PWS 1.5.7 specifically requires personnel performing HVAC work to have a current license in the state where the work is performed and to be certified through an approved pathway such as NATE, HVAC Excellence Professional Level, ICC, documented journeyman status through a recognized apprenticeship program, documented military Level Five or higher training, or other DoD equivalent. State licensing reference: Massachusetts - Refrigeration Technician LicensePWS source: Performance Work Statement OMEE - Northeast, 23 March 2026, 1.5.7 and 1.5.7.1, including specialty credential requirements applicable to refrigerants, BAS, TAB, backflow, gas piping, and welding.