Table 3

Derived parameters from gathered data. The timestep column indicates the resolution (hourly, daily, bi-daily, monthly)

Derived parameter (unit)TimestepCalculation methodology
Temperature in the tunnel (°C)Hourly Daily: night 1am and day 1pmTaken as the weighted average by location of the temperature sensors in the farm
Relative humidity – Acceptable conditions [0 – 1]HourlyTaken as proportion to acceptable level [45%-65%]
Air mixing (horizontal and vertical)HourlyFrom horizontal and vertical stratification of temperature
Air velocityHourlyAverage (including calibration correction for low air velocities), looked at in combination with door status (open/ closed) and ventilation setting
Air change rate (h-1)DailyDifference between the max and min CO2 level in the day
Length of photo-period (-)DailyDerived from energy use (time of energy use change – only since hourly metering, period was constant at 18hours)
Outdoor temperature (°C), relative humidity (%)Hourly and Night/Day differentiationMeasured hourly, and average night-time/daytime (corresponding to photoperiod)
Precipitation (mm) & relative humidity (%)Hourly (+1, +2, +3 hours, +12 hours, + 1 day) and DailyCorrelation window is analysed with delay
Percentage of occupied area of farm (%)DailyDisaggregation of harvest data in between date underlights and harvested, taken as proportion of farm with increasing farmed area.
Yield performance of three main and sufficiently representative crops: peashoots, wasabi mustard and salad rocket (-)DailyTaken as the eventual yield performance of each crop, for a given day. Yield is calculated by (mass harvested + surplus)/area [g/m2]. Yield performance is taken against the average yield of that crop.
Growing days of crop (-)DailyTaken as eventual (number of growing days)/(average number of growing days for crop)
Energy use (kWh)Daily, MonthlySum of metred energy use, as fraction of capacity
Water use (L)Daily, MonthlyDisaggregated water quantity filled in water tanks by calendar day
Crops (g/m2)Daily, MonthlyQuantity grown per calendar month
Crop health (%)DailyPercentage lost to crop disease

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