The Domestic RHI scheme is primarily designed to support the retrofit of renewable heating systems. It is designed to help you make the switch from an existing fossil fuel or electric heating system to a renewable one.

Although the scheme was designed for the retrofit of renewable heating systems there is a special category of new-build properties that are eligible to apply to the scheme.  These are technically known as ‘eligible new-builds’ but we generally refer to them as custom-builds.

If your renewable heating system was installed during the construction of your property (e.g. so that it is the first heating system in a new property), and was not custom-built it won’t be eligible for the scheme. This applies if your heating system was commissioned (you can check your MCS certificate to see your renewable heating systems commissioning date) before your property was first occupied.

The rules around this are set out below.


A property is custom-built where an individual funds the construction and either commissions a builder or architect to create a ‘custom-built’ property for them or builds it themselves as a DIY ‘self-build’ project.

Newly built properties built by non-individuals won’t be eligible for the Domestic RHI – for example this applies where a commercial developer or a social landlord has built the property using company funds, even if the properties are later sold to individuals.

In order for a custom-build property to be eligible, it will need to meet the following criteria:

  1. The property must have been built principally using the labour or resources of the first owner. This means that the first owner of the property must have either physically constructed it or financed its construction. Where the first owner financed the construction of the property, this can be through the use of a custom-build mortgage or loan.
  2. The first owner and all subsequent owners of the property must be individuals. The property cannot have been owned, wholly or partly, and at any stage, by a person who is not an individual. Companies or organisations that have constructed new properties and installed a renewable heating system as part of this construction will not be considered custom-builders. If you buy an “off-plan” property from a developer, it is unlikely to be eligible, even if you input substantially into the design, including instructing the developer to install renewable heating.

If you apply for a renewable heating system that was installed in your property before it was first occupied, you may need to provide us with evidence showing that your property is a custom-build:

  • If we ask you to provide evidence we will require documentation confirming you or the first owner funded the build of the property (for example an invoice for substantial structural materials or work).
  • We may also require evidence that the property has not been owned by a company or organisation (for example the title deeds for the property)

Is my property a custom-build or a retrofit?

Please note the custom-build rules only apply where your renewable heating system was installed before your property was first occupied.

Replacement heating systems commissioned after your property was first occupied do not count as custom-builds:

  • If you custom-built your own home several years ago and are only now replacing your old boiler with a renewable heating system, this would be a replacement.
  • If you have bought a fairly new property in which a fossil fuel or electric heating system was included during the construction of the property, and you replace this heating system with an eligible renewable technology after the property was first occupied, then this is a replacement.

Conversions and renovations

Renovations: If you renovated your domestic property significantly (e.g. you stripped the building down to a shell and re-built, or extended the property), it will have been occupied, at some point, before the renewable heating system was commissioned. You will not be able to meet the custom-build criteria and will need to follow the normal ‘retrofit’ application route.

Conversions: If your property was converted from a building used for non-residential purposes (e.g. a barn or warehouse) into a dwelling, it will not have been occupied (as a ‘dwelling’) while it was used for non-residential purposes. If your converted property was not occupied before the renewable heating system was installed, you will need to meet the custom-build eligibility criteria.