Solar irradiation inside a single span greenhouse

Abstract

A model is offered through which the solar irradiation can be computed inside a single span hemicylindrical tunnel greenhouse. The model is mathematically exact. From the physical point of view it is founded on the assumption that the cladding surface is fully diffusive and that the radiation diffused through the atmosphere and by the ground is fully isotropic. It is found that the solar irradiation inside the greenhouse depends upon its orientation. A greenhouse with its longitudinal axis aligned along the north-south direction collects more radiation in summer and less in winter as compared with a greenhouse with its axis aligned along the east-west direction. On the other hand the east-west oriented greenhouse is more efficient in collecting solar radiation in winter than in summer, while the north-south oriented greenhouse exhibits a constant efficiency the year round. Finally, it is shown that the collected radiation depends upon the optical properties of the cladding surface being mainly determined by its transmittance.