stand-alone housing, or dwellings within apartment complexes, with NZBC H1. The compliance analysis and assessment is undertaken using AccuRateNZ thermal simulation modelling software which was brought to New Zealand by EECA for Government's Home Energy Rating Scheme. In addition to NZBC-H1 compliance, the assessment gives an objective analysis which can be used to explore different materials, constructions, fenestration alternatives, differing orientations, etc. It can also be used for the tweaking of a design so as to maximise the passive thermal performance of the building.

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