Assumptions

Tariff prices used

Oil =65 pence per litre

Boiler Efficiency 90%

Electricity = 13 pence per kWh

Property has average insulation, therefore  55 W/m²

Domestic RHI tariff prices (source DECC Domestic Renewable Heat Incentive, published 12^th July 2013)

Ground Source Heat Pump = 18.8 pence per kWh (Renewable heat) Now increased from 1st April 2015 = 19.10 p/kWh 

Air Source Heat Pump = 7.3 pence per kWh (Renewable heat) Now increased from 1st April 2015 = 7.42 p/kWh

Biomass = 12.2 pence per kWh Now decreased from 1st April 2015 = 8.93 p/kWh

For update regarding the domestic RHI tariff rates please see link below.

 

https://www.ofgem.gov.uk/environmental-programmes/domestic-renewable-heat-incentive/about-domestic-rhi/tariffs-and-payments-domestic-renewable-heat-incentive

For calculating renewable heat eligible for heat pumps the following formulae has been used

Eligible heat demand = Total heat demand x (1 - 1/SPF)

SPF = Seasonal Performance Factor

Note: The Domestic RHI has a duration of 7 years.