Greenhouse Dehumidifier Calculator
Calculate commercial dehumidifier sizing in pints per day (PPD) and liters per day based on canopy transpiration rates and night humidity targets.
Controlling Night Moisture: The Greenhouse Dehumidifier Calculator
As evening sets in and greenhouse air temperatures drop, relative humidity rapidly climbs toward 100% saturation (dew point). High relative humidity leads to condensation on leaves and structure walls, creating ideal breeding grounds for destructive fungal diseases like Botrytis cinerea (gray mold). The greenhouse dehumidifier calculator (searched as greenhouse pints per day dehumidifier calculator, greenhouse humidity control calculator, or dehumidifier sizing greenhouse) sizes commercial moisture extraction systems in Pints Per Day (PPD) and Liters Per Day.
Calculating Canopy Transpiration Moisture Loads
Nearly all irrigation water applied to greenhouse benches evaporates into room air via plant transpiration. A mature crop canopy transpiring 0.10 gallons of water per square foot of bench area daily generates significant atmospheric moisture:
Daily Transpiration Gallons = Canopy Bench Area (sq ft) × 0.10 gal/sq ft
Required Dehumidifier Capacity (PPD) = Daily Transpiration Gallons × 8 Pints/Gallon
For a 500 sq ft bench canopy, plants transpire ~50 gallons of water daily, releasing 400 pints of water vapor into the air every 24 hours. Commercial overhead dehumidifiers must be installed to extract this moisture during unventilated nighttime hours.