**2. Circular economy and the built environment**

The primary objective of circular economy is to change materials use from the linear model to the circular model. The linear model is a straight-line flow of materials from extraction of raw materials to product use and ultimate disposal to landfill or through incineration at the end of the product life cycle. The circular model promotes use and reuse of materials, through a process usually referred to as "closing the resource loop." In addition to closing the resource loop, circular strategies can also lead to "narrowing" or "slowing" of resource loops thereby improving the efficiency of processes and extending the lifespans of products [17].
