Articles
GREENHOUSE COVERS: HEAT REQUIREMENT AND INSOLATION
Double layer air-inflated polyethylene film required 25 percent less heat than the greenhouses covered with new corrugated fiberglass reinforced plastic panels, single layer polyethylene film and 8 year old fiberglass reinforced plastic panels during nocturnal periods.
Outside temperature and wind speed accounted for more than 85 percent of the variability in the heat requirements and were linearly related to the heat requirements.
Double layer polyethylene was most efficient in heat conservation with respect to wind.
The heat requirement during daylight periods was substantially less for double layer polyethylene.
Insolation and outside temperature accounted for over 80 percent of the variability in the heat requirements and were interrelated.
Percent transmitted insolation was highest in the new fiberglass treatment and lowest in the old fiberglass treatment thus directly influencing the fuel required for daytime heating.
The greatest number of carnation flowers were produced in the single layer polyethylene greenhouse, but peak flower production periods were slightly delayed compared to the new fiberglass treatment.
No prominent production peaks were noted in the old fiberglass treatment and 55 percent fewer flowers were produced compared to the new fiberglass treatment.
Production of carnations in the double layer polyethylene treatment was reduced 20 percent compared to new fiberglass, offsetting the overall fuel use reduction of 26 percent.