Do I need a 24 hour fan-aspirated radiation shield?

It depends on your site. For most locations in New Zealand, nature kindly assists with this, with plentiful winds, so a standard radiation shield is enough.

The purpose of the 24 hour fan-aspirated radiation shield (FARS) unit is to regulate the sensor readings and maximise the sensor accuracy by circulating the air in the radiation shield around the temperature/humidity sensor. The FARS unit has a battery powered fan to do this.

A FARS unit on your ISS can be a great piece of kit for situations where there is little wind and the temperature reading is important, such as inside a shelter belt on an orchard where there is little wind and lots of sun.

The wireless Vantage Pro 2 sensor suites and weather station bundles give you the choice between a standard radiation shield or FARS option.