2.3.1.6.2 Natural Ventilation Systems
Natural ventilation systems, are systems that work manually or through natural energy. They are
normally windows or roof tops which optimizes the exchange of air inside the greenhouse.
A good automated option would a solar-powered vent opener, this solar vent converts the heat energy
into mechanical energy to open the vent. The higher the temperature the wider the vents will open. This
occurs in the black cylinder, power tube, in the image below, it contains a mineral inside that expands
when heated and shrinks when cooled. The expansion of the mineral pushes the piston, which drives the
vent up.
Figure 18: Solar-powered vent opener
The table below represents the characteristics of the solar-powered vent opener show in the figure
above. The cost of the whole system is $69.95 according to FarmTek, and although the power tube and
the spring need to be change from time to time, they are only a fraction of the total cost of the system.
Solar-Powered Vent Opener
Allows solar-powered control of either top or side
mounted window vents.- Adjustable opening temperature of 60°F to
75°F, and an 18" maximum opening. - Soundless wax motor reacts to solar sensors,
opening vent just enough, allowing for a quieter,
relaxing environment. - Works independent of power grid to
continuously monitor greenhouse temperature. - Recommended for use in temperatures up to
120°F. - Lifting capacity: 15 lbs.
- It is recommended the vent cylinder be
removed during the winter months.
Costs $69.95 on FarmTek(FarmTek, n.d.)
During the interview with Abbie White, from WPI’s greenhouse, she mentioned that automated system
during the winter can be extremely inefficient because they open when the inside is hot, letting all the