A
computer simulation mo
del for natural ventilation in open
-
roof greenhouses was developed
to
predict the ventilation performance. The model predicts ventilation rate and the temperature
differences between inside and outside, based on the weather and structural conditions
includ
ing internal net radiation, wind velocity, and height and area of the roof openings. The
ventilation rate was calculated from thermal buoyancy and wind forces. A sensible heat balance
was incorporated to calculate the ventilation rate and the temperature d
ifference
simultaneously
.
A four
-
span open
-
roof greenhouse with roof sections hinging at the gutters and opening at the
ridge, constructed on the Rutgers University campus, was used for data collection.
Measurements of climate conditions in the direct vici
nity of the greenhouse were conducted.
Using the observed outdoor and greenhouse conditions, the model parameters were calibrated
statistically. The accuracy of the model and the modifications to the model are discussed by
comparing the predicted and obser
ved greenhouse temperatures. It is shown that the internal
temperature rise depends on the roof configuration as well as solar radiation and wind velocity.
The resulting simulation model can be used to implement new environment control strategies for
open
-
roof greenhouses