Energy Assessments (EPCs) and holiday lets

As from 1 October new build houses and houses being rented out need to have an Energy Performance Certificate.

Fortunately, it seems that holiday lets do not need to have a certificate, unless they are rented out to the same person for more than 3 months.

There doesn't seem to be an official site stating this but here are 3 assessment firms that think this is the case:

http://www.cdmmuk.co.uk/domestic_energy_performance_certificates.htm

http://dolphin-epc.co.uk/page_1203968258456.html

http://www.energyassessorlincs.co.uk/landlord_epc.htm

If anyone knows an official site that confirms this please post a link in a comment.