Defining sustainability: Critical factors in sustainable material selection

Abstract

The designer is faced often with questions of material selection. To answer these, functional requirements must always be met, and second the cost constraints of the project must not be exceeded, and preferably they are minimized. Sadly, once the functional requirements are met, and the costs minimized, the selection process usually ends. By taking a life cycle analysis approach, the environmental impacts of a particular material can be assessed properly. If this were the third criterion, one could expect that environmental impacts like carbon emissions, energy requirements, and toxic emissions would all be minimized. But will these efforts result in sustainable material use? In this article we postulate that the additional question of whether a material can be recycled repeatedly without degradation, or cycled at a sustainable rate through nature (for example, by composting), is the most significant question to ask when assessing the sustainability of a particular material. Because economic considerations are often held paramount, it is common to select non-recyclable materials that are eventually discarded. These non-recyclable materials must be acquired as primary resources, and all the technologies required to obtain, process, and use these materials must be developed. When finally scarcity renders it economically prohibitive to extract, the effort and energy put into developing its use will have been wasted. This paper considers the long term life cycle cost of non-recyclable and recyclable materials. The results suggest that future designers avoid the use of non-recyclable materials in order to minimize environmental and economic cost over the long term.