Modeling the use of transportation energy for recycling construction steel

Recycling of construction and demolition waste (CDW) is a de facto criterion for most green building rating systems. However, research has found that CDW recycling increases the energy embodied in recycled materials. Even though CDW recycling reduces the demand for virgin materials and landfill space, several studies have concluded that the energy footprint of CDW recycling can be significant. Previous studies have found that the amount of energy needed to recycle CDW is driven by many factors, including regional recycling capabilities, distances from construction sites to recycling facilities, and the types of recycling facilities. The purpose of this article is to present a transportation energy accounting method, using material flow analysis, whereby designers and contractors can (1) reliably and easily estimate the transportation energy use at the design and construction stages, and (2) reduce the number of assumptions and thereby improve the reliability of the models.