Professional engineering organisation IChemE has published a good practice guide to energy and resource efficiency. It was published by the IChemE Energy Centre, established in 2015.

The 28-page free document, available from the link below, presents 10 principles underlying an efficiency improvement project in process plants.
"As chemical engineers, we are uniquely placed to act in some of the most energy and resource intensive industries to reduce the impact we are having on the life support systems of our single shared planet,” says Mark Apsey, energy and resource efficiency task group lead, in the introduction.