DETERMINATION OF DIRECT TRANSMISSION OF A MULTISPAN GREENHOUSE USING VECTOR ALGEBRA

The transmission of a multispan infinite greenhouse cover for direct radiation is calculated as a function of greenhouse geometry and solar position. The calculation allows for the shading effect of the main construction elements. The solution method is based on vector algebra. It appears that the use of vectors that denote the orientation of the planes in the greenhouse cover leads to a clear, and easy to understand calculation scheme. Therefore, the method presented here can be applied to other situations as well. Due to the compact and unambiguous notation, and assuming the availability of software suitable for vector algebra, programming effort is considerably diminished. The results of the solution method are compared with the model of Bot, which employs similar assumptions, but based on goniometric expressions. Calculations were made for the direct transmissivity of a venlo-type greenhouse and similar results were obtained. © 1993 Silsoe Research Institute.