What is a Frost Protection Score?

The Frost Protection Score (FPS) serves as a metric for evaluating the effectiveness of frost protection measures. It operates under the assumption that crop damage begins when temperatures dip 1°C below the fan start temperature, termed the critical temperature. During a frost event, the FPS computes the average temperature differential between actual readings and the critical temperature while fans are in operation.

Furthermore, it incorporates a correction factor based on the duration the crop remains below the critical temperature. It is assumed, that if the crop remains more than 60 minutes at or below the critical temperature, the crop will be severely damaged. We recognise that this might vary between crop types and time of the season, therefore it can be seen more as a generalisation.

Moreover, it integrates two correction factors:

1. AverageCriticalScore (ACS): This factor represents the average duration the crop remains below the critical temperature, calculated as the total time recorded below the critical temperature in minutes divided by the number of fans and converted to hours (60 minutes).

2. MaxImpactScore (MIS): This factor accounts for the maximum duration a single fan operates below the critical temperature converted to hours (60 minutes), adjusted by subtracting the AverageCriticalScore and dividing by the number of fans.

The FPS is subsequently determined by the formula:

FPS=(AverageTemp−CriticalTemp)−ACS−MIS

Here, AverageTemp denotes the average temperature during the frost event while the fans have been running. A FPS score of 1 or greater indicates a light event, suggesting effective maintenance of temperatures at or above the start temperature by the fans. Conversely, a score below 0 signifies a heavy event, indicating potential crop damage due to insufficient protection.