Energy Efficiency (H1) - Compliance Methods

The Schedule Method

This method contains tables of minimum construction R-values for different building elements. A building complies with this method if its thermal envelope components – roof, (usually external) walls, windows, doors, skylights and floor – are insulated to meet or exceed R-values from the tables. The R-values vary depending on the climate zone a building is in.

Designers use a different set of tables if building elements contain embedded heating systems in ceilings, walls or floors.

The Schedule method shall only be used where:

• The glazing area is 30% or less of the total wall area; and
• The combined glazing area on the east, south, and west facing walls (refer to Appendix D) is 30% or less of the combined total area of these walls; and
• The skylight area is no more than 1.5 m² or 1.5% of the total roof area (whichever is greater);
• The opaque door area is no more than 6 m² or 6% of the total wall area (whichever is greater).

You can access BRANZ’s Schedule method tool HERE.

The Calculation Method

This method includes simple equations and allows a building to have different insulation combinations, as long as the overall thermal performance is comparable to or better than the reference* building, which is insulated in accordance with the Schedule method.

In practice, this means it allows trading off between elements so you can use higher R-values for some elements than in the table shown and lower R-values for others.

However, there are limits. Using the calculation method, the minimum R-value for a floor, wall or roof building element is 50% of the schedule method R-value for that building element. There is no minimum for doors and windows.

Using the calculation method, the window area of the building can be no greater than 40% of the total wall area.

*The ‘reference’ building heat loss equations can be calculated using Table 2.1.3.4A in H1/AS1. See table HERE.

You can access BRANZ Calculation Method tool HERE.

The Modelling Method

This method provides the greatest amount of flexibility. It is used to assess the energy performance of a proposed building by using a simulation of the building to predict its space heating loads and cooling loads. This is compared with the space heating loads and cooling loads of a reference building that is the same shape, dimensions, and orientation as the proposed building, as well as building elements with the relevant construction R-values.

Verification of the design is achieved by using computer modelling to demonstrate that the energy use of the proposed building design does not exceed the energy use of the reference building described above and in more detail in Appendix D of H1/VM1.

This method is used if the window area of a building is greater than 40%.