Evaluation of a plastic tube based hydroponic system for horizontal and vertical green surfaces on buildings

As the urban population expands and more people around the world live in dense aggregations, the necessity for green spaces or just more vegetation in cities is of great importance. Plants contribute significantly to most projects and policies aimed at tackling urban environmental problems as well as to physical and psychological health of citizens. The development of alternative hydroponic structures placed above the ground for planting ornamentals and vegetables might be an efficient means to improve the urban environment as the available open spaces are often limited. These systems can form green surfaces of various slopes in contact or in a distance from buildings. In this framework, properly formed plastic tubes were used as plant containers for construction of horizontal (pergolas) and vertical (panels) via closed-loop hydroponic systems. Two different nutrient solution, closed-loop hydroponic systems were evaluated for their suitability to support a hydroponic pergola. The structural parameters (design, materials, hydroponic system support and function, etc.) are presented along with results regarding nutrient solutions parameters, substrate parameters and microclimatic effects. The latest results were compared with 3 years of average data from the same site, before the installation of the hydroponic structures. The results show that such structures are feasible, easy to operate and maintain, positively affect the surrounding microclimate and provide significant aesthetical improvements in urban areas.