The exergy loss describes the exergy leaving the system as a waste stream, ∑𝐸𝑥 (,345,6 , and the cumulative exergy demand, 𝐶𝐸𝑥 7 , is the exergy which is used as input to the system, see Eq. ( ). The exergetic efficiency, η -8 see Eq. ( ), is the ratio of useful exergy outlet over exergy inlet.