This paper describes the basic idea of Material Flow Cost Accounting (MFCA) and explores its usefulness for environmental and life cycle engineering. It argues that a better understanding and assessment of costs related to waste flows incentivizes engineers as well as managers to constantly increase resource and energy efficiency. The paper proceeds to explore MFCA beyond its current methodological limitations by highlighting its potential benefits for life cycle and carbon footprint assessments as well as its usefulness for assessing the financial and environmental consequences of material flow loops in production.