To comply with the requirements of New Zealand Building Code clause E3, E3/AS1 requires that external walls of habitable buildings constructed of solid concrete, precast concrete or solid filled concrete masonry are required to meet the minimum insulation value of R0.6. This is the absolute minimum R-value for walls of habitable buildings in the NZBC.
For H1 Energy efficiency compliance, H1/AS1 and H1/VM1 have tables that supersede the requirements of NZS 4218:2004 Energy efficiency – Small building envelope, which is the cited version of this standard. The tables in NZS 4218:2009 Thermal insulation – Housing and small buildings are the same as those in H1/AS1 and H1/VM1.
When showing compliance with H1, Table 2(b) of H1/AS1 gives the minimum R-values when using the schedule and calculation methods.
When using the schedule method, only the (b) options in the table (that is, 1b, 2b, or 3b) should be used – see note 9 of the table. When using the schedule method, no R-value less than those given in the table is permitted.
When using the calculation method, use the (a) options in the table to calculate the heat loss for the reference building. The calculation method allows reductions in the values in the (a) options of up to 40%, for the proposed building, but the R-values used for the walls must not be less than the R0.6 required by E3/AS1 for solid construction.
Summarised from the BRANZ GUIDELINE Newsletter, October 2014.