In the present paper, a life cycle assessment (LCA) study regarding barley and lettuce production in Spain (Barrax and Santomera regions) and Italy (Albenga region) in both open field (OF) and standard greenhouse (GH) cultivations was performed in order to evaluate energy consumption and environmental impacts. The study examines also the impact of the use of compost produced from agricultural wastes (AW). In this context, a detailed life cycle directory was created, based on site-specific experimental data, and used for a holistic cradle-to-gate LCA analysis using the GaBi 6 software package and specific related databases. In order to reveal the importance of system boundaries, factors that are often excluded from LCA studies, such as agricultural machinery manufacture, nursery production, waste management and raw materials transportation have been considered.According to the results of this study, the use of compost for fertilization of both crops is considered a good agronomic and ecological strategy in order to maintain productivity in terms of yield, especially in the case of greenhouse cultivation, and improve overall sustainability in the agricultural sector. Moreover, the phases of compost production, irrigation system, and greenhouse construction and operation were identified as the three main “hot-spots” with the highest environmental impact and energy contribution in all studied cases. Finally, improvements to reduce those impacts were proposed