How do you approach retrofitting an existing heat exchanger network to reduce energy consumption?

Retrofit methodology: perform data reconciliation on existing network, construct grand composite curve to identify energy targets, compare current consumption to targets to quantify savings potential. Modifications ranked by cost-effectiveness: adjust operating conditions (flows, temperatures), enhance existing exchangers (inserts, retubing), add new area to existing shells, resequence existing exchangers, and add new exchangers. Constraints include: existing plot layout, piping modifications cost, shutdown duration, and operability impacts. Payback under 2 years typically required for approval.