Global markets have been facing an increasing competitiveness, leading to a dramatic intensification of the market pressures in terms of business sustainability. Businesses, through their industrial processes, urgently require retrofit actions for improving their sustainability performance. Therefore metrics intended to measure sustainability are critical to assess new retrofit designs. This chapter intends to present a literature review on the areas of improvement that should be assessed in sustainable retrofit design decisions. The most relevant areas of assessment of economic, environmental, and social aspects are identified and classified according to the retrofit actions undertaken. This classification suggests that different levels of detail are required for the analysis of retrofit designs, spanning from operational-level assessment to supply chain-level evaluation. A framework, called strategic sustainable assessment of retrofit design, is proposed to guide decision makers in their retrofit design sustainability assessment. The framework is highlighted through a case study of β-galactosidase production.