THEORY AND VALIDATION OF A LIQUID RADIATION FILTER GREENHOUSE SIMULATION FOR PERFORMANCE PREDICTION
A greenhouse is described which has a selectively absorbing liquid radiation filter (LRF) circulating in double 
layered cladding. The filter removes much of the near infrared wave band of solar radiation (>700 nm) while transmitting 
most of the photosynthetic radiation (400-700 nm). This greatly reduces the heat input to the greenhouse and, by 
transferring heat from day to night, facilitates better temperature control. This is particularly important for CO2 
fertilization, which requires that the greenhouse should remain closed during daylight hours. 
A computer simulation model was developed to study the relationship between design parameters of such a LRF 
greenhouse and its thermal performance under different climatic conditions. The model was based on a small number of 
governing equations describing the major physical phenomena responsible for the greenhouse climate. Validation of the 
simulation was performed with data from a 330 m2 LRF greenhouse, operating in the Negev (Israel) desert highlands. 
The predicted greenhouse temperatures were found to agree with measured values to within one to two degrees Celsius. 
Performances of a LRF and a conventional greenhouse were compared using the simulation and hourly meteorological 
data for central Israel. For the summer season of May to October, the number of daylight hours during which the LRF 
greenhouse could remain closed was larger by about two-thirds than that of the conventional greenhouse.