Electricity is required to run heat pumps and to avoid being rewarded for using this electricity, the RHI tariff payable is adjusted for the Seasonal Performance Factor (SPF) of the particular heat pump you have installed.
The SPF is calculated the following way:
This is to say, a heat pump with an SPF of 3 will on average deliver 3.0kWh of heat for every 1kWh of electricity it uses.
The adjusted annual RHI tariff payable is calculated as follows:
If the annual heat demand from your EPC is 15,000 kWh as in the example above this equates to an annual tariff of £1,071.00 not £1,606.50 as shown above, before the adjustment for your air source heat pump’s SPF.