Maximum Yield USA January 2017 | Page 68

CONTROL YOUR GROW “ Greenhouses take advantage of the daily photons available and the spectrum of the sun.” GREENHOUSES Depending on the amount of technology in the greenhouse, there can be great variance in production quality. This is usually due to the greenhouse effect and low insulation ratings that greatly test the building’s ability to maintain an artificial environment. For this reason, some consider greenhouses to be more like outdoor agriculture, but given the correct level of sophistication, greenhouses can outperform many indoor gardens. Although most greenhouses use the method of exchanging air from the outside world and moving it throughout the greenhouse, there are other technologies, such as positive pressure or enclosed greenhouses, in which air is not simply moved through the greenhouse, but rather captured and recaptured while being manipulated and controlled using various equipment and technologies. Most greenhouses use the former. As the air is pulled through the greenhouse, heat is removed in the process. As heat is removed, so is CO2 and humidity. In drier climates, greenhouses can easily be cooled by pulling air across saturated sponge-like pads on one end and with exhaust fans on the other. Another cooling method utilizing the evaporative cooling effect is highpressure misting in which the tiny fog-like droplets evaporate as they are moved throughout the greenhouse. 66 Maximum Yield USA  |  January 2017