Domestic Energy Assessor (DEA) is the name given to professionals who can produce EPCs for existing dwellings, other than Home Inspectors.
A fully qualified DEA requires two things:
A Level 3 Diploma in Domestic Energy Assessment
To be a member of an approved accreditation scheme
To join an approved accreditation scheme you have to pass a series of background checks, including a Basic Level Criminal Records Bureau check.
EPC Services only employ fully qualified Domestic Energy Assessors.