A 
system, methods, and user-friendly program product to optimize 
energy recovery for a process or cluster of processes under all possible combinations of given 
process changes and 
stream-specific minimum temperature approach values without enumeration, are provided. The systems, methods, and program product can include steps / operations to identify an optimal set of discrete target temperature values for the process streams for a given 
heat exchanger network design, to identify which target temperature values of the various process streams have the most significant economic 
impact on the process or cluster of processes, and to identify process 
stream supply attribute ranges of variations, e.g., in the form of a criticality 
list for the plurality of process streams, e.g., resulting from disturbances and / or uncertainty, which have a highly significant or otherwise critical effect on streams target temperature.