Key terms explained for the Domestic Renewable Heat Incentive

These key terms have been designed as a reference tool when you need more detail on a specific topic.

You can also download this as a pdf: Domestic RHI reference document

Eligible purpose

There are restrictions on what the heat which an accredited plant produces can be used for. It must be used for an ‘eligible purpose’. This mean, heat for a domestic property must be generated by:

This heat must be generated by a Domestic RHI accredited renewable heating system, and must provide to a single Domesticopen key term pop-up property. To understand the full picture of technical eligibility requirements and purposes, please see the Reference Document.

Please note: Your heat pump or biomass system may also generate heat that is ‘non eligible’, however you’ll only receive payment for eligible heat produced.


To be eligible, among other requirements, a heating system must only provide heat to a single property which has a domestic Energy Performance Certificate (EPC) More.


To be eligible, among other requirements, a heating system must only provide heat to a single property which has a domestic Energy Performance Certificate (EPC) More.


To be eligible, among other requirements, a heating system must only provide heat to a single property which has a domestic Energy Performance Certificate (EPC) More.

Emission Certificate (RHI)

Below is a full list of the information that should be found on an RHI Emission Certificate. This information is used to indicate the amount of pollutants likely to be emitted by a biomass product when burning specific fuel types.

  • The name and address of the testing laboratory
  • The name and signature of the person authorised by the testing laboratory to issue the certificate
  • The issue date of the certificate and the certificate reference number
  • The date of the laboratory’s accreditation to EN ISO/IEC 17025:2005 and their accreditation number
  • The name, model, manufacturer and installation capacity of the plant
  • The testing date
  • Confirmation that oxides of nitrogen (NOx) and particulate matter (PM) have been tested on the same occasion and in accordance with the relevant EN standards, and, that the test was carried out at no less than 85% of the installation capacity of the plant. The requirements for testing of PM and NOx are:
  1. that testing is carried out in accordance with the provisions relevant to emissions of PM and NOx specified in whichever of the following standards applies: EN 303-5:1999; or, EN 303-5:2012
  2. that testing is carried out in accordance with EN 14792:2005 for NOx and EN 13284-1: 2002 or BS ISO 9096: 2003 for PM.
  3. that the emissions of PM represent the average of at least three measurements of PM emissions, and for at least 30 minutes duration.
  4. that the value for NOx emissions is derived from the average of measurements made throughout the PM testing process.
  • Confirmation that emissions of PM did not exceed 30 grams of PM per gigajoule net heat input (the rate of heat which is supplied to the plant by the fuel used, and based on the net calorific value of that fuel), and NOx did not exceed 150 grams per gigajoule net heat input.
  • The actual emissions of PM and NOx measured when the plant was tested.
  • A list of the types of fuel used during the testing and the types of fuel which can be used so as not to exceed the emission limits.
  • The moisture content of the fuel used during testing and the maximum moisture content which can be used so as not to exceed the emission limits.
  • A statement indicating whether the plant was a manually stoked natural draught plant.
  • A list of any other plants in the type-testing range of plants for the certificate, if any.

If the RHI emission certificate template submitted with the application does not contain the right information, for example, if there is information missing, or the levels of PM and/or NOx are not within the limits laid out above, it will not be considered a valid RHI emission certificate. 
The English language versions of the BS or EN standards referenced above can be found on the British Standards Institute (IBSN) website.


EN Standards for Technology Types

EN (European) standards for technology types are documents which set out the material requirements for each of the technologies, and which have been ratified by a European Standardisation Organisation.

All heating systems must meet the relevant EN standards in order to be eligible for the Domestic RHI scheme, however, meeting all of the standards does not automatically guarantee eligibility – the heating system would also need to meet the other scheme eligibility criteria relating to heating systems (Biomass products commissioned after 09/04/14 must also meet emissions standards see emissions certificate (RHI)).

The English language versions of these standards can be found on the British Standards Institute (IBSN) website. 

The EN standards that products have to meet for the Domestic RHI are:

Biomass Boilers: EN 303-5:2012, EN 12809:2001+A1:2004 or EN 303-5:1999.

Biomass Stoves: EN 14785:2006.

Heat Pumps: 
(a)    EN 14511-1: 2013, EN 14511-2: 2013, EN 14511-3:2013 and EN 14511-4: 2013;
(b)    EN 14511-1: 2011, EN 14511-2: 2011, EN 14511-3: 2011 and EN 14511-4: 2011;
(c)    EN 14511-1: 2007, EN 14511-2: 2007, EN 14511-3: 2007 and EN 14511-4: 2007; or
(d)    EN 14511-1: 2004, EN 14511-2: 2004, EN 14511-3: 2004 and EN 14511-4: 2004.

Solar Thermal: 
(a)    EN 12975-1:2006+A1:2010 and EN 12975-2:2006; 
(b)    EN 12975-1:2006+A1:2010 and EN ISO 9806:2013 or
(c)    EN 12976-1:2006 and EN 12976-2:2006.

Energy Performance Certificate (EPC)

An Energy Performance Certificate (EPC) is a report that assesses the energy efficiency of a property and recommends specific ways in which the efficiency of your property could be improved.

If you do not have a copy of an EPC for your property, you may be able to access a copy online, if one already exists. If you are in England or Wales, you can enter your postcode into the Landmark register. To check whether an EPC already exists for a property in Scotland see the Scottish EPC Register.

An EPC reference number is required as part of the application process for the Domestic RHI. The EPC is used to:

  • determine whether the property can be considered domestic
  • evidence that the required loft and cavity wall insulation measures have been installed.
  • determine the heat demand figure used for the payments calculation for non-metered biomass and heat pump applicants.

The heat demand figure is only included in EPCs for dwellings. A non-domestic EPC would not show this figure and therefore could not be used to work out payments using the deeming methodology.

Your EPC must include a heat demand figure and must be less than 24 months old at the date of application. Your EPC needs to accurately reflect information about your house, so if you have undertaken construction work on your property you may need to get a new EPC to ensure it reflects your circumstances.

If your EPC states that either loft or cavity wall insulation are required you must get an assessor to produce a second EPC after installing the insulation to prove that you have done this. Often your EPC assessor will be able to provide this service, however a list of Domestic Energy assessors is available at Find an energy assessor.