From 1 April 2018, any new tenancy, renewal or extension, in order to be rented, the building must have a minimum energy rating of “E”. The rating is found on the Energy performance Certificate for the building.
From 1 April 2020, the minimum level “E” applies to all tenancies – including existing.
As a side note, non-domestic properties are required to have a minimum “E” rating from 1 April 2018 for all new tenancies, rentals and extensions. From 1 April 2023, all non-domestic lettings (including existing) must be at an “E” rating