Minimum Energy Ratings from 2018 (MEES)
Since April 2018, private domestic and non-domestic landlords need to ensure that their properties reach at least an E Energy Performance Certificate (EPC) rating, or have installed those improvements that could be funded using available finance or subsidies available to pay for them, before granting a tenancy to new or existing tenants".
At the moment domestic landlords are not expected to provide up front finance, but to gain an exemption from the requirement they will have to show that funding is not available, this may require an application to the Green Deal Finance company. From April 2019 domestic landlords will be required to spend up to £3,500 (inc vat) per property before applying for an exemption from the minimum energy requirement.
If full funding is available through GDFC or ECO or similar and;
a, the measures are not adversly affecting a historic property, or
b, a surveyor has not recommended the measures are not applied,
then they will have to be carried out. It is up to the landlord then how to finance them, they could then use a Green Deal loan (whereby the tenant repays the loan, though these are very rare) raise the money elsewhere or use their own funds.
Non domestic landlords will have to bear some up front costs if the measures show a reasonable pay back period.
Government guidance to the regulations and how they apply to both domestic and non domestic properties can be found here
https://www.gov.uk/government/publications/the-private-rented-property-minimum-standard-landlord-guidance-documents
and for an update on the change in the requirement for domestic landlords see https://www.elmhurstenergy.co.uk/government-announces-planned-changes-to-mees-prs-regulations
These requirements will then apply to most private rented properties, including occupied properties - from April 2020 in the domestic sector and from April 2023 in the non-domestic sector.
Dave Green Energy Services have set up a MEES service and they are working with the National Trust and Central England Co-op plus smaller landlords.