Protected Cultivation
Greenhouse Energy & Heat Balance
Protected structures gain, store, and lose heat through solar radiation, glazing, air exchange, equipment, crop transpiration, and outside weather; temperature control is therefore an energy-balance problem, not a thermostat-only problem.
Key concepts
- Solar gain can raise interior temperature rapidly even when outdoor air is mild
- Glazing material and structure geometry affect heat gain and loss
- Plants and wet surfaces add latent heat and water vapor to the air
- Ventilation, shade, evaporative cooling, heating, and dehumidification each change more than one environmental variable
What to measure or observe
- Log inside and outside temperature through the day
- Compare sunny and cloudy periods
- Identify hot zones near glazing or poor air mixing
- Record equipment operation alongside environmental changes
Common mistakes
- Treating air temperature as spatially uniform
- Adding cooling without checking humidity consequences
- Ignoring night heat loss and cold surfaces
- Using one sensor as the entire greenhouse
Visuals this lesson still needs
- Greenhouse heat-balance diagram
- Solar gain and heat-loss cross section
- Day/night temperature profile
- Sensor-location heat map