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Abstract-A novel method is presented for the design of heat exchanger networks. The method is the first to combine sufficient simplicity to be used by hand with near certainty to identify “best ” designs, even for large problems. “Best ” designs feature the highest degree of energy recovery possible with a given number of capital items. Moreover, they feature network patterns required for good controllability, plant layout, intrinsic safety, etc. SCOPE Heat exchanger network (HEN) design is a key aspect of chemical process design. Typically, 20-30 % energy savings, coupled with capital savings, can be realised in state-of-the-art flowsheets by improved HEN design [ 121. The task involves the placement of process and utility heat exchangers to heat and cool process streams from specified supply to specified target tem-peratures. The objective is to minim & total costs, i.e. capital and operating costs expressed as annua