I. Seginer
The optimization scheme outlined by Seginer (1980), was used to solve for the economically optimal environmental conditions in a greenhouse where carnations are grown. The growth function of Enoch and Sacks (1978), physical properties of well maintained glasshouses, and the price-system of New-York State in 1979, were used as input to the computer program.

The main results consist of the recommended inside temperatures as a function of the outside conditions. In particular was explored the effect of outside solar radiation and air temperature on the recommended inside temperature.

Analysis of the results indicates two clearly distinguishable regions:

  1. Unventilated greenhouse with heater and/or CO2 generator on.
  2. Ventilated greenhouse with fan and/or wet-pad on.

There is a discontinuity of inside temperature between these regions, and there is some shift of the boundary between the two regions as the optimal temperatures for plant growth are changed.

From the detailed results, certain overall engineering parameters could be estimated. The results for U, the overall heat transfer coefficient, and for a, the heating efficiency of solar radiation, were found to be conservative enough to be useful in engineering calculations. The Bowen-ratio (sensible to latent heat in ventilation), was found not to be a useful conservative entity.

Seginer, I. (1981). ECONOMIC GREENHOUSE TEMPERATURES. Acta Hortic. 115, 439-452
DOI: 10.17660/ActaHortic.1981.115.50

Acta Horticulturae