Here are two paragraphs from the French government site. (Please feel free to comment on my translation Alec in France).
Execution of these EPCs has been compulsory, at the time of sale of / on selling (“à l’ocasssion de la vente”) every accommodation or building (without exception) in metropolitan France, since 1 November 2006, and at the signature of renting contracts since 1 July 2007http://www.logement.gouv.fr/article.php ... ticle=5873
From these dates onwards, the results of these EPCs must also be held at the disposal, by the seller or lessor, to all buyer or renter candidates making the request, “dès la mise en vente” as from putting a building or part of it on the market or offering it for rent
The first paragraph is somewhat ambiguous on when the EPC must be done. The second states that the certificate must be present before the house is put on the market, so that's the one I go with. This doesn’t tally with my own experience, where the ‘diagnosis’ was carried out a couple of days before the actual sale. Hardly surprising right enough, we are talking about France here.
I’ve also been reading some pretty damning articles in the French press and on French blogs on the subject. It appears malfeasance is rife; many ‘diagnosers’ are hardly even competent; their ‘inspections’ are cursory; they work in cahoots with estate agents and solicitors, paying them part of the fee (loot) in exchange for recommendations, etc. This tallies perfectly.