Having just been through a training course on Energy Assessment, I can tell you that the EPC is just part of a Government-run scam to make it look like they're doing something to meet the EU "carbon footprint" target.
It's a worthless document full of advice that you could have figured out for yourself. The statistics are derived from nonsense measurements filtered through inadequate software, that serve no useful purpose.
On top of which, the "industry" (totally unregulated by the "Communities for Local Government" and it's quango offshoot) continues to take money from trainees when it has known since 2008 that the number of assessors needed has long since been over-supplied, to the extent that all those qualified since that date cannot find work and even those early qualifiers with contacts and a client base are just hanging on by their financial fingertips(but that's another story)… 👿