It has been a legal requirement for all rentals from Oct 2008 to have a valid EPC.  They currently lasts 10 years but would only need to be renewed (on expiry) upon change of tenure – i.e. sale of property or new tenant; there is no need to get a new one whilst a tenant is still in occupation.
They must be ordered prior to marketing, and there is a penalty £200 per breach for not having one.
All marketing material must show the rating, and it must be available to show any potential tenant.
A rating of F or G could be deemed to be cat 1 HHSRS hazard, and you now cannot issue new AST for an F or G rating, or continue with an existing let (see MEES below).

EPC checklist:-
An assessor will check the following:-

• Age and efficiency of boiler;
• TRV ‘s;
• Insulation;
• Type of lighting;
• Double glazing;
• Draught proofing;
• Solar panels.

Minimum Energy Efficiency Standard (MEES)
The minimum energy efficiency standard (MEES) was introduced in March 2015 by the Energy Efficiency (Private Rented Property) (England and Wales) Regulations 2015.
Landlords must not continue to let any buildings which have an EPC rating of less than ‘E’ unless the landlord registers an exemption.

What are the exemptions?
Landlords can let a building to which the MEES Regulations apply but which is below the minimum standard if any of the exemptions apply. These are:

• The ‘Golden Rule’: where an independent assessor determines that all relevant energy efficiency improvements have been made to the property or that improvements that could be made but have not been made would not pay for themselves through energy savings within seven years. There are numerous examples of “relevant” energy efficiency improvements which include double-glazing and pipework insulation which need to be considered; wall-insulation measures are not required where an expert determines that these would damage the fabric of the property.

• Devaluation: where an independent surveyor determines that the relevant energy efficiency improvements that could be made to the property are likely to reduce the market value of the property by more than 5%.

• Third Party Consent: where consent from persons such as a tenant, a superior landlord or planning authorities has been refused or has been given with conditions with which the landlord cannot reasonably comply.

Exemptions must be registered on the central government PRS Exemptions Register. The exemptions are valid for five years only and cannot be transferred to a new landlord.

See Government advice here.

Possible new MEES rules

Note that Governemnt are debating on amending this rating so that it has to be a minimum of an ‘C’ rating.  But this is still not confirmed, and might be a minimum of ‘D’.   Whichever it is, landlords need to improve the energy efficiency of their properties, where they can.