Building Enclosure Commissioning (BECx) (sometimes 'envelope' is used instead of 'enclosure') is a quality-focused process wherein the energy performance of a facility, system or assembly is evaluated and verified against defined objectives and criteria.
The process itself is carried out by a commissioning team which uses reliable and accurate measures to verify that the project is meeting specific quality requirements outlined by the owner of the project.
Once the construction is finished, the commissioning process continues and becomes an ongoing routine in the life of the facility.
Specific information regarding the commissioning process is outlined in the ASHRAE Guideline 0-2005: The Commissioning Process.
This and several other technical support guidelines to the Guideline 0-2005 document provide specific information related to the commissioning process.