Thin Glass: A Study on the Applicability in Greenhouse Coverings

Glass is a commonly used material for façades and roofs. Recently even structural glass elements have been developed and the application of glass in structural elements is becoming more common. The ongoing development of new glass types and different production and processing methods resulted in the manufacturing of thin chemically strengthened aluminosilicate glass by AGC. Thin glass is mainly applied in the electronics industry, but the increased strength, optical properties, toughness, bending resistance and weather resistance make it a promising material for application in buildings. The Netherlands is the globe’s number two food exporter and more than half of the nation’s land area is used for agriculture and horticulture. Research on the optimisation of greenhouse designs is a hot topic in the Netherlands to maintain this leading position. The greenhouse industry provides an appropriate application for flat thin glass panels, because of the possibility to increase both light transmittance and structural performance. The goal of the research presented in this report is to determine the feasibility of the application of thin chemically strengthened aluminosilicate glass in greenhouse coverings. The research was divided into four topics that are relevant for greenhouse designs: building physics, structural properties, structural behaviour and economics. The building physics research was conducted in collaboration with the Greenhouse Technology team of the Wageningen University & Research. The light transmittance results showed an increased hemispherical light transmittance for thin glass when compared to regular float glass. The investigation of the structural properties of thin chemically strengthened aluminosilicate glass was based on available literature and the material properties provided by the producer. For this research a characteristic bending tensile strength of 260 MPa has been assumed. However, further research is recommended for the determination of the accurate bending tensile strength and design impact strength of thin glass. The structural behaviour of a thin glass panel in a greenhouse covering was investigated by executing both numerical and experimental analyses. The numerical analysis of the reference system showed that it is necessary to stiffen the thin glass panel for flat application in a Venlo greenhouse system. Multiple variants were designed and studied by numerical and experimental analyses. The IGU panel turned out to be the most promising variant for future application of thin chemically strengthened aluminosilicate glass in greenhouse coverings. As a main outcome it was concluded that thin chemically strengthened aluminosilicate glass has a better light transmittance, higher bending strength and increased impact strength than regular float glass. This leads to a higher crop yield and lower costs for transportation, construction, maintenance and insurance which makes thin glass an attractive alternative. At this moment, however, the material costs are very high and the decreased thickness and increased flexibility resulted in a lower stiffness. It is therefore not likely that a single layer of uncoated thin chemically strengthened aluminosilicate glass will result in a feasible greenhouse covering design. Nevertheless, the use of thin chemically strengthened aluminosilicate glass can result in an optimised greenhouse covering design when applied as an insulating (IGU) panel.Civil Engineering | Building Engineerin