NZS 4218:2009 Calculation Method Tool
This tool calculates heat loss for the calculation method of NZS 4218:2009. It is not a replacement for NZS 4218:2009, and designers are advised to obtain a copy from Standards
What to do:
read the instructions first.
NZS 4218:2009 Calculation Method Tool - this is now compatible with Excel 2010.
About the NZS 4218:2009
Calculation Method Tool
Instructions for using the NZS 4218:2009 Calculation Method Tool
About the NZS 4218:2009 Calculation Method Tool
What this calculation tool does
to select the climate zone and wall construction type(s) and accurately enter all area and construction R-values for the various building elements. The tool then applies the calculation method
automatically, and pass/fail compliance is determined.
Compliance with NZBC clause H1
NZS 4218:2009 is NOT currently an Acceptable Solution under clause H1 of the NZBC. The H1 Calculation Method Tool may be used as an Alternative
Only the following designs are eligible to use this tool to demonstrate compliance with NZBC clause H1:
- Housing (all types, any
- Buildings other than housing with a net lettable area of no more than 300 m².
- Buildings other than housing with a net lettable area of greater
than 300 m² MAY use this tool. However, NZS 4243 is usually used.
This tool is NOT the calculation method of NZS 4243 and MUST NOT BE USED for this
This tool is NOT the calculation method of NZS 4218:2004 or H1/AS1 and MUST NOT BE USED for this purpose.
Refer to New Zealand
Building Code clause H1 Energy efficiency Third Edition for full details.
Measurement of areas
Refer to NZS 4218:2009 for definitions of element areas and how to measure them.
Designers must input construction R-values for the roof, walls and floor. This is NOT the same as the insulation R-value. Refer to NZS
4218:2009 for the definition of construction R-values.
The BRANZ House Insulation Guide Preview/Buy
gives construction R-values for the most common construction types used in residential construction in New Zealand and can be used with NZS 4218:2009.
construction R-values must be taken from Appendix C of NZS 4218:2009.
Interpretation of NZS 4218:2009
This tool is implemented according to an interpretation of NZS 4218:2009.
BRANZ Ltd accepts no liability for loss or damages resulting from use of this tool. The accuracy of the calculation relies on the designer entering accurate
and truthful values.
Restrictions on use
This tool is only to be used in its full
More information on NZS 4218:2009 and NZBC clause H1
How to use the BRANZ NZS 4218:2009 Calculation Method
Open/print a PDF of these instructions
IMPORTANT: Only enter data or select options in unshaded
cells. Select options from a drop-down list in cells shaded light blue.
Set up the climate and building construction type:
- Go to the Project Summary
- Enter the details of the project name, addresses, designer etc. (This is for your own information only.)
- Select the climate zone from the drop-down
- Select the wall construction type from the drop-down list.
- If mixed construction (wall construction type option 4) selected, enter the percentages of
wall area (excluding glazing) of different types. The ‘Any wall type' percentage is automatically calculated. For example, if the design has 20% wall area solid timber, 30% wall area high
thermal mass and 50% other, type in ‘20' for solid timber and ‘30' for high thermal mass, and 50 is automatically calculated.
- If solid timber (wall construction type
option 2) selected, choose the wall construction details from the drop-down list.
B. Enter the areas and construction R-values for all building
- Go to the Building Elements worksheet.
- Enter details for roofs/ceilings, skylights, walls, floors,
vertical glazing and doors. (See NZS 4218:2009 for the definitions and measurement details of these building element areas.) For each building element, in the appropriate
- Enter a description for each part of the building element.
- For each part of the building element, enter the
- For each part of the building element, enter the construction R-value - a message is displayed if the R-value is too low. (Different parts of the same building element with
the same construction R-value may be combined into one area.)
- Check that:
- all parts of building elements are entered
individual and total areas match the plans
- the R-values are reasonable.
the Project Summary:
- Go to the Project Summary worksheet.
- Check that the climate zone and wall construction type
options are correct.
- Check that the design has <=40% glazing.
- Check that the minimum R-values are not too low.
- Check that the design
passes. (For wall construction type options 2, 3 and 4, a provisional pass may result as there are some issues that must be checked by the designer and
D. Save a copy of the spreadsheet for your design documentation - change the file name as
E. Print a copy of the spreadsheet for your consent documentation. Supply all printed sheets with the consent so everything can be
checked and include any relevant supplementary information.