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Can you tell your RHI from your elbow?


So, you need a new boiler. It is a choice between £2-4k to replace the gas one or £4-8k for the much greener air source heat pump that you know will be your only option in 10 years time, but which looks too expensive now. Well – with RHI it is typically cheaper…  

What is RHI?  

RHI stands for 'Renewable Heat Incentive' and that is exactly what it is, an incentive to get people to use renewable heat now, rather than wait until it all becomes cheaper. It is a payment, paid quarterly or annually for a period of 7 years and it can be quite significant.  

How Do You Calculate It?  

Firstly, you must have an EPC that is no more than 2 years old. If you don't have one, check our recommended suppliers (under EPC's) – it does not take long to get one, and you must have one whenever you let your property anyway.

If you can't find your EPC, just look it up on the register (Find an energy certificate – Find an energy certificate – GOV.UK (, just enter the postcode of your property and select your property from the list. If you look at the report, after the rating and its explanation is a section headed 'Environmental Impact of this Property' and after that, 'Estimated Energy Use and Potential Savings', within that section, look for the following information (info here is for a specific, but completely normal, 3-bed Portsmouth terrace house just for example):

Heating use in this property

Heating a property usually makes up the majority of energy costs.

Estimated energy used to heat this property

Space heating

17454 kWh per year

Water heating

2235 kWh per year

Potential energy savings by installing insulation

Type of insulation

Amount of energy saved

Loft insulation

3908 kWh per year

Cavity wall insulation

3272 kWh per year

Once you have found this information, you need to go to an RHI calculator like this one: BEIS Domestic RHI Calculator (

The calculator will ask for some of the above information from the EPC as below:

Your home's heat demand

Existing Dwelling 

Impact of loft insulation

  Impact of cavity wall insulation  

Impact of solid wall insulation

Space heating (kWh per year)





Water heating (kWh per year)


You can then choose what form of renewable heat you are considering (solar thermal, biomass, air source or ground source heat pump) and the calculator will tell you how much you will be paid. So in the example of the 3 bed terrace in Southsea used here,installing the £4-8k air source heat pump would generate payments of £205 per quarter / £5,740 over 7 years whereas 'ground source' would generate £11,900 over 7 years – so even the higher install cost of that solution suddenly becomes appealing, even before you realise that your heating bills will be lower as well…. 

 How Do You Apply For RHI?    

You simply need to get an MCS (Micro generation Certified System installer) to install said solution and then go online within 2 years to claim your payments. Full details here: Domestic Renewable Heat Incentive (RHI) | Ofgem

That expensive 'green solution' does not sound so expensive anymore does it? Want to know more? Come to our June member meeting and speak to our panel of 'green' experts.

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