This guidance document provides an application guide on how to utilize ASME EA-1, Energy Assessment for Process Heating Systems. This guidance document provides background and supporting information to assist in applying the Standard. ASME EA-1 does not provide guidance on how to perform a process heating energy efficiency assessment, but sets the requirements that must be performed during such an assessment. ASME EA-1 was written in a form suitable for a standard, with concise text and without examples or explanations. This document was developed to be used in conjunction with the standard to give basic guidance on how to fulfill the requirements of the standard. This document is only a guide and does not set any new requirements. ASME EA-1 can be used with or without this document.