Geometric Analysis of Greenhouse Roofs for Energy Efficiency Optimization and Condensation Drip Reduction

Abstract

Greenhouses are instrumental in the advancement of regions globally. The geometric arrangement of these structures plays a pivotal role in governing sunlight distribution, facilitating ventilation, and managing condensation. The roof’s shape significantly affects energy efficiency and the accumulation of condensation water, which, when dripping onto crops, can induce diseases and diminish production. This study introduces a Matlab program designed for defining and analyzing greenhouse roof geometry that is adaptable to both single-span and multispan structures. Various roof shapes were examined, and angles along their length were determined to facilitate condensation droplet runoff. In the ogival roof shape, water droplets adhering to the roof surface were found to slide off, preventing interior dripping. However, in all semicylindrical roof structures, dripping occurred on more than 50% of the cultivated ground surface. Furthermore, the greenhouse’s energy efficiency was evaluated by analyzing diverse roof models, accounting for the surface area and internal air volume. There was little difference in the volume of air inside the greenhouse attributable to the roof shape. Increasing the arch height relative to the span width enhanced solar energy capture and the roof surface, with the semicylindrical shape being more efficient in this case. The results aim to aid in the selection of the optimal greenhouse type based on the climate and latitude. This study offers a valuable decision-making tool for the planning and design of agricultural structures, providing insights to enhance their overall sustainability and performance in diverse environmental contexts. Hence, in cold climates and high latitudes, the steeper roof angle of the ogival shape type 2l and its smaller surface area promote solar energy capture and reduce convective heat losses. In warmer climates, a larger roof surface facilitates natural cooling, making the ogival shape type 3l/2 recommended.