Life cycle assessment of flat glass and the implications of thinner and stronger glass

Abstract: In the production of glass, the addition of more cullet to the batch of glass and the reduction of the thickness of glass are means to reduce energy consumption and raw material usage. This contributes towards improved energy efficiency targets of the European Union. This thesis investigated the energy consumed for the process of strengthening thinner glass as well the environmental implications of thinner and stronger compared to conventional glass across the life cycle of glass. The life cycle phases also included a recycling phase where 70% of the used glass was recycled with the remaining 30% being landfilled. The functional unit selected for this study was 1m2 of SLS glass, 4mm thick, with an average light transmittance of 91%. This corresponds to 10kg of clear float glass as per general rule. The findings of this thesis showed that one of the major contributing factors to high energy consumption in the melting phase of SLS glass is low efficiency of the furnace; this led to significant energy losses in the production of SLS glass. Recycling of flat glass, at a 70% rate, led to a 12% reduction in total global warming potential, a 10% reduction in the Acidification Potential, a 13% reduction in the Eutrophication Potential in marine environs, and a 7% reduction in the Eutrophication Potential in terrestrial habitats. The chemical and thermal strengthening process consumed 2.24 and 2.37 kWh/m2 respectively. The consequential impact of this is dependent on the source of the electricity for the strengthening processes. It was concluded that the energy used for the strengthening of the thinner glass is considerably less than the energy used in the production of a conventional glass that satisfies the same strength parameters.