Environmental & Climate

Environmental Control

Control sizing and system recommendations for grow environments.

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What it does

An HVAC sizing calculator that estimates sensible and latent heat loads, equipment capacities, daily energy use and VPD for a grow room. It also has a tomato-only P-Band climate control section and exports a PDF report.

When to use it

Use it to size cooling, heating and dehumidification for a room from its size, lighting power, plant transpiration and outdoor conditions.

How it calculates

Lighting sensible heat = lighting power × (1 − LED efficiency ÷ 4.6 μmol/J), plus 10% for other sources such as ballasts, fans and people
External gain = floor area × (outside temp − target temp) × 5 W/m²/°C; latent heat = transpiration (kg/h) × 2260 kJ/kg
Cooling capacity = total heat load × safety factor; heating capacity = 0.7 × cooling capacity
VPD = saturation vapor pressure 0.611·exp(17.27T/(T+237.3)) × (1 − RH/100), compared with a crop-type target VPD

What you enter

Width, Length, Height(m or ft)
Total Lighting Power(W)
LED Efficiency(μmol/J)
Operating Hours/Day
Temperature(°C or °F)
Humidity(%)
Crop Type
Plant Density(plants/m² or plants/ft²)
Transpiration Rate(L/m²/day or gal/ft²/day)
Outside temperature and humidity, and safety factor

What you get

Total, Sensible and Latent Heat(kW)
Cooling and Heating Capacity(kW)
Dehumidification(L/day)
Air Changes
Daily Energy: Cooling, Heating, Fan(kWh)
Energy Intensity(kWh/m²/day)
Optimal VPD, deviation, and humidity and temperature adjustment
Summer and winter peak (kW) and carbon footprint (tons CO₂/year)

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