Porirua City has one official sundial.
Sundials need to be precisely designed for each location, which is why the mass produced sundials are never accurate. All sundials measure "daytime" based on the sun which varies from "clock time". This is due to the variations in the earth's orbit. This difference varies over the year but is easily calculated by the equation of time located by the right side of the sundial which gives the variations.
The sundial was designed by Andrew Gray and manufactured by A E Tilleys Ltd and John Kinviq Engineering and installed by Gavin Dench.
Location – Corner of Parumoana and Norrie Street, Porirua CBD
Link to more information
Further information and how to build your own sundial can be found on the Sundials