Parametric analysis of greenhouse design for hydroponic barley cultivation: a case study in sustainable agriculture in arid regions

In greenhouse energy studies, particularly in hydroponic systems, many studies focus on a single aspect. However, a systemic approach and passive measures are often lacking, despite the need to consider the interactions between climate, energy, ventilation, solar gains, the building envelope, orientation, crops, and control strategies. The development of simulation models based on the proposed mathematical models significantly strengthens the novelty and relevance of this work. The main objective of this study is to maximize solar energy gains in a hydroponic greenhouse through strategic orientation optimization, thereby improving thermal performance and reducing operating costs. In controlled-environment agriculture, maintaining an optimal microclimate is energy-intensive; however, passive design remains an underused tool. This research uses mathematical modeling and the solution of energy equations to calculate the daily solar flux across various greenhouse orientations. Focusing on hydroponic barley cultivation, the study compares the thermal efficiency of an optimized glazed greenhouse with that of standard sandwich panel configurations. The results identify the south-facing orientation as the most effective passive design strategy for maximizing natural light and heat accumulation. Unlike residential buildings, heat losses due to ventilation account for at least 67.57% of total heat losses. Cooling requirements are more dominant, accounting for between 63.55% and 70.33%, depending on the type of window. The integration of double-glazed windows could prove beneficial, making it possible to achieve annual savings of 5.50% compared with a standard sandwich-panel wall without windows. Consequently, it appears more advantageous to exploit this solar potential for natural lighting rather than relying on artificial lighting. At present, barley producers allocate between 24.25% and 29.38% of their energy expenditures to heating, depending on the orientation of the greenhouse. By prioritizing natural solar gains over artificial energy inputs, this work provides a replicable framework for designing low-carbon food production systems. The findings serve as a robust case study for sustainable agriculture, offering practical insights for engineers and growers to improve the energy efficiency of greenhouse structures under similar climatic conditions.