The Window and Glazing Association of NZ (WGANZ) have developed some quick reference guides guides for pretty much all building types and a quick tool to figure out the R-values for climate zones and dates changes take effect.
To figure out the R-values
https://www.wganz.org.nz/h1-information-hub/?hilite=H1
The WGANZ Resource Directory is a handy place to find just about anything to do with windows.