Greenhouse Cooling Calculator
Calculate evaporative cooling pad square footage, water pump GPM, and dehumidifier daily pint removal capacity required to maintain optimal VPD.
Summer Microclimate Control: Greenhouse Cooling & Dehumidifier Calculator
When outdoor summer temperatures climb above 90°F (32°C), simple exhaust ventilation alone cannot keep internal greenhouse temperatures below plant stress thresholds. Evaporative cooling pad systems (wet pads) draw hot ambient air through damp cellulose media, utilizing latent heat of vaporization to lower air temperature by 10°F to 25°F. However, added moisture raises relative humidity, requiring precise moisture removal sizing. Our greenhouse cooling calculations tool handles wet pad area, water flow GPM, and dehumidifier pint capacities.
Evaporative Pad Area Sizing Formula
Pad area ($A_{pad}$) depends on overall fan exhaust CFM and recommended air face velocity through the pad media:
Pad Area (sq ft) = Total Fan CFM / Recommended Face Velocity (FPM)
- 4-inch Thick Cellulose Pad: Design for 250 FPM face velocity.
- 6-inch Thick Cellulose Pad: Design for 350 FPM face velocity.
Dehumidification Pints Per Day Removal
During warm nights when exhaust fans turn off to conserve heat, transpirational water vapor from crop canopies rapidly drives humidity to 95%+, causing dew-point condensation. Calculate required commercial dehumidifier removal rate in Pints Per Day (PPD):
Pints / Day = Total Canopy Square Feet × Plant Transpiration Factor (0.08 - 0.12 Gal/sq ft/day) × 8 Pints/Gal