I’ve written previously about my Ground Source Heat Pump (GSHP) and how it would be eligible for the Renewable Heating Incentive (RHI) once launched. Well, after several delays, the RHI was finally launched in early 2014 so I proceeded with making an application.

In case you are not aware of the RHI, it’s a UK Government backed subsidy scheme designed to encourage the up-take of renewable energy sourced systems for heating. This includes technologies such as ground and air source heat pumps, biomass boilers and solar thermal panels. The RHI scheme is similar to the Feed in Tariff (FiT) scheme already in place for solar PV installations in that you receive a tax free, index linked payment every quarter for a period of 7 years (compared with the 25 year period for solar PV FiT) based on the amount of renewable heat you are generating for yourself. When combined with the solar PV FiT payment, this more than covers the cost of installation of the new technology and also will pay for our only fuel source – electricity – for the next few years. For more information about RHI visit the Ofgem site.

Applying for RHI

While the actual RHI application process was relatively straightforward, getting to a point where I could make the application proved to be a bit more complicated…

One pre-requisite for applying for RHI is that you have had a Green Deal assessment carried out to determine the EPC rating for your property i.e. how energy efficient it is and what measures should be considered to improve it’s rating. I had already increased the loft insulation to a depth of 300mm in our relatively small loft space, and with the recent barn conversion utilising modern building techniques and materials our energy efficiency was better than it had been over previous years. As a result, our EPC rating came out as C (70) with an estimated total heating and hot water demand of 25,000kWh per year which wasn’t too bad considering it’s an early 19th century barn conversion.

Heat pump SPF assessment

However, the biggest delay to being able to make the RHI application was down to the desire to have a heat pump performance assessment carried out in an attempt to secure the highest possible RHI benefit rate. The RHI tariff is based on the amount of renewable heat generated, so this has to take into account the efficiency of the heat pump i.e. the more efficient the heat pump is, the greater the ratio of heat generated to electricity used to generate it (to drive the pumps). This efficiency is called the Seasonal Performance Factor (SPF) and the RHI scheme assumes an SPF of 2.5 for all applications for legacy heat pump installations. Now I was pretty sure my heat pump was more efficient than that so I commissioned Ice Energy, the supplier of the heat pump, to carry out a full assessment.

The assessment involved a site visit and survey with lots of measurements of rooms and construction materials taken followed by an office based analysis running the numbers through a spreadsheet. This process took longer than I had hoped and when I finally got the results back, I found that it had been assessed with an SPF of 2.5 – the same as the default! The reason for this was that two radiators in two large open plan connected rooms in the older part of the house were deemed as undersized. So, if I wanted to achieve an SPF of 2.8 I would either have to install additional radiators or replace the existing double panel double convector radiators with larger ones. As space was tight I decided to upgrade these radiators to triple panel triple convector equivalents, a job which I did myself.

Once the new radiators had been installed, Ice Energy issued an updated SPF rating of 2.8 which would increase the annual RHI benefit by around £300 – more than paying for the cost of the heat pump assessment and new radiator installation. With the final agreed SPF rating and Green Deal assessment / EPC I could then make the actual RHI application.

The application took a few days to go through an approval process, but once completed I was informed that my first quarterly payment of £733 would be made in November 2014, with subsequent index-linked payments being made quarterly for the full 7 years. I love my Ground Source Heat Pump!