Greenhouse Air & Heat Dispersion

[Millet]

My greenhouse is 32 feet wide, 72 feet long and 11.5 feet high.  To insure equal dispersion of heat and air movement to all sections of the greenhouse, I use fans.  Because heat raises there are three 20-inch fans hanging from the ceiling 10 feet from each end and one in the middle of the greenhouse to blow the heat back down to the plants.  Additionally, three 20 inch fans are setting three feet above the floor moving air horizontally around the greenhouse.   The ceiling fans perform twp functions.  First, as stated they move air from the roof back down to the level of the plants, and second they reduce the temperature differential between the inside ceiling covering and the outside cold air.  The greater the differential between the two, the faster heat is lost to the outside.  By blowing the hot air back down to the floor, the heat gradient is reduces and therefore less heat is lost.         

[Citradia]

Millet, you have electric heaters in greenhouse too, no?  Is less overall electricity used when using fans as described, as opposed to just using electric heaters on thermostat?  Or maybe you use oil heaters?

[Millet]

The greenhouse is heated by two overhead large propane heaters.  One set at a higher temperature than the backup one.  So if one heater should beak down or fail to ignite, then the backup heater will take over.  It would be very rare that two heaters should break down on the same night. The trees like the air movement, which also eliminates any cold spots.  It also evenly distributes all the available CO2.