When launched in UK in 2011, the renewable heat incentive scheme (more commonly known as the RHI) was the first such incentive scheme in the world.

Although it has been the subject of plenty of criticism over the years, the RHI has unarguably served to boost the renewable heating industry in the UK, throwing focus on new forms of low carbon heating technology from heat pumps to biomass boilers.

The UK government certainly believes it has served to kick-start development of low-carbon heating, assisting the transition away from conventional heating for a wide range of customers, with the two schemes: Domestic and Non-Domestic, drawing in homeowners, commercial building operators and public bodies, including charities.

‘The RHI is designed to bridge the gap between the cost of installing renewable technology and that of conventional heating systems such as gas boilers.’

The heart of the scheme is a payment per kWh of renewable heating used (the so-called ‘tariff’, with the tariff varying from technology to technology, based on the carbon efficiency.

To receive support through the Domestic RHI, households must install an eligible technology - biomass boilers and stoves, air source and ground source heat pumps or solar thermal systems - to heat their home. They can then apply for financial support to help cover the cost of their systems. The technologies must be fitted by a qualified installer, certified by the Microgeneration Certification Scheme (MCS), ensuring the technologies meet certain standards and is installed properly.

For the Non-Domestic RHI, the larger installations enable the specification of a wider range of renewable technologies. These currently include: biomass and biogas boilers; heat pumps; solar thermal and deep-geothermal systems; and CHP (combined heat and power) systems using renewable fuels or sources.

In each scheme the tariffs are paid against heat used, measured usually by heat meter, or for domestic properties based on the home’s Energy Performance Certificate. The domestic scheme pays owners for seven years, whereas for the non-domestic it is 20 years, reflecting the bigger installations.

‘In November 2016, the government announced a review of the schemes to reflect the continuing development of the various technologies'.

‘The new version of the scheme has seen increased incentives for air source heat pumps - a 25% increase in the payments made - which the government says is in recognition of the likely importance they will have in the long term decarbonising of heat, particularly where properties are not connected to the gas grid. The tariff increase is clearly intended to drive increased take-up of the air source technology.’

The scheme also recognises the importance of having the air source heat pump running at its optimum efficiency, so there is now a requirement for domestic installations to have a smart meter fitted for homeowners to use.

The new Domestic scheme also sees increased payment for biomass boilers and retains payment for use of solar thermal systems, which can be installed alone or in combination with other renewables such as heat pumps.

There is some debate as to whether offering RHI payments really changes the decision of specifiers– some in the industry believe that the payback times for renewable technology are still too long, even with RHI payment added in, and that what is required to really change behaviour is legislation requiring lower carbon heating.

‘What is clear is that the Renewable Heat Incentive has provided a much needed spur to the development of the relatively young technologies involved and that the likes of heat pumps and biomass boilers are now set to be an integral part of the UK’s moves towards decarbonising heating.’