Calculate required ventilation rate and duration based on greenhouse volume, temperature difference, and target humidity.
Calculate greenhouse ventilation rate, air changes per hour, and recommended ventilation duration based on greenhouse volume, temperature difference, and humidity. Input floor area, height, inside/outside temperature and humidity, and vent opening area. Prevent overheating and high humidity that cause disease.
You closed your greenhouse vents at 6 PM to retain heat overnight. By 8 AM, humidity was 95% and temperature was 22°C — perfect for botrytis. You opened vents at 9 AM, but by then gray mold had already infected 15% of your strawberry flowers. The critical window was 6-8 AM, when humidity peaks and temperature rises. Ventilating for just 15 minutes at dawn would have prevented the outbreak. Humidity management is more important than heat retention in most greenhouses.
Enter greenhouse length, width, height (meters), outside and inside temperature (°C), outside and inside relative humidity (%), and available vent area (m²). Click calculate to see air exchange rate, ventilation capacity needed, required fan capacity, and humidity control assessment.
The greenhouse ventilation calculator helps you design an effective ventilation system to maintain optimal temperature and humidity for your crops. It calculates required ventilation rates, fan capacity, and vent area based on greenhouse dimensions, temperature differences, and humidity levels.
A: Most vegetables grow best at 20-28°C during the day and 15-18°C at night. Tomatoes prefer 20-25°C day/16-18°C night, cucumbers 22-28°C/18-20°C, lettuce 15-20°C/10-12°C. Temperatures above 30°C reduce photosynthesis and increase disease risk. Ventilation is critical to prevent overheating.
A: A general rule is 0.5-1 cubic meter per minute per square meter of floor area (or 1-2 air changes per minute during peak sun). For fan ventilation: 1 cfm per square foot of floor area (0.5 m³/min per m²). Larger greenhouses and hot climates need higher rates. Combine natural ventilation (roof vents) with fans for best results.
A: Maintain relative humidity between 50-70% for most crops. High humidity (>85%) promotes fungal diseases (botrytis, powdery mildew). Control humidity through: ventilation (exchange moist air with dry outside air), heating (warm air holds more moisture), proper plant spacing, and avoiding overhead irrigation in the evening. Dehumidifiers are an option in closed greenhouses.