Life Cycle Assessment of the production phase of Switchable Glass
Tutor / director / evaluatorHaase, Walter
Document typeMaster thesis (pre-Bologna period)
Rights accessRestricted access - confidentiality agreement
Switchable glazing systems for architectural application have been developed by modifying conventional Liquid Crystal technologies for Liquid Crystal Displays industry. They provide shade and visual welfare, improving users comfort without obstructing view to exterior. With its use, requirements for cooling in buildings can be reduced, what involves a contribution to sustainable building. The system is composed by to glass sheets (treated and coated with different layers), which contain inside the elements of liquid crystal and other needed elements. No environmental assessment has been made for the switchable element. The purpose of this paper is to assess the environmental impact of the production phase of switchable glass. This work is based on Life Cycle Assessment method within the frameworks of ISO 14040 and ISO 140444. The tool used to create and model Life Cycle Inventory and to analyse the result balances is the software GaBi 4 developed by Universtät Stuttgart. The production of the glass substrate is the process with most impact in all impact categories: Acidification Potential (AP), Eutriphication Potential (EP), Global Warming Potential (GWP), Ozone Depletion Potential (ODP), and Primary Energy Demand from Non Renewable Resources (PENREG), except for Photochemical Ozone Creation Potential (POCP). This is caused as result of the fact that the glass substrate is more than 99% of the mass of the whole switchable glazing element, and its manufacture has high energy consumption requirements (extraction of raw materials and melting processes principally). Most of POCP impact is due to solvent evaporation during the liquid crystal filling. Waste treatment for the water used to clean the substrates is also significant in most of the impact categories. This work can be used to compare different production systems for elements with the same function and it is the basis for further to analyse the whole life cycle of this glass, including use phase and end of life analysis as next steps.
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