Ventilation and Cooling Systems

Some types of ventilation and cooling systems are:

1. Natural ventilation system - The air is exchanged through open ridge and side vents. This is one of the oldest methods of cooling. Note that injury to plants located near the side vents may occur.
   
   
2. Fan-tube ventilation system - The air is distributed through a plastic tube with holes that run the length of the greenhouse. This system, shown in Figure 13.9, is used in conjunction with the heating system.

Figure 13.9: Fan-tube Ventilation System

3. Fan and pad cooling system ( Figure 13.10) - This type of system is used for summer cooling.

Figure 13.10: Fan and Pad Cooling Systems

4. Fog evaporative cooling system - This system utilizes a fog generation system inside the greenhouse, which is similar to what you see when football players are cooled down on the sideline.

An alternative way to cool greenhouses is to use shading materials. Liquid shading compounds are often applied to glass as well as polyethylene covered greenhouses to reduce the light intensity as well as the temperature. This is typically done in the spring and summer. During times of the year when heat buildup is not a problem, this material is washed off to allow more light into the greenhouse.