A Comprehensive Mathematical Model for the Estimation of Solar Radiation and Comparative Analysis in Greenhouses with Two Distinct Geometries and Covering Materials: Case Study in Psachna, Evia, Greece

This study calculates the intensity of radiation received by two types of greenhouses: Even Span and Modified Arched geometry. The Even Span greenhouse is covered with glass, while the Modified Arched greenhouse is covered with polyethylene plastic sheets. Both greenhouses are located in the same geographical area. The analysis incorporates various forms of radiation, including incident, reflected, transmitted, and absorbed radiation, calculated based on solar angles. Notably, this study does not include temperature data. The greenhouse covering material is considered transparent, and parameters such as the refractive index and the attenuation coefficient of the materials are integrated into the calculations. The integration of these specific indices allows for the calculation of radiation across different materials. Additionally, this study assesses radiation for all sides of the greenhouse, rather than focusing solely on the roof. The research analyses data from a total of 396 days, with measurements taken every ten minutes from a meteorological station situated near the greenhouses. MATLAB (R2021b) software is utilised for computational purposes to solve the relevant equations, while IBM SPSS Statistics 28.0.0.0 software is employed for statistical analysis of the results. The statistical analysis regards data collected from sunrise to sunset, varying by month. It is important to note that radiation values recorded with a negative sign are retained in this analysis, as they are considered useful for capturing the temporal and spatial dynamics of radiation within the model. The analysed greenhouses are geographically situated in the Psachna area of Messapia, Evia Prefecture, Greece.