A Hybrid greenhouse utilizes the design concept of a Positive Pressure Greenhouse but adds one additional and very useful item, air conditioning. Hybrid greenhouses can utilize dehumidifiers, chillers, coolers, or traditional HVAC. This allows the grower to use the greenhouse as a traditional greenhouse most months of the year, utilizing outside air. During those months when the air is too hot, or more likely, too humid, the outside vents close and instead of pulling outside air into the greenhouse, chillers or air conditioners scrub the air free of humidity, mold, pollen, spores and of course lower the temperature.
This cold air is then pumped into the cooling chamber where it is pulled into the greenhouse and distributed through the ducts under the crop's root structure and is forced through the canopy. During this period, the greenhouse remains closed, and the air is returned back to the cooling chamber to be scrubbed of humidity, and heat and then pumped back into the greenhouse. While this offers incredible control and the most ideal environment, the utility expense during this period can be 10 times or more expensive than the traditional positive pressure method of cooling a greenhouse through evaporation of outside ambient air temperature. Many growers will argue that this is the best option available today giving them the ability to utilize many different environmental control options as the seasons change to make their operation as efficient as possible.