Towards Unbiased Environmental Material Selection for a Structure - Case Study of a Navigation Lock Gate

This paper presents a few relatively simple and transparent methods of material selection for a civil engineering structure in view of sustainability. It is addressed to practicing engineers, designers, production managers, other professionals and students intending to take account of sustainability when choosing the material for new structures or maintaining the existing structures. The presented methods are illustrated by a case study for a navigation lock gate. The materials that are currently applicable for this structure are: structural steel, stainless steel, aluminum, polymer composite, reinforced concrete and timber. Three most common sustainability criteria have been considered, which are: 1. Energy use, 2. Loads (pollutions) to the environment, 3. CO<sub>2</sub> emissions (called also “carbon footprint”). In the current engineering practice, sustainability criteria and the related material choices are often prone to emotional reactions and driven by politicized or biased arguments. This paper aims to help engineers deal with this issue by focusing on verifiable aspects of sustainable construction. An attempt has been made to encourage critical approach and corrections in available databases for a better mach with the analyzed projects. The analysis covers the so-called “cradle to grave” life cycle, with some focus on manufacturing – the process that usually gives the highest environmental impact. The impact of less essential or less determined processes has been approximated, based on the authors’ experience in design and management of hydraulic structures. In order to quantify the required materials, conceptual designs of the lock gate have been developed in all materials. The structure type and sizes represent the medium-range of lock gate applications, which allows for general conclusions. Such conclusions must, however, take specific technological and other feasibility restraints into account.