COMPLIANCE PATHWAYS & METHODS
Compliance Pathways
There are different ways to show that a building complies with the Building Code. One way is through the use of acceptable solutions or verification methods. For the insulation requirements of H1 Energy Efficiency, there are two updated acceptable solutions and two verification methods that can be used to demonstrate that a building’s thermal resistance will meet the new requirements. Thermal resistance - how well the building is insulated - is specified in these documents using R-values.
Alternative solutions
If designers or builders want to comply with the Building Code performance requirements directly, they may also choose to use an alternative solution as a compliance pathway.
This will usually require specific design and input from suitably qualified people, such as architects or engineers. Alternative solutions are not deemed to comply with the Building Code and must be assessed by the relevant Building Consent Authority on their individual technical merits.
For the insulation requirements, the alternative solution must satisfy the Performance Criteria in clause H1.3.1(a).
Verification Methods
The verification methods for H1 (H1/VM1 & H1/VM2) contain rules for design professionals using computer modelling and software to determine the minimum amount of insulation required in a building and to demonstrate compliance with the Building Code. Only H1/VM1 can be used for housing and ‘Buildings less than 300m²’. Read more about H1/VM2 on pages 18-19.
H1/VM1: This verification method can be used for all housing (of any size) and some other types of small building with an area of occupied space up to 300m² – the same building types that fall under H1/AS1. However, unlike H1/AS1, there are no limitations on the type of construction elements and specific designs the document covers for these buildings.
The method used to determine the minimum insulation requirements is based on computer modelling and known as the Modelling method. Users of this method are expected to have specific training and expertise to conduct the simulations.
Acceptable Solutions
The acceptable solutions for H1 (H1/AS1 & H1/AS2) contain tables and a simple calculation method to determine the R-values in a building. Only H1/AS1 can be used for housing and ‘Buildings less than 300m²’. Read more on H1/VM2 on pages 18-19.
H1/AS1: This acceptable solution can be used for all housing (of any size) and other types of small building with an area of occupied space up to 300m². Housing and small buildings have similar heating and cooling requirements. To determine the minimum insulation requirements, this document contains two methods – Schedule and Calculation.
These methods are intended to be used by anyone but have limitations for when they can be used. This cannot be used if your building has a curtain wall.
Compliance Methods
The H1 Clause of the Building Code regulates the energy efficiency of the built environment – covering wall, floor and ceiling insulation, as well as the thermal performance of windows and doors. There are major increases in thermal performance requirements across the building envelope, indicated through higher construction R-values for different building elements. Read more on the different methods used to determine construction R-value below. Within the acceptable solutions and verification methods for H1 Energy Efficiency, there are three methods to comply with the minimum R-values for building.
• The Schedule Method (table)
• The Calculation Method (simple online calculator)
• The Modelling Method (software)
Which method the designer decides to use will depend on a variety of factors, including but not limited to:
• Whether the building is smaller or larger than 300m².
• The size of the glazing area of the building.
• The orientation of the building.
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, walls (usually external), 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:
a) The glazing area is 30% or less of the total wall area.
b) 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.
c) The skylight area is no more than 1.5m2 or 1.5% of the total roof area (whichever is greater).
d) The opaque door area is no more than 6m2 or 6% of the total wall area (whichever is greater).
BRANZ provides a Schedule Method tool HERE
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.
BRANZ provides a Schedule Method tool HERE
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%.